I have a raspberry Pi that has the particle-agent installed, and i have been trying to get the HC-SR04 to work on. i have been following this guide by @rocksetta (Ultrasonic range finder simple code).
//using Ultrasonic Range Finder from Robotshop
unsigned long duration;
// ultrasonic range finder Robotshop RB-lte-54
// GND pin goes to ground
pinMode(D11, INPUT); // echo
pinMode(D10, OUTPUT); // Trig
// VCC pin goes to VIN on the photon
delay(1000);// even cicuits need a break
duration = pulseIn(D11, LOW); // how long until a reply?
// a blocking call so may wait a few seconds
The output from this code always returns “0” no matter what i put, i even tried delayMicroseconds(); instead of delay but still no results. i tested the code on an Arduino and the sensor works great, but on the particle-agent it does not. Am I doing something wrong? I’ve tried everything that i can think of, not sure whats next.
Have you tried using the library function
HC_SR04? Looking at the code snippet the pulse length seems long 1000 microSeconds whereas the library uses 10 microSeconds and the duration calculation is returning a distance - maybe what you want rather than duration of pulse!
Hey! Thanks for the reply @armor , i have also tried it, i had the same results. and i did try shorter time periods
The problem is that pulseIn is not supported on the Raspberry Pi. You’ll need to implement it by hand by polling the pin for change and measuring times.
@rickkas7 That’s good point, which I wasn’t sure about - however the library HC_SR04 does not use pulseIn().
@karam Have you tried voltage splitting the echo pin as recommended (I am not certain about RPi - photon does not work unless voltage split using 2 470ohm resistors. Also, are you sure that the pins are connected correctly to the RPi header (and is the pin compatible with digital I/O). Software wise, pinSetFast() and pinReadFast() are more appropriate for fast switching and reading (not sure if these are implemented in RPi).
@armor hey! Sorry about the later reply, but I have tried other methods including the ones stated above, and still no results. I was thinking making particle trigger a python script and get the results back, not really sure how to make it do that yet, any suggestions or tips on how that would work? I have found the source where you can call a function and it will return a value back. I did that using the command that gives you the cpu temp back, but couldn’t get it to run my own script.