4 years, 11 months ago.

ultrasonic sensor

Could any one help me with some questions? thanks!! I want to measure distance using an ultrasonic sensor and print the measurement on LCD. I have finished the code but it has some problems and the most serious one is that it cannot return a number from the sensor. I think LCD does not have problems because it can print the words "the distance is". Below is my code.

1. include "mbed.h"
2. include"TextLCD.h"

float distance(){ float time_us; Timer timer; float distance; AnalogIn echoin(A2); AnalogOut trigout(A1); trigout=1; wait_us(50); trigout=0; pulsein

while(echoin==0); timer.start(); while(echoin==1); timer.stop(); time_us=timer.read_us(); distance=(time_us*34/100)/2; timer.reset(); return distance; }

int main(){ float a=0; TextLCD lcd (D2,D3,D9,D10,D11,D12); rs,e,d0,d1,d2,d3 lcd.printf("the distance is"); while(1){ a=distance(); lcd.locate(1,1); lcd.printf("aaa"); lcd.printf("%f mm",a); wait(0.3); } }