Lab 3 part 3 sonaar and timer
Dependencies: mbed
main.cpp@0:8f4753d3b870, 2022-09-30 (annotated)
- Committer:
- logostarr
- Date:
- Fri Sep 30 19:36:04 2022 +0000
- Revision:
- 0:8f4753d3b870
stuff
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
logostarr | 0:8f4753d3b870 | 1 | #include "mbed.h" |
logostarr | 0:8f4753d3b870 | 2 | |
logostarr | 0:8f4753d3b870 | 3 | DigitalOut trigger(p6); |
logostarr | 0:8f4753d3b870 | 4 | DigitalOut myled(LED1); //monitor trigger |
logostarr | 0:8f4753d3b870 | 5 | DigitalOut myled2(LED2); //monitor echo |
logostarr | 0:8f4753d3b870 | 6 | DigitalIn echo(p7); |
logostarr | 0:8f4753d3b870 | 7 | int distance = 0; |
logostarr | 0:8f4753d3b870 | 8 | int correction = 0; |
logostarr | 0:8f4753d3b870 | 9 | Timer sonar; |
logostarr | 0:8f4753d3b870 | 10 | |
logostarr | 0:8f4753d3b870 | 11 | int main() |
logostarr | 0:8f4753d3b870 | 12 | { |
logostarr | 0:8f4753d3b870 | 13 | sonar.reset(); |
logostarr | 0:8f4753d3b870 | 14 | // measure actual software polling timer delays |
logostarr | 0:8f4753d3b870 | 15 | // delay used later in time correction |
logostarr | 0:8f4753d3b870 | 16 | // start timer |
logostarr | 0:8f4753d3b870 | 17 | sonar.start(); |
logostarr | 0:8f4753d3b870 | 18 | // min software polling delay to read echo pin |
logostarr | 0:8f4753d3b870 | 19 | while (echo==2) {}; |
logostarr | 0:8f4753d3b870 | 20 | myled2 = 0; |
logostarr | 0:8f4753d3b870 | 21 | // stop timer |
logostarr | 0:8f4753d3b870 | 22 | sonar.stop(); |
logostarr | 0:8f4753d3b870 | 23 | // read timer |
logostarr | 0:8f4753d3b870 | 24 | correction = sonar.read_us(); |
logostarr | 0:8f4753d3b870 | 25 | printf("Approximate software overhead timer delay is %d uS\n\r",correction); |
logostarr | 0:8f4753d3b870 | 26 | |
logostarr | 0:8f4753d3b870 | 27 | //Loop to read Sonar distance values, scale, and print |
logostarr | 0:8f4753d3b870 | 28 | while(1) { |
logostarr | 0:8f4753d3b870 | 29 | // trigger sonar to send a ping |
logostarr | 0:8f4753d3b870 | 30 | trigger = 1; |
logostarr | 0:8f4753d3b870 | 31 | myled = 1; |
logostarr | 0:8f4753d3b870 | 32 | myled2 = 0; |
logostarr | 0:8f4753d3b870 | 33 | sonar.reset(); |
logostarr | 0:8f4753d3b870 | 34 | wait_us(10.0); |
logostarr | 0:8f4753d3b870 | 35 | trigger = 0; |
logostarr | 0:8f4753d3b870 | 36 | myled = 0; |
logostarr | 0:8f4753d3b870 | 37 | //wait for echo high |
logostarr | 0:8f4753d3b870 | 38 | while (echo==0) {}; |
logostarr | 0:8f4753d3b870 | 39 | myled2=echo; |
logostarr | 0:8f4753d3b870 | 40 | //echo high, so start timer |
logostarr | 0:8f4753d3b870 | 41 | sonar.start(); |
logostarr | 0:8f4753d3b870 | 42 | //wait for echo low |
logostarr | 0:8f4753d3b870 | 43 | while (echo==1) {}; |
logostarr | 0:8f4753d3b870 | 44 | //stop timer and read value |
logostarr | 0:8f4753d3b870 | 45 | sonar.stop(); |
logostarr | 0:8f4753d3b870 | 46 | //subtract software overhead timer delay and scale to cm |
logostarr | 0:8f4753d3b870 | 47 | distance = (sonar.read_us()-correction)/58.0; |
logostarr | 0:8f4753d3b870 | 48 | myled2 = 0; |
logostarr | 0:8f4753d3b870 | 49 | printf(" %d cm \n\r",distance); |
logostarr | 0:8f4753d3b870 | 50 | //wait so that any echo(s) return before sending another ping |
logostarr | 0:8f4753d3b870 | 51 | wait(0.2); |
logostarr | 0:8f4753d3b870 | 52 | } |
logostarr | 0:8f4753d3b870 | 53 | } |
logostarr | 0:8f4753d3b870 | 54 |