Temperature sensor not working [closed] - c

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Greetins,
I recently bought a temperature & humidity sensor (aosong am2302). I hooked it to a rasp pi 3 and it works like charm with the adafruit library. The problem comes when i try to make it work on another board (described here). I used this library for gpio reading. I modified the file of beaglebone for gpio mapping and that's it. I run the tests and they work, so basically the lib looks like it works. So after that, I code the sensor reader and it doesnt work and I dont know why.
After I run the sensor reader, If I check the file system, the gpio is exported.
The sensor is installed like this:
-Power to 5V (also tried with 3.3v)
-VCC to gpio
-Ground to GND.
and here the code
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/wait.h>
#include <sys/time.h>
#include "libsoc_gpio.h" //library for gpio reading
#define MAXTIMINGS 10
#define SILENT 0
int bits[MAXTIMINGS+1],data[5];
int readDHT(int pin,int allowRetry);
int
main(int argc, char **argv)
{ int dhtpin;
if (argc>1)dhtpin=atoi(argv[1]);
else printf("Introduce pin");
if( SILENT < 1 ) {
printf("Using pin #%d\n", dhtpin);
}
readDHT(dhtpin,5);
return 0;
}
int
readDHT(int pin, int allowRetry)
{
int bitidx=0;
int counter = 0;
int i=0,j=0;
data[0] = data[1] = data[2] = data[3] = data[4] = 0;
gpio *gpio_output = libsoc_gpio_request(pin, LS_SHARED); //export GPIO
if (gpio_output == NULL)
{
fprintf(stderr, "Failed to open GPIO %d\n", pin);
return -1;
}
libsoc_gpio_set_direction(gpio_output, OUTPUT);
if (libsoc_gpio_get_direction(gpio_output) != OUTPUT)
{
fprintf(stderr, "Failed to set direction to OUTPUT\n");
if (gpio_output)
{
libsoc_gpio_free(gpio_output);
}
return -1;
}
libsoc_gpio_set_level(gpio_output, LOW);
libsoc_gpio_set_level(gpio_output, HIGH);
libsoc_gpio_set_direction(gpio_output, INPUT);
/* Wait for pin to drop */
while (libsoc_gpio_get_level(gpio_output) == HIGH)
{
if(counter++>10000){
printf("ERROR: Pin never dropped\n");
return 1;
}
}
if (i<= MAXTIMINGS)
{
counter =0;
while (libsoc_gpio_get_level(gpio_output) == LOW){
if(counter++ == 1000)
break;
}
counter =0;
while(libsoc_gpio_get_level(gpio_output) == HIGH){
if (counter++==1000)
break;
}
bits[bitidx++] = counter;
i++;
}
/* read data */
for (i = 1; i < bitidx; i++) {
data[j / 8] <<= 1;
if(bits[i]>200){
data[j/8] |= 1;
}
j++;
}
if( SILENT < 1 ) {
printf("Data (%d): 0x%x 0x%x 0x%x 0x%x 0x%x\n", j, data[0], data[1], data[2], data[3], data[4]);
}
if ((j >= 39) && (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) ) {
float f, h;
h = data[0] * 256 + data[1];
h /= 10;
f = (data[2] & 0x7F)* 256 + data[3];
f /= 10.0;
if (data[2] & 0x80) f *= -1;
printf("CTemp: %.1f\nFTemp: %.1f\nHum: %.1f%\n", f, ((f*9)/5)+32, h);
} else if( allowRetry > 0 ) {
sleep(1);
if( SILENT < 1 ) {
printf( "Error getting information. Retrying\n" );
}
return readDHT(pin, --allowRetry );
} else {
if( SILENT < 1 ) {
printf( "Error getting information. Retries exhausted.\n" );
}
return 1;
}
return 0;
if (gpio_output)
{
libsoc_gpio_free(gpio_output);
}
/* Check we got all the data and checksum matches */
}
With this code I get "Pin never dropped", so pin never goes to 0 so it doesnt report data. So i decided to try with bash and see if pin drops to 0. I coded the same as on the previous code but in bash and see the value of the pin (always 1, not dropping). Comming to this point, I run out of options, the sensor works (it's not broken), the library works but the sensor on this machine no. Any clue or idea on how to approach to find a solution?
Thanks :)

Answer 1

Some things to try that might get you going....
First increase the counter "counter++>10000" to something much larger, It could be that the new processor you are running increments the counter at a much faster rate and you just timeout before the pin drops.
If that doesn't work remove the timeout counter and loop forever in your source, also remove the sensor, then physically pull the data line to ground with a piece of wire and see if your code/new processor catches the signal change, at least then you know your source/hardware is configured correctly so you can focus your efforts elsewhere.
Double check the voltage compatibility between your new processor 'high' level and what the sensors 'high' threshold is to ensure it is catching a 'one' on the data line.
Lettus know how you go!
Tony