A program that demonstrates the development of library, using as an example an ultrasonic distance sensor HC-SR04.
Dependencies: mbed HCSR04 AutomationElements
main.cpp
- Committer:
- tbjazic
- Date:
- 2015-12-03
- Revision:
- 0:ebee649c5b1b
- Child:
- 1:22043b67c31c
File content as of revision 0:ebee649c5b1b:
/** Initial test of the ultrasonic sensor HC-SR04 */ #include "mbed.h" Serial pc(USBTX, USBRX); // communication with terminal InterruptIn echo(p5); // echo pin DigitalOut trigger(p7); // trigger pin Timer timer; // echo pulsewidth measurement /** Start the echo pulsewidth measurement */ void startTimer() { timer.start(); // start the timer } /** Stop the echo pulsewidth measurement */ void stopTimer() { timer.stop(); // stop the timer } int main() { /** configure the rising edge to start the timer */ echo.rise(&startTimer); /** configure the falling edge to stop the timer */ echo.fall(&stopTimer); while(1) { /** Start the measurement by sending the 10us trigger pulse */ trigger = 1; wait_us(10); trigger = 0; /** Wait for the sensor to finish measurement (generate rise and fall interrupts). * Minimum wait time is determined by maximum measurement distance of 400 cm. * t_min = 400 * 58 = 23200 us = 23.2 ms */ wait(1); /** calculate the distance in cm */ float distance = timer.read() * 1e6 / 58; timer.reset(); // reset the timer to 0 /** Print the result in cm to the terminal with 1 decimal place * (number 5 after % means that total of 5 digits will be reserved * for printing the number, including the dot and one decimal place). */ pc.printf("Distance: %5.1f cm\r", distance); } }