I am trying to read temp and humidity from a DHT22 using an ESP8266. I have tried nearly every DHT library I can find, and I either get nan or a timeout depending on the implementation. I have also tried using DC power with a step down to deliver 5v to the DHT22 with no luck. However, when I wire it up and run it on an Uno it works just fine.
My sensor says no pull-up resistor is needed (already on board), but I have tried that also because the product info doesn't always match the actual product.
Below are my wiring diagrams showing what does and does not work. The ESP8266 in the images isn't exactly the one I have - mine is a D1 Mini.
And here is some code that works on the Uno but not on the ESP8266:
#include "DHTStable.h"
DHTStable DHT;
#define DHT22_PIN 2
struct
{
uint32_t total;
uint32_t ok;
uint32_t crc_error;
uint32_t time_out;
uint32_t connect;
uint32_t ack_l;
uint32_t ack_h;
uint32_t unknown;
} counter = { 0,0,0,0,0,0,0,0};
void setup()
{
Serial.begin(115200);
Serial.println(__FILE__);
Serial.print("LIBRARY VERSION: ");
Serial.println(DHTSTABLE_LIB_VERSION);
Serial.println();
Serial.println("Type,\tstatus,\tHumidity (%),\tTemperature (C)\tTime (us)");
}
void loop()
{
Serial.print("DHT22, \t");
uint32_t start = micros();
int chk = DHT.read22(DHT22_PIN);
uint32_t stop = micros();
counter.total++;
switch (chk)
{
case DHTLIB_OK:
counter.ok++;
Serial.print("OK,\t");
break;
case DHTLIB_ERROR_CHECKSUM:
counter.crc_error++;
Serial.print("Checksum error,\t");
break;
case DHTLIB_ERROR_TIMEOUT:
counter.time_out++;
Serial.print("Time out error,\t");
break;
default:
counter.unknown++;
Serial.print("Unknown error,\t");
break;
}
// DISPLAY DATA
Serial.print(DHT.getHumidity(), 1);
Serial.print(",\t");
Serial.print(DHT.getTemperature(), 1);
Serial.print(",\t");
Serial.print(stop - start);
Serial.println();
// DISPLAY COUNTERS
if (counter.total % 20 == 0)
{
Serial.println("\nTOT\tOK\tCRC\tTO\tUNK");
Serial.print(counter.total);
Serial.print("\t");
Serial.print(counter.ok);
Serial.print("\t");
Serial.print(counter.crc_error);
Serial.print("\t");
Serial.print(counter.time_out);
Serial.print("\t");
Serial.print(counter.connect);
Serial.print("\t");
Serial.print(counter.ack_l);
Serial.print("\t");
Serial.print(counter.ack_h);
Serial.print("\t");
Serial.print(counter.unknown);
Serial.println("\n");
}
delay(2000);
}