Introduction
Our project is a digital stethoscope that displays your heartbeat on any television. It also calculates beats per minute and alerts you if your rate falls out of a specified range.
At the highest level, the design of our project centers around an acquisition circuit, data processing in two MCUs, and the output on a TV screen. The first part of the stethoscope is the acquisition unit, which consists of an actual stethoscope mated with a microphone, and an amplifier circuit. The microphone captures the audible signal from the body that is acoustically amplified by the stethoscope. After that, we bias and set the gain of the signal using an operational amplifier so that the ADC on the MCU will be able to pick up the signal. The analog data will be independently sampled by the two MCUs at a rate appropriate for display on the TV (CPU1) and a rate sufficient to capture the appropriate characteristics of the signal for beat detection (CPU2). CPU2, uses a moving threshold scheme to detect the actual heartbeats, and from that derive the heart rate. Then the signal is blasted to the TV, which also displays pertinent data, such as beats per minute. Additional information is displayed on the HyperTerm. If applicable, a buzzer will sound if your heart rate falls out of a specified range.
High Level Design
The Idea and Requisite Knowledge
The idea for our project is pretty much our own, and is really just a proof of concept and a good demonstration of the capabilities of the Mega32. There are many instruments commercially available to measure your heart rate, even with far greater accuracy than we obtain. We thought it would be interesting to implement a usable piece of equipment that puts the heart rate on the TV and gets the correct beats per minute (BPM) reasonably well.
There is no requisite knowledge to understand our project beyond the content of ECE 476, except maybe that of low-pass filters. Our acquisition circuit contains an analog low-pass filter and the second MCU which calculates the actual BPM uses a digital low-pass filter also. The characteristics for the analog filter and the math for the digital filter appear in the program/hardware design section, where they can be viewed in context. It is also good to know that there is a major spike for each heartbeat.
General Design
In our final project we implemented a digital stethoscope. At the highest level, the design of our project centers around an acquisition circuit, data processing in two MCUs, and the output on a TV screen. The stethoscope detects and displays the heart beat and BPM. The first part of the stethoscope is the acquisition unit, which basically consists of an actual stethoscope mated with a microphone, and an amplifier circuit. The microphone captures the audible signal from the body that is acoustically amplified by the stethoscope. After that, we set the gain of the signal using an operational amplifier so that the ADC on the MCU will be able to pick up the signal. This is necessary because the amount of signal you get from the heartbeat in your neck is probably much more than the heartbeat in your wrist, for example.
The analog data will be independently sampled by the two MCUs at a rate appropriate for display on the TV (CPU1) and a rate sufficient to capture the appropriate characteristics of the signal for beat detection
(CPU2). With uniform data to work with in CPU2, we then wrote a scheme to detect the actual heartbeat, and from that derive the heart rate. There are many methods we could use to implement this including absolute minima/maxima, average min/max, and Fourier (frequency) representation of the signal. Our basic approach uses a moving threshold approach that is outlined in detail in the software section below. The heartbeat signal and rate (beats per minute) will then be output to the TV screen, similar to ECE476 lab 4. Figure 1 shows the basic setup of the entire project.
Figure 1
Hardware/Software Tradeoffs
One example of a hardware/software tradeoff in our project was our decision to eliminate automatic gain control. We included this feature in our proposal because it would improve the robustness of the digital stethoscope by increasing the number of areas on your body that you could take a reading. (ie. The signal from your neck is different from your wrist.) Basically, when we deemed hardware AGC too difficult, we decided to implement it in software. However, it turned out that we really didn’t need it at all, since the output from the acquisition circuit on the neck was relatively stable and consistent, even with different users. We could have just blown the output of the microphone up in software, but we decided to use an op-amp to obtain resolution on the analog to digital conversion. Also, the beats from weaker points on the body, like the wrist, just did not come out looking like beats at all.
Another tradeoff was the way that we implemented the mute function for the alert buzzer. Instead of having a few logic gates hanging off of the high and low violation control lines between the two CPUs, we decided to implement the logic inside the second MCU and just have an extra output for the buzzer. This saved extra external hardware, but added a level of complexity to the code. In general, we tried to implement as much as possible in software, when appropriate.
Another limiting factor of the Mega32 CPUs is that they have a finite number of I/O ports. Since we have 2 CPUs (one for displaying information, one for computing information), there is a limit on the amount of information that we could output, on the TV especially. Because we essentially had more numbers to put on the TV than we had I/O ports to send it between the CPUs, we decided to implement the RS232 interface to HyperTerminal on the PC. A picture of the output on the HyperTerminal can be found in the appendix.
Recognized Standards
The first standard in use for our project is the same we used in ECE476 lab 4, the RS170 composite video standard and the NTSC frame rate. Our TV signal is non-interlaced, black and white video just as in lab 4. The RS170 standard dictates the 3 voltages for black, white and sync, as well as the 4:3 aspect ratio, and the widths of the horizontal and vertical sync pulses and their front and back porches. Additionally, the RS170 standard dictates that there are 525 lines per frame, and 60 frames per second. As described above, our implementation uses a 30fps, non-interlaced version.
The second standard that we used was RS232 serial interface with the PC. RS232 is a common serial interface for digital data communications. It specifies signal voltages, timing, and protocols for information exchange and mechanical connectors. Because our RS232 was implemented on the STK500, we did not have to touch any of the specifics of the protocol as the Mega32 implements it for us.
Patents and Intellectual Property
There are already many methods of detecting heart beat patterns and pulse rates. Undoubtedly many of these methods are protected under patent law, but the simplicity of our design will not encroach on any of those complex designs. There are many patents on stethoscopes. While we are using one, however, we are not designing it. This will probably limit the chances of our device receiving a patent. Really, the only patent potential our device has is the fact that it plugs into your own TV.
We also feel that credit is due to others for part of the code used in our CPUs. This will also limit our patent potential. Professor Bruce Land of Cornell University supplied the basic code for NTSC video output on the Mega32 in the ECE476 lab 4. We use an altered version of this code in CPU1 which outputs the heartbeat signal to the TV. Also, the majority of the button debouncing state machine in CPU2 was also supplied by Dr. Land in the ECE476 lectures. A general diagram of the state machine can be found in the Appendix.
Program/Hardware Design
Hardware Details
The first part of our circuit was the stethoscope itself. Aaron’s father is a cardiologist and we were able to obtain a used stethoscope from him free of charge. Originally the stethoscope had very flexible medical latex tubing which mated the end piece with the metal frame and the earpieces. The problem with the tubing is that we could not find a microphone small enough to fit inside it. Our solution was to make a trip to the hardware store and pick up some vinyl tubing. We used 3/16” inside diameter tubing for the main length and then 2 fitted larger sizes to telescope up to the size of our microphone. After we worked the microphone down into the largest piece, we secured it with a metal hose clamp, as shown in figure 2. We initially figured that the tube needed to be sealed so that acoustic loss would be minimized. We attempted to melt the pieces of tubing together, but that was quite disastrous and we ended up burning holes in the tubing. We eventually decided (after reassurance from Professor Land
Figure 2
The WM-034DHB microphone we used is omnidirectional with -42dB sensitivity, >60dB SNR, and a 20-16kHz response range. This particular microphone requires a 1.5V bias to operate properly. We built a bias circuit using a 10kΩ trimpot, a 2N3904 NPN transistor, and a few resistors. The diagram for the microphone bias circuit is shown in figure 3. The gain portion of our circuit consists of an LMC7111 op-amp set up with a gain of 7, in a low-pass configuration, as shown in figure 4. For this circuit, the equations for the low-pass time constant and amplifier gain are as follows:
We used an actual time constant of 0.5 and a gain of 7, as shown in figure 4. The input of the amplifier was coupled to a DC voltage of around 2.5V. This was necessary to center the amplified signal in the A/D range for the MCU. We implemented this with a voltage divider with 2 x 1MΩ resistors, as shown in figure 4.
Figure 3 Figure 4
Since we use two MCUs (as detailed in the software details section), we had to build one MCU setup on a white board. Figure 5 is a photograph of CPU1 and the TV output circuit on the white board (The MCU and TV circuit are on the lower of the two whiteboards shown; the upper is the microphone bias and amplifier circuit, along with the buzzer). The TV uses pin D.5 as the sync signal, and D.6 as the video input. HyperTerm was set up by connections from the STK500 to the PC, D.0 was the receive bit and D.1 was the transmit bit. Please refer to the appendix for a picture of the actual Hyperterm output. The TV output DAC, shown in figure 1, was provided to us in ECE 476 lab 4. The appendix contains a detailed diagram of how the Mega32 is implemented on the whiteboard.
Figure 5
The final piece of hardware we used was a CT-1205C buzzer, which is shown on the upper board in figure 5. This is used to indicate a violation of the high or low BPM violations. We bought this particular buzzer because it was loud, annoying, inexpensive, and could be driven off of a single output pin in terms of current and voltage.
Software Details
Initially we planned on using only one MCU, but we quickly realized that it just was not possible to do all the necessary calculations and blast output to the screen on one MCU. The 2-CPU solution we came up with uses CPU1 for the TV output, and CPU2 as a processing unit. Both CPUs sample the same heart beat signal independently of each other and at different rates.
Our CPU1 code was a modified version of our ECE476 lab 4 code, which in turn was a modified version of Professor Land
CPU1 also takes several control lines that are generated by CPU2, including high and low violation lines, run/stop and one/two second screen widths from the buttons attached to CPU2. Finally, there are 8 parallel bits which transmit the beats per minute as they are calculated. Figure 1 shows how the two CPUs fit together and interface, along with outside connections. The following table (figure 6) outlines the various definitions for the interface and control lines.
Figure 6
CPU2 has three basic tasks. First, it is responsible for debouncing the 7 buttons attached on port B. We used a state machine structure that was similar to the one presented in ECE 476 lecture for debouncing buttons. The button functions are outlined in the following table, and a general diagram for a debouncing state machine can be found in the Appendix.
Figure 7
Second, CPU2 is responsible for calculating the BPM of the sampled signal. We chose to go with a windowed sampling scheme, instead of a real-time approach. This basically means we take a string of samples over a certain time period, process the data, determine the BPM, and start the next sample string. In order to cover the reasonable BPM ranges of the human cardiovascular system, we were aiming for reliable performance between 60 and 180BPM. The low end is where we really had to worry since at 60BPM, there is one beat each second.
Our detection scheme basically attempts to find pulse peaks in the data, determines the time between the peaks, and then converts that to BPM. The sample window had to be long enough to get at least two beats in one window for the lowest range. At 60BPM, a 2 second window gives this, and this is the window we chose. The downside to the long sample window is that we can only provide a new BPM update every 2 seconds. This decision between sample window length and the rate at with the BPM is output is a tradeoff that we made. Heart rates lower than 60BPM can be detected if two pulses happen to fall inside the 2 second window, but since the phase of the beats is relatively random, there is no guarantee this will happen. We modified our code such that if we only identified one peak, we would leave BPM unchanged. If we didn’t identify any peaks, then BPM was set to 0. In the lab, we were able to reliably detect heart rates of around 50BPM. The high end accuracy was limited by how much time we waited after identifying the first peak before looking for the second peak. Our code waits 150 samples at 2ms each, or a total of 300ms, which equates to a maximum of 200BPM.
The beat detection algorithm is actually quite simple. We took 1000 data points over 2 seconds, giving a sampling rate of 2ms. This corresponds to a sampling frequency of 500Hz. The Nyquist Sampling Theorem states then that the largest frequency component present in our sampled signal is 250Hz. This in effect is a low pass filter. This is not a problem, however, since we are only interested in the low frequencies anyway. A second digital low-pass filter was implemented as a weighted rolling average. The filter looks like this:
The alpha value in the equation dictates the amount of “smudging” that occurs. This in effect smoothes the data and lowers the noise floor. We experimentally determined the best alpha was 0.8. The resulting 1000 data points in CPU2 then would look something like figure 8, which graphs actual data we collected by printing it to theHyperTerm. Before sampling and the digital low-pass filter, the SNR of the heartbeat signal was about 5, but you can see from figure 8 that the post-filtered SNR is much higher. The detection uses a moving threshold algorithm. The first step is to determine the maximum value of data in the sequence. Then, we look for successive peaks with increasing slopes within 80% of the maximum value. This inherently assumes that the peaks in the input sequence are relatively stable, and within a reasonable range above the secondary peaks and noise.
Figure 8
The third function of CPU2 is to send data to CPU1 and to control the alarm buzzer. CPU2 sends BPM through PORTC and information about the modes of operation and violations through PORTA to CPU1. CPU2 sends one bit to the buzzer for violations through PORTA. Figure 1 shows the specific connections and figure 6 outlines the control lines. In addition to the data sent to CPU1, the second CPU also outputs other (excess) data to the HyperTerm. This includes the maximum value (out of 255) received over the last sample window, the indexes of the two beats used to determine the BPM, the actual BPM, and the high and low threshold values which are settable by the buttons attached to PORTB. The data is updated every 2 seconds, just like the BPM value. Typical HyperTerminal output is shown in the Appendix.
Things We Tried That Didn’t Work
Our project was very successful as a whole, but there were a few things that did not work out as we had originally planned. First, we planned to display the high/low violation values on the TV. The problem with this is that the buttons to set the high/low values are attached to CPU2 on the STK500. We did not have enough output ports left to send two 8bit numbers to CPU1. Because there was no easy way to synchronize the CPUs we settled on using HyperTerm to display the high/low violation values. We did, however, print “HIGH” or “LOW” on the screen if the respective violations occurred.
Second, we wanted to blast the digitally filtered heartbeat signal to the television. The filtering would have to be done on CPU1 since there is too much data to transfer it from CPU2 to CPU1. Since the trace on the TV “rolls” across the screen, a significant amount of logic had to be inserted to keep track of the “edge” of the data trace. The filter would need to start on the edge, wrap around the screen and continue back to the edge so that the data is filtered in order. When we implemented this, the code was just too bulky, and interfered with the timing of the TV output. We decided to settle for displaying the heartbeat signal that was amplified and filtered in an analog fashion on the television.
Lastly, we wanted to implement automatic gain control (AGC), but realized that it was not very useful or necessary. In addition, it is nice to see the relative strength of different heartbeat signals. This was explained in the above section, Hardware/Software Tradeoffs.
Results
Speed of Execution
In CPU1, our digital stethoscope draws the heartbeat trace to the television with a delay imperceptible to humans. Since CPU2 uses a sampling window to determine the BPM, there is an inherent 2 second delay between updates of the heart rate. The HyperTerm is updated every 2 seconds as well. All other components of our project execute with no perceptible delay and no concurrency issues ever arose.
Accuracy
Our design was able to achieve a good level of accuracy, considering the cheap parts used and simple structure of design. The signal to noise ratio for the amplified input (which was then sampled), was around 5:1, so the heartbeat displayed on the screen looks good. Figure 9 shows a typical trace on the TV screen. On occasion, some stray pixels were left on the screen, probably due to the timing of our CPU1 code. We were not able to entirely eliminate this, but it does not happen very often and we modified the code to solve this problem and make it happen as seldom as possible. When the digital stethoscope is put into stop mode and then started again these imperfections are cleared when the screen is initialized. On the whole, though, our trace is of very good quality, as is demonstrated below.
Figure 9
Accuracy for our BPM calculation was discussed in the software design section. In general, we found that our digital stethoscope was accurate in the range of around 50-180 BPM. We used a function generator to help determine these bounds. In addition, BPM is calculated every 2 second from the time between two successive peaks and then that time per beat is converted into BPM. Consequently, the actual BPM is only updated every 2 seconds.
Our digital stethoscope works most reliably with a strong heartbeat signal. If a signal is not very strong, it may be hard to detect peaks because of inherent noise. Thus, on a few occasions, we found it necessary to get out of our chairs in the lab and run up and down the stairs a few times to keep our blood moving. It’s quite amazing how much this makes a difference. Finding the right place for the end piece of stethoscope is also very important. The strongest and most reliable place on the body that we found was the neck. We had limited success on the heart when blood flow was good. The wrist rarely worked at all. Additionally, you must be very still and quiet to use our device. Talking or movement of the stethoscope produces output far above the voltage rail of the amplifier, and the resulting heartbeat trace and BPM will not be displayed accurately. This is however inherent to any stethoscope and not unique to our project; if an old-fashioned stethoscope moves around or the patient talks when it is on his/her neck there will be mostly noise.
Safety Enforcement and Interference
Our design is inherently safe for several reasons. First, the only contact our device has with the user is the end piece of the stethoscope; it is placed against his/her neck or chest. This is as safe as using a normal stethoscope. Additionally, we use no high voltages or currents in any of our circuits. Humans are protected from this anyway since the plastic tubing connecting the microphone and the stethoscope end piece are insulators and do not conduct any current.
Our chip to chip communication is purely wired, so our design does not interfere in any way with other groups’ designs.
Usability
Our digital stethoscope is easy to use. The most difficult part of using the digital stethoscope is to find the best place to measure your heartbeat. This is typically on your neck, but the chest as also well has worked in the lab. Additionally, people with heartbeats that are not very strong will have a harder time finding the right place and getting a good display of their heartbeat on the television. If you are having trouble getting a good display of your heartbeat, you can always run up and down the stairs or do something equivalent to raise your heart rate and blood flow. The increase in heart rate and stronger beats will make a better display.
Others ECE 476 students have had no problems working our project after a simple explanation; our design is user friendly.
Conclusions
Analysis of Results
We were very happy with the final results of our project. The finished product met our expectations and worked as well as we could have hoped. Our project demonstrates what can be done using Mega32 MCUs with some additional circuitry and components. The display of the heartbeat is very good and the BPM calculations are accurate for a wide range of heart rates. The proper placement of the end piece on the body—in order to get a good signal—can be finicky at times, but with some practice, you can find a good spot easily, and it will give excellent results.
If we had more time, there are some additions to the project that we would attempt. First, we would try to improve the low end BPM calculation accuracy, without delaying the BPM displayed on the television when unnecessary. We would try to go about this by altering when we stored ADC values in the array, so that the peak of the heartbeat would be near the beginning of the array and the beat would be properly detected. Second, we would try to make our digital stethoscope work from more points on the body. This would likely entail implementing additional amplification for certain parts of the body and possibly additional filters for different sources for noise. Third, we would try to output a smoother signal on the television, similar to the signal we used calculated BPM. It was not implemented in our project because it screwed up the timing, but we may be able to implement it, although it would be difficult, if we spent significant time and modified some of the structure of our CPU1 code.
Standards & Intellectual Property
As discussed above, much of the TV output code inside CPU1 was provided for us in the ECE476 lab 4 by Cornell Professor Bruce Land. Additionally, the debounce state machine for the buttons attached to CPU2 was derived from Professor Land
Ethical Considerations
In all stages of design, implementation and testing, we complied with the IEEE code of ethics. Five points from the IEEE code of ethics are referenced below, followed by an explanation of how we complied with them.
Point one: to accept responsibility in making engineering decisions consistent with the safety, health and welfare of the public, and to disclose promptly factors that might endanger the public or the environment
Our project is safe and users are not at risk when using our digital stethoscope. The digital stethoscope can alert the user through a buzzer if his/her heart rate falls outside of a safety zone that the user can define. Also, a trained professional may be able to identify problems with heartbeats by viewing the display from our project onto the television. Our project works to promote health and welfare of the public and does nothing to harm people.
Point three: to be honest and realistic in stating claims or estimates based on available data
From the beginning, we had a realistic view of the project in mind and set goals accordingly. We made every possible effort to obtain reliable data and report it in an objective fashion. We stand behind all claims in this report, as they are honest and reliable.
Point seven: to seek, accept, and offer honest criticism of technical work, to acknowledge and correct errors, and to credit properly the contributions of others
On this website, we have properly credited the contributions of others. At several points in the project, we asked Professor Land
Point nine: to avoid injuring others, their property, reputation, or employment by false or malicious action
No one was injured in any way during the completion of the project. We were respectful of other’s property, space, and need to use lab benches.
Point ten: to assist colleagues and co-workers in their professional development and to support them in following this code of ethics
During this project, our colleagues and co-workers were fellow ECE 476 students and our partners. We tried to be as helpful as possible when other groups asked us questions or showed us their projects. The project was completed earlier and the end result was better because we worked together as a group and had high standards for each other’s work. In addition to assisting in professional development, we also supported each other in following the IEEE code of ethics. For example, we made a conscious effort to both make sure we presented our project honestly and objectively and cited sources properly.
Appendix
Other figures and diagrams
Below is a general state machine diagram for a button debouncer. This is implemented in code for each of the buttons used. There are slight modifications to increment/toggle variables on a button push, and also to make sure the action does not happen more than once per push.
Below is a general diagram of how the Mega32 was implemented on the whiteboard. This diagram can be seen in the photo in figure 5.
The following are some additional pictures that we took of our project. They include Aaron demonstrating how to hold the stethoscope end piece to his neck, typical HyperTerminal output, and an overall view of our two whiteboards and the STK500.
Aaron doing a demonstration
Typical Hyperterm output
Overall Project View
References
Datasheet for the Atmel Mega32. Available: http://instruct1.cit.cornell.edu/courses/ee476/AtmelStuff/full32.pdf
Datasheet for the WM-034DBH microphone. Available: http://www.panasonic.com/industrial/components/pdf/em16_microphone%20schematic_dne.pdf
Code
CPU1
// EE 476 FINAL PROJECT CPU1 CODE
// Aaron Davis (amd43) and Brandon Richter (bcr5)
//************************************************************
#pragma regalloc- //I allocate the registers myself
#pragma optsize- //optimize for speed
//include necessary files
#include <Mega32.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <delay.h>
//cycles = 63.625 * 16 Note NTSC is 63.55
//but this line duration makes each frame exactly 1/60 sec
//which is nice for keeping a realtime clock
#define lineTime 1018
#define begin {
#define end }
// define top and bottom of screen
#define ScreenTop 30
#define ScreenBot 230
//NOTE that v1 to v8 and i must be in registers!
register char v1 @4;
register char v2 @5;
register char v3 @6;
register char v4 @7;
register char v5 @8;
register char v6 @9;
register char v7 @10;
register char v8 @11;
register int i @12;
#pragma regalloc+
char syncON, syncOFF;
int LineCount;
int time;
char bpm; //beats per minute from CPU2
// ADC
char time_offset, time_counter, time_index;
char values[128], values_old[128];
char run_state;
//loop vars
unsigned char j;
int sum;
char screen[1600], t, ts[10];
// strings we print to the screen
char cu1[]="DIGITAL";
char cu2[]="STETHOSCOPE";
char cu3[]="BPM";
char hl1[]="OK ";
char hl2[]="HIGH";
char hl3[]="LOW ";
char hl4[]="ERR ";
char sec[]=" SEC";
//Point plot lookup table
//One bit masks
flash char pos[8]={0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01};
//define some character bitmaps
//5x7 characters
flash char bitmap[38][7]={
//0
0b01110000,
0b10001000,
0b10011000,
0b10101000,
0b11001000,
0b10001000,
0b01110000,
//1
0b00100000,
0b01100000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
0b01110000,
//2
0b01110000,
0b10001000,
0b00001000,
0b00010000,
0b00100000,
0b01000000,
0b11111000,
//3
0b11111000,
0b00010000,
0b00100000,
0b00010000,
0b00001000,
0b10001000,
0b01110000,
//4
0b00010000,
0b00110000,
0b01010000,
0b10010000,
0b11111000,
0b00010000,
0b00010000,
//5
0b11111000,
0b10000000,
0b11110000,
0b00001000,
0b00001000,
0b10001000,
0b01110000,
//6
0b01000000,
0b10000000,
0b10000000,
0b11110000,
0b10001000,
0b10001000,
0b01110000,
//7
0b11111000,
0b00001000,
0b00010000,
0b00100000,
0b01000000,
0b10000000,
0b10000000,
//8
0b01110000,
0b10001000,
0b10001000,
0b01110000,
0b10001000,
0b10001000,
0b01110000,
//9
0b01110000,
0b10001000,
0b10001000,
0b01111000,
0b00001000,
0b00001000,
0b00010000,
//A
0b01110000,
0b10001000,
0b10001000,
0b10001000,
0b11111000,
0b10001000,
0b10001000,
//B
0b11110000,
0b10001000,
0b10001000,
0b11110000,
0b10001000,
0b10001000,
0b11110000,
//C
0b01110000,
0b10001000,
0b10000000,
0b10000000,
0b10000000,
0b10001000,
0b01110000,
//D
0b11110000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b11110000,
//E
0b11111000,
0b10000000,
0b10000000,
0b11111000,
0b10000000,
0b10000000,
0b11111000,
//F
0b11111000,
0b10000000,
0b10000000,
0b11111000,
0b10000000,
0b10000000,
0b10000000,
//G
0b01110000,
0b10001000,
0b10000000,
0b10011000,
0b10001000,
0b10001000,
0b01110000,
//H
0b10001000,
0b10001000,
0b10001000,
0b11111000,
0b10001000,
0b10001000,
0b10001000,
//I
0b01110000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
0b01110000,
//J
0b00111000,
0b00010000,
0b00010000,
0b00010000,
0b00010000,
0b10010000,
0b01100000,
//K
0b10001000,
0b10010000,
0b10100000,
0b11000000,
0b10100000,
0b10010000,
0b10001000,
//L
0b10000000,
0b10000000,
0b10000000,
0b10000000,
0b10000000,
0b10000000,
0b11111000,
//M
0b10001000,
0b11011000,
0b10101000,
0b10101000,
0b10001000,
0b10001000,
0b10001000,
//N
0b10001000,
0b10001000,
0b11001000,
0b10101000,
0b10011000,
0b10001000,
0b10001000,
//O
0b01110000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b01110000,
//P
0b11110000,
0b10001000,
0b10001000,
0b11110000,
0b10000000,
0b10000000,
0b10000000,
//Q
0b01110000,
0b10001000,
0b10001000,
0b10001000,
0b10101000,
0b10010000,
0b01101000,
//R
0b11110000,
0b10001000,
0b10001000,
0b11110000,
0b10100000,
0b10010000,
0b10001000,
//S
0b01111000,
0b10000000,
0b10000000,
0b01110000,
0b00001000,
0b00001000,
0b11110000,
//T
0b11111000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
0b00100000,
//U
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b01110000,
//V
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b01010000,
0b00100000,
//W
0b10001000,
0b10001000,
0b10001000,
0b10101000,
0b10101000,
0b10101000,
0b01010000,
//X
0b10001000,
0b10001000,
0b01010000,
0b00100000,
0b01010000,
0b10001000,
0b10001000,
//Y
0b10001000,
0b10001000,
0b10001000,
0b01010000,
0b00100000,
0b00100000,
0b00100000,
//Z
0b11111000,
0b00001000,
0b00010000,
0b00100000,
0b01000000,
0b10000000,
0b11111000,
//figure1
0b01110000,
0b00100000,
0b01110000,
0b10101000,
0b00100000,
0b01010000,
0b10001000,
//figure2
0b01110000,
0b10101000,
0b01110000,
0b00100000,
0b00100000,
0b01010000,
0b10001000};
//================================
//3x5 font numbers, then letters
//packed two per definition for fast
//copy to the screen at x-position divisible by 4
flash char smallbitmap[41][5]={
//0
0b11101110,
0b10101010,
0b10101010,
0b10101010,
0b11101110,
//1
0b01000100,
0b11001100,
0b01000100,
0b01000100,
0b11101110,
//2
0b11101110,
0b00100010,
0b11101110,
0b10001000,
0b11101110,
//3
0b11101110,
0b00100010,
0b11101110,
0b00100010,
0b11101110,
//4
0b10101010,
0b10101010,
0b11101110,
0b00100010,
0b00100010,
//5
0b11101110,
0b10001000,
0b11101110,
0b00100010,
0b11101110,
//6
0b11001100,
0b10001000,
0b11101110,
0b10101010,
0b11101110,
//7
0b11101110,
0b00100010,
0b01000100,
0b10001000,
0b10001000,
//8
0b11101110,
0b10101010,
0b11101110,
0b10101010,
0b11101110,
//9
0b11101110,
0b10101010,
0b11101110,
0b00100010,
0b01100110,
//:
0b00000000,
0b01000100,
0b00000000,
0b01000100,
0b00000000,
//=
0b00000000,
0b11101110,
0b00000000,
0b11101110,
0b00000000,
//blank
0b00000000,
0b00000000,
0b00000000,
0b00000000,
0b00000000,
//A
0b11101110,
0b10101010,
0b11101110,
0b10101010,
0b10101010,
//B
0b11001100,
0b10101010,
0b11101110,
0b10101010,
0b11001100,
//C
0b11101110,
0b10001000,
0b10001000,
0b10001000,
0b11101110,
//D
0b11001100,
0b10101010,
0b10101010,
0b10101010,
0b11001100,
//E
0b11101110,
0b10001000,
0b11101110,
0b10001000,
0b11101110,
//F
0b11101110,
0b10001000,
0b11101110,
0b10001000,
0b10001000,
//G
0b11101110,
0b10001000,
0b10001000,
0b10101010,
0b11101110,
//H
0b10101010,
0b10101010,
0b11101110,
0b10101010,
0b10101010,
//I
0b11101110,
0b01000100,
0b01000100,
0b01000100,
0b11101110,
//J
0b00100010,
0b00100010,
0b00100010,
0b10101010,
0b11101110,
//K
0b10001000,
0b10101010,
0b11001100,
0b11001100,
0b10101010,
//L
0b10001000,
0b10001000,
0b10001000,
0b10001000,
0b11101110,
//M
0b10101010,
0b11101110,
0b11101110,
0b10101010,
0b10101010,
//N
0b00000000,
0b11001100,
0b10101010,
0b10101010,
0b10101010,
//O
0b01000100,
0b10101010,
0b10101010,
0b10101010,
0b01000100,
//P
0b11101110,
0b10101010,
0b11101110,
0b10001000,
0b10001000,
//Q
0b01000100,
0b10101010,
0b10101010,
0b11101110,
0b01100110,
//R
0b11101110,
0b10101010,
0b11001100,
0b11101110,
0b10101010,
//S
0b11101110,
0b10001000,
0b11101110,
0b00100010,
0b11101110,
//T
0b11101110,
0b01000100,
0b01000100,
0b01000100,
0b01000100,
//U
0b10101010,
0b10101010,
0b10101010,
0b10101010,
0b11101110,
//V
0b10101010,
0b10101010,
0b10101010,
0b10101010,
0b01000100,
//W
0b10101010,
0b10101010,
0b11101110,
0b11101110,
0b10101010,
//X
0b00000000,
0b10101010,
0b01000100,
0b01000100,
0b10101010,
//Y
0b10101010,
0b10101010,
0b01000100,
0b01000100,
0b01000100,
//Z
0b11101110,
0b00100010,
0b01000100,
0b10001000,
0b11101110,
// characters we defined
// -
0b00000000,
0b00000000,
0b11101110,
0b00000000,
0b00000000,
// .
0b00000000,
0b00000000,
0b00000000,
0b01100110,
0b01100110
};
//==================================
//plot one point
//at x,y with color 1=white 0=black 2=invert
#pragma warn-
void video_pt(char x, char y, char c)
begin
#asm
; i=(x>>3) + ((int)y<<4) ; the byte with the pixel in it
push r16
ldd r30,y+2 ;get x
lsr r30
lsr r30
lsr r30 ;divide x by 8
ldd r12,y+1 ;get y
lsl r12 ;mult y by 16
clr r13
lsl r12
rol r13
lsl r12
rol r13
lsl r12
rol r13
add r12, r30 ;add in x/8
;v2 = screen[i]; r5
;v3 = pos[x & 7]; r6
;v4 = c r7
ldi r30,low(_screen)
ldi r31,high(_screen)
add r30, r12
adc r31, r13
ld r5,Z ;get screen byte
ldd r26,y+2 ;get x
ldi r27,0
andi r26,0x07 ;form x & 7
ldi r30,low(_pos*2)
ldi r31,high(_pos*2)
add r30,r26
adc r31,r27
lpm r6,Z
ld r16,y ;get c
;if (v4==1) screen[i] = v2 | v3 ;
;if (v4==0) screen[i] = v2 & ~v3;
;if (v4==2) screen[i] = v2 ^ v3 ;
cpi r16,1
brne tst0
or r5,r6
tst0:
cpi r16,0
brne tst2
com r6
and r5,r6
tst2:
cpi r16,2
brne writescrn
eor r5,r6
writescrn:
ldi r30,low(_screen)
ldi r31,high(_screen)
add r30, r12
adc r31, r13
st Z, r5 ;write the byte back to the screen
pop r16
#endasm
end
#pragma warn+
//==================================
// put a big character on the screen
// c is index into bitmap
void video_putchar(char x, char y, char c)
begin
v7 = x;
for (v6=0;v6<7;v6++)
begin
v1 = bitmap[c][v6];
v8 = y+v6;
video_pt(v7, v8, (v1 & 0x80)==0x80);
video_pt(v7+1, v8, (v1 & 0x40)==0x40);
video_pt(v7+2, v8, (v1 & 0x20)==0x20);
video_pt(v7+3, v8, (v1 & 0x10)==0x10);
video_pt(v7+4, v8, (v1 & 0x08)==0x08);
end
end
//==================================
// put a string of big characters on the screen
void video_puts(char x, char y, char *str)
begin
char i ;
for (i=0; str[i]!=0; i++)
begin
if (str[i]>=0x30 && str[i]<=0x3a)
video_putchar(x,y,str[i]-0x30);
else video_putchar(x,y,str[i]-0x40+9);
x = x+6;
end
end
//==================================
// put a small character on the screen
// x-cood must be on divisible by 4
// c is index into bitmap
void video_smallchar(char x, char y, char c)
begin
char mask;
i=((int)x>>3) + ((int)y<<4) ;
if (x == (x & 0xf8)) mask = 0x0f; //f8
else mask = 0xf0;
screen[i] = (screen[i] & mask) | (smallbitmap[c][0] & ~mask);
screen[i+16] = (screen[i+16] & mask) | (smallbitmap[c][1] & ~mask);
screen[i+32] = (screen[i+32] & mask) | (smallbitmap[c][2] & ~mask);
screen[i+48] = (screen[i+48] & mask) | (smallbitmap[c][3] & ~mask);
screen[i+64] = (screen[i+64] & mask) | (smallbitmap[c][4] & ~mask);
end
//==================================
// put a string of small characters on the screen
// x-cood must be on divisible by 4
void video_putsmalls(char x, char y, char *str)
begin
char i ;
for (i=0; str[i]!=0; i++)
begin
if (str[i]>=0x30 && str[i]<=0x3a && str[i]!=0x20)
video_smallchar(x,y,str[i]-0x30);
// these else if statements were added for the characters we defined
else if (str[i]==0x2d) video_smallchar(x,y,str[i]-6);
else if (str[i]==0x2e) video_smallchar(x,y,str[i]-6);
else if (str[i]==0x20) video_smallchar(x,y,str[i]-20);
else video_smallchar(x,y,str[i]-0x40+12);
x = x+4;
end
end
//==================================
//plot a line
//at x1,y1 to x2,y2 with color 1=white 0=black 2=invert
//NOTE: this function requires signed chars
//Code is from David Rodgers,
//"Procedural Elements of Computer Graphics",1985
void video_line(char x1, char y1, char x2, char y2, char c)
begin
int e;
signed char dx,dy,j2, temp;
signed char s1,s2, xchange;
signed char x,y;
x = x1;
y = y1;
dx = cabs(x2-x1);
dy = cabs(y2-y1);
s1 = csign(x2-x1);
s2 = csign(y2-y1);
xchange = 0;
if (dy>dx)
begin
temp = dx;
dx = dy;
dy = temp;
xchange = 1;
end
e = ((int)dy<<1) - dx;
for (j2=0; j2<=dx; j2++)
begin
video_pt(x,y,c) ;
if (e>=0)
begin
if (xchange==1) x = x + s1;
else y = y + s2;
e = e - ((int)dx<<1);
end
if (xchange==1) y = y + s2;
else x = x + s1;
e = e + ((int)dy<<1);
end
end
//==================================
//return the value of one point
//at x,y with color 1=white 0=black 2=invert
char video_set(char x, char y)
begin
//The following construction
//detects exactly one bit at the x,y location
i=((int)x>>3) + ((int)y<<4) ;
return ( screen[i] & 1<<(7-(x & 0x7)));
end
//==================================
//This is the sync generator and raster generator. It MUST be entered from
//sleep mode to get accurate timing of the sync pulses
#pragma warn-
interrupt [TIM1_COMPA] void t1_cmpA(void)
begin
//start the Horizontal sync pulse
PORTD = syncON;
//update the curent scanline number
LineCount ++ ;
//begin inverted (Vertical) synch after line 247
if (LineCount==248)
begin
syncON = 0b00100000;
syncOFF = 0;
end
//back to regular sync after line 250
if (LineCount==251)
begin
syncON = 0;
syncOFF = 0b00100000;
end
//start new frame after line 262
if (LineCount==263)
begin
LineCount = 1;
end
delay_us(2); //adjust to make 5 us pulses
//end sync pulse
PORTD = syncOFF;
if (LineCount<ScreenBot && LineCount>=ScreenTop)
begin
//compute byte index for beginning of the next line
//left-shift 4 would be individual lines
// <<3 means line-double the pixels
//The 0xfff8 truncates the odd line bit
//i=(LineCount-ScreenTop)<<3 & 0xfff8; //
#asm
push r16
lds r12, _LineCount
lds r13, _Linecount+1
ldi r16, 30
sub r12, r16
ldi r16,0
sbc r13, r16
lsl r12
rol r13
lsl r12
rol r13
lsl r12
rol r13
mov r16,r12
andi r16,0xf0
mov r12,r16
pop r16
#endasm
//load 16 registers with screen info
#asm
push r14
push r15
push r16
push r17
push r18
push r19
push r26
push r27
ldi r26,low(_screen) ;base address of screen
ldi r27,high(_screen)
add r26,r12 ;offset into screen (add i)
adc r27,r13
ld r4,x+ ;load 16 registers and inc pointer
ld r5,x+
ld r6,x+
ld r7,x+
ld r8,x+
ld r9,x+
ld r10,x+
ld r11,x+
ld r12,x+
ld r13,x+
ld r14,x+
ld r15,x+
ld r16,x+
ld r17,x+
ld r18,x+
ld r19,x
pop r27
pop r26
#endasm
delay_us(3); //adjust to center image on screen
//blast 16 bytes to the screen
#asm
;but first a macro to make the code shorter
;the macro takes a register number as a parameter
;and dumps its bits serially to portD.6
;the nop can be eliminated to make the display narrower
.macro videobits ;regnum
BST @0,7
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,6
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,5
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,4
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,3
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,2
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,1
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
BST @0,0
IN R30,0x12
BLD R30,6
nop
OUT 0x12,R30
.endm
videobits r4 ;video line -- byte 1
videobits r5 ;byte 2
videobits r6 ;byte 3
videobits r7 ;byte 4
videobits r8 ;byte 5
videobits r9 ;byte 6
videobits r10 ;byte 7
videobits r11 ;byte 8
videobits r12 ;byte 9
videobits r13 ;byte 10
videobits r14 ;byte 11
videobits r15 ;byte 12
videobits r16 ;byte 13
videobits r17 ;byte 14
videobits r18 ;byte 15
videobits r19 ;byte 16
clt ;clear video after the last pixel on the line
IN R30,0x12
BLD R30,6
OUT 0x12,R30
pop r19
pop r18
pop r17
pop r16
pop r15
pop r14
#endasm
end
if ((time_counter == time_offset) && (run_state < 3)) //ready for sample
begin
values[time_index++] = (ADCH>>2) + 20; // store the (adjusted) value
if (time_index == 127) time_index = 0; // start over
time_counter = 0; // start over
end
time_counter++; //increment
ADCSR.6 = 1; //starts adc
end
#pragma warn+
/********************************************/
void init_screen(void)
begin
TIMSK = 0x00; // turns off timers
for (sum=0; sum<1600; sum++)
screen[sum] = 0; // blank screen
sum = 0;
for (j=0; j<=127; j++)
begin
values[j] = 150;
values_old[j] = 150;
video_pt(j, values_old[j], 1); // draw the horizontal line at 0 to start with so we can invert later
end
video_pt(127,150,0);
//Print "DIGITAL"
video_puts(5,3,cu1);
//Print "STETHOSCOPE"
video_puts(57,3,cu2);
//Print "BPM"
video_putsmalls(4,93,cu3);
//side lines
#define tv_width 126
video_line(0,0,0,99,1);
video_line(tv_width,0,tv_width,99,1);
//top line & bottom lines
video_line(0,0,tv_width,0,1);
video_line(0,99,tv_width,99,1);
video_line(0,11,tv_width,11,1);
video_line(0,89,tv_width,89,1);
//Division line on bottom bar
video_line(40,89,40,99,1);
video_line(68,89,68,99,1);
video_line(95,89,95,99,1);
TIMSK = 0x10; // turns on timer1
end
/*********************************************/
void initialize(void)
begin
//init timer 1 to generate sync
OCR1A = lineTime; //One NTSC line
TCCR1B = 9; //full speed; clear-on-match
TCCR1A = 0x00; //turn off pwm and oc lines
TIMSK = 0x10; //enable interrupt T1 cmp
//init ports
DDRD = 0xf0; //video out and switches
//D.5 is sync:1000 ohm + diode to 75 ohm resistor
//D.6 is video:330 ohm + diode to 75 ohm resistor
DDRA = 0x00; // input from output of op-amp on A.0, A3,4 are run/stop and 1/2 sec from CPU2, A5,6 are high/low condition from CPU2
DDRC = 0x00; // bpm input from CPU2
//init ADC stuff
ADMUX = 0b01100000; // ADLAR = 1, read only from ADCH (low 2 bits in ADCL)
// read from channel 0, single ended
ADCSR = 0b10000110; // 7: ADenable, 6: ADstart, 5: freerun, 4: ADdone INT flag
// 3: AD INT enable, 2-0: clk
// (110 -> 250KHz AD Clk; 19.2KHz effective sample rate)
time_counter = 1;
time_offset = 120; // start at 1 sec timing
time_index = 0;
run_state = 1; // start on 1 sec
/* run_state:
5: off 1 sec
6: off 2 sec
1: run 1 sec
2: run 2 sec */
//init the scren
init_screen();
//initialize synch constants
LineCount = 1;
syncON = 0b00000000;
syncOFF = 0b00100000;
//init software timer
t=0;
time=0;
//enable sleep mode
MCUCR = 0b10000000;
#asm ("sei");
end
//==================================
// set up the ports and timers
void main(void)
begin
initialize();
ADCSR.6 = 1; // turn on ADC
//The following loop executes once/video line during lines
//1-230, then does all of the frame-end processing
while(1)
begin
#asm ("sleep");
//a total of 60 lines x 63.5 uSec/line x 16 cycles/uSec
if (LineCount == 231)
begin
if (run_state < 3) // running
begin
// blast the values
for (j=1; j<126; j++)
begin
video_pt(j,values_old[j],2); //clear the old points
video_pt(j,values[j],2); // write the new points
values_old[j] = values[j]; // save the values to be cleared next frame
end
if (PINA.3 == 0) // stop button pressed
begin
if (run_state == 1) run_state = 5; // if stop is pressed then stop (in 1sec)
else run_state = 6; // stop in 2 sec mode
end // stop test
end // if running
else // stopped
begin
if (PINA.3 == 1) // if turned off and run button pressed, start
begin
if (run_state == 5) run_state = 1; // run in 1sec
else run_state = 2; //run in 2sec
init_screen(); // to clear screen
end
if (PINA.4 == 0) // put in 2 sec mode
begin
time_offset = 240; // set the time offset for timing width
// print 2sec on bottom of screen
video_smallchar(72,93,2);
video_putsmalls(76,93,sec);
end
if (PINA.4 == 1) // put in 1 sec mode
begin
time_offset = 120; // set the time offset for timing width
//print 1sec on bottom of screen
video_smallchar(72,93,1);
video_putsmalls(76,93,sec);
end
end // if turned off
//update the second clock
if (++t>59)
begin
//indicate high/low condition on screen
if (PINA.5 == 1) video_putsmalls(44,93,hl3); // "LOW"
else if (PINA.6 == 1) video_putsmalls(44,93,hl2); // "HIGH"
else if (PINC == 0x00) video_putsmalls(44,93,hl4); // "ERR"
else video_putsmalls(44,93,hl1); // "OK"
//put the bpm (portC) on the screen
bpm = PINC;
sprintf(ts,"%03d",bpm);
video_putsmalls(20,93,ts);
// update timer on screen
t=0;
time = time + 1;
sprintf(ts,"%05d",time);
video_putsmalls(100,93,ts);
end
end //line 231
end //while
end //main
CPU2
//************************************************************
// EE 476 FINAL PROJECT CPU2 CODE
// Aaron Davis (amd43) and Brandon Richter (bcr5)
//************************************************************
//include necessary files
#include <Mega32.h>
#include <stdio.h>
#include <delay.h>
#include <stdlib.h>
//timeout values for each task
#define t1 50
#define t2 2
#define begin {
#define end }
//define pushstates
#define NoPush 1
#define MaybePush 2
#define Pushed 3
#define MaybeNoPush 4
//define modes
#define mode1 1
#define mode2 2
//define # samples for bpm calculation
#define numSamps 1000
char b0_PushState, b1_PushState, b2_PushState, b3_PushState,b5_PushState,b6_PushState,b7_PushState;
char b5_PushFlag,b6_PushFlag,b7_PushFlag;
//the task subroutines
void initialize(void);
void debounce(void);
void detect(void);
unsigned char time1,time2;
char mode,mute,stopgo; //variables for modes in statemachine
unsigned char Ain; //voltage from output of op-amp
unsigned char max_value; //used for peak detection
int start, stop; //variables for bpm calculation
unsigned int i; //loop variable
unsigned char bpm, low, high; //bpm, low violation value, high violation value
int arr_index; //array index for values array
float alpha; //digital lpf parameter
char values[numSamps]; // store 1000 adc values taken every 2ms for 2 sec of data
//**********************************************************
//timer 0 compare ISR
interrupt [TIM0_COMP] void timer0_compare(void)
begin
//Decrement the times if it is not already zero
if (time1>0) --time1;
if (time2>0) --time2;
end
//**********************************************************
//Entry point and task scheduler loop
void main(void)
begin
initialize();
while (1)
begin
if (time1==0) debounce(); // run the state machine
if(time2==0)
begin
time2 = t2; // update t2
values[arr_index++]= ADCH; //get value
ADCSR.6 = 1; //start next adc
end
if (arr_index-1 == numSamps) //values array is full
begin
detect(); // calculate bpm
arr_index = 0; // start at beginning of values array
end
//send messages to cpu1 to be displayed on screen if there is a low or high violation
if((bpm<low) && (bpm != 0)) PORTA.5 = 1; //low violation
else PORTA.5 = 0; // no low violation
if(bpm>high) PORTA.6 = 1; // high violation
else PORTA.6 = 0; // no high violation
//turn on buzzer when appropriate
if ( ((bpm<low)||(bpm>high)) && (bpm != 0) && (mute==mode2) )
PORTA.7=1; //buzzer on
else PORTA.7=0; //buzzer off
//output BPM
PORTC = bpm;
end
end
//**********************************************************
//calculate bpm
void detect(void)
begin
TCCR0=0; //turn off timer0 interrupt
alpha = 0.8; // set LPF parameter
for (i=1;i<numSamps;i++)
begin
values[i] = (char)(255- (alpha*values[i] + (1-alpha)*values[i-1])); //flip and digital LPF
end
// find max in values
max_value = 0;
for(i=0;i<numSamps;i++)
begin
if(values[i]>max_value) max_value=values[i];
end
//find 1st point where values becomes > (0.8)*max_value
start=0;
for(i=7;i<numSamps;i++)
begin
if(start!=0) break;
if(values[i]>values[i-6]) //increasing
begin
if(values[i] > 128 + (max_value-128)*.8) start=i; // >(0.8)*max_value
end
end
//find next point where values crosses (0.8)*max_values
// note:skip 150 values, which corresponds to 0.3 sec of data, before staring to look for stop in case of noise
stop=0;
for(i=start+150;i<numSamps;i++)
begin
if(stop!=0) break;
if(values[i]>values[i-6]) //increasing
begin
if((values[i]) > 128 + (max_value-128)*.8) stop=i; // <(0.8*max_value
end
end
if (max_value<135) // no beat threshold
begin
start = 0;
stop = 0;
end
//calculate bpm
if((start!=0) && (stop!=0))
bpm = (char)(60/(.002*(stop-start))); // calculation for bpm
else if ((start==0) && (stop==0)) bpm = 0; // no peak detected
//put the info to the hyperterm
printf("Max: %d Start: %d Start: %d\r\n", max_value, start, stop);
if (mute==mode2) printf("Buzzer on\r\n"); else printf("Buzzer Muted\r\n");
if (stopgo==mode1) printf("Monitor Running"); else printf("Monitor off");
if (mode==mode1) printf(" 1 second\r\n"); else printf(" 2 second\r\n");
printf("Low Value: %d High Value: %d \r\n", low,high);
printf("Current BPM: %d", bpm);
printf("\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n");
TCCR0=0b00001011;
end
//**********************************************************
//debounce state machine
void debounce(void)
begin
time1 = t1;
switch (b0_PushState) // decrease low
begin
case NoPush:
if (~PINB == 0b00000001)
b0_PushState = MaybePush;
else
b0_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b00000001)
b0_PushState = Pushed;
else
b0_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b00000001)
begin
b0_PushState = Pushed;
low--;
end
else
b0_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b00000001)
b0_PushState = Pushed;
else
b0_PushState = NoPush;
break;
end
switch (b1_PushState) // increase low
begin
case NoPush:
if (~PINB == 0b00000010)
b1_PushState = MaybePush;
else
b1_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b00000010)
b1_PushState = Pushed;
else
b1_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b00000010)
begin
b1_PushState = Pushed;
low++;
end
else
b1_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b00000010)
b1_PushState = Pushed;
else
b1_PushState = NoPush;
break;
end
switch (b2_PushState) // decrease high
begin
case NoPush:
if (~PINB == 0b00000100)
b2_PushState = MaybePush;
else
b2_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b00000100)
b2_PushState = Pushed;
else
b2_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b00000100)
begin
b2_PushState = Pushed;
high--;
end
else
b2_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b00000100)
b2_PushState = Pushed;
else
b2_PushState = NoPush;
break;
end
switch (b3_PushState) // increase high
begin
case NoPush:
if (~PINB == 0b00001000)
b3_PushState = MaybePush;
else
b3_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b00001000)
b3_PushState = Pushed;
else
b3_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b00001000)
begin
b3_PushState = Pushed;
high++;
end
else
b3_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b00001000)
b3_PushState = Pushed;
else
b3_PushState = NoPush;
break;
end
switch (b5_PushState) // mute for buzzer: mode1=mute, mode2=buzzer on
begin
case NoPush:
if (~PINB == 0b00100000)
b5_PushState = MaybePush;
else
b5_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b00100000)
b5_PushState = Pushed;
else
b5_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b00100000)
begin
b5_PushState = Pushed;
if (b5_PushFlag == 0)
begin
if (mute == mode1)
mute = mode2;
else
mute = mode1;
b5_PushFlag = 1;
end
end
else
b5_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b00100000)
b5_PushState = Pushed;
else
begin
b5_PushState = NoPush;
b5_PushFlag = 0;
end
break;
end
switch (b6_PushState) // toggle 1 or 2 sec mode: mode1=1sec, mode2=2sec
begin
case NoPush:
if (~PINB == 0b01000000)
b6_PushState = MaybePush;
else
b6_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b01000000)
b6_PushState = Pushed;
else
b6_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b01000000)
begin
b6_PushState = Pushed;
if (b6_PushFlag==0)
begin
if (mode == mode1)
mode = mode2;
else
mode = mode1;
b6_PushFlag = 1;
end
end
else
b6_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b01000000)
b6_PushState = Pushed;
else
begin
b6_PushState = NoPush;
b6_PushFlag = 0;
end
break;
end
switch (b7_PushState) // toggle on/off: mode1=run, mode2=stop
begin
case NoPush:
if (~PINB == 0b10000000)
b7_PushState = MaybePush;
else
b7_PushState = NoPush;
break;
case MaybePush:
if (~PINB == 0b10000000)
b7_PushState = Pushed;
else
b7_PushState = NoPush;
break;
case Pushed:
if (~PINB == 0b10000000)
begin
b7_PushState = Pushed;
if (b7_PushFlag == 0)
begin
if(stopgo == mode1)
stopgo = mode2;
else
stopgo = mode1;
b7_PushFlag = 1;
end
end
else
b7_PushState = MaybeNoPush;
break;
case MaybeNoPush:
if (~PINB == 0b10000000)
b7_PushState = Pushed;
else
begin
b7_PushState = NoPush;
b7_PushFlag = 0;
end
break;
end
//send info to CPU1
if (stopgo == mode1) PORTA.3 = 1; //run
else PORTA.3 = 0; //stop
if (mode == mode1) PORTA.4 = 1; //1sec
else PORTA.4 = 0; //2sec
end
//**********************************************************
//Set it all up
void initialize(void)
begin
// set up the ports
DDRB=0x00; // PORT B is button inputs
DDRA=0b11111110; // PORT A.0 is input from stethoscope, A1-7 are output
DDRC=0xff; // PORT C is output to cpu1
// set up timer 0
TIMSK=2; //turn on timer 0 cmp match ISR, and T1 cmp match A ISR
OCR0 = 250; //set the compare reg to 250 time ticks, giving a 1ms time interval for interrupts
//prescalar to 64 and turn on clear-on-match
TCCR0=0b00001011;
// init ADC stuff
ADMUX = 0b11100000; // ADLAR = 1, read only from ADCH (low 2 bits in ADCL)
// read from channel 0, single ended
ADCSR = 0b10000111; // 7: ADenable, 6: ADstart, 5: freerun, 4: ADdone INT flag
// 3: AD INT enable, 2-0: clk
// (110 -> 250KHz AD Clk; 19.2KHz effective sample rate)
// (111 -> 125KHz AD Clk; 9.6KHz effective sample rate)
// init the task timer
time1=t1;
time2=0;
// init mode
mode = mode1; //1sec mode
stopgo = mode1; //run
mute = mode1; //muted
// init the state variables
b0_PushState = NoPush; b1_PushState = NoPush; b2_PushState = NoPush; b3_PushState = NoPush; b5_PushState = NoPush; b6_PushState = NoPush; b7_PushState = NoPush;
b5_PushFlag = 0; b6_PushFlag = 0; b7_PushFlag = 0;
//initialize high/low violation values
low = 50;
high = 100;
//initialize bpm
bpm=0;
// initialize these variables to 0
Ain =0;
max_value=0;
start=0;
stop=0;
i=0;
arr_index = 0;
//init the UART
UCSRB = 0b00011000; // enable Tx and Rx (no ints)
UBRRL = 103; // using a 16 MHz crystal (9600 baud)
putsf("Program Starting!!!\r\n\r\n"); // print to hyperterm when starting
//crank up the ISRs
#asm
sei
#endasm
end
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