Connecting a OneWire device (DS18B20) does not work
Posted: Tue Nov 24, 2015 10:53 amThis is my first serious Arduino/ESP8266 project so please bear with me...
I am trying to get a DS18B20 temperature sensor working win an ESP8266. I have wired the sensor on my breadboard with the required resistor (tried both 2.2K Ohm and 3.7K Ohm). Everything is working fine when I connect an Arduino to the breadboard (ground, +3.3V, and data pin 2) in combination with the example code that comes with the OneWire library.
The board I am using is this one (I bought two of them, both behave exactly the same):
http://www.aliexpress.com/item/V3-Wirel ... 17059.html
Here is a picture of my breadboard setup:
http://home.spelplein.eu/onewire.jpg
As mentioned above, if I connect the wires that are now connected to D2, 3V3, and GND to the equivalent Arduino pins the Arduino can read the temperature sensor just fine.
I use the Arduino IDE in combination with esp8266 board manager. This works great! Except when I wire this board up to the breadboard instead of my Arduino. I quadruple checked that I use the OneWire library and example that come with the ESP8266 board manager. I even added prints in the library to see where things go south.
This is what my minimalistic sketch looks like:
Note that I renamed the OneWire library to make sure I use the right one. I cut out all the stuff after this code in the example because this code already fails. The output shows a continuous stream of "No more addresses.".
The 'OneWire::reset' method (called from the OneWire::search method) always returns false. This is the method straight from the ESP8266 OneWire library:
The last DIRECT_READ always returns TRUE, making r false and the method fail.
Do you have any idea what I am doing wrong?
I am trying to get a DS18B20 temperature sensor working win an ESP8266. I have wired the sensor on my breadboard with the required resistor (tried both 2.2K Ohm and 3.7K Ohm). Everything is working fine when I connect an Arduino to the breadboard (ground, +3.3V, and data pin 2) in combination with the example code that comes with the OneWire library.
The board I am using is this one (I bought two of them, both behave exactly the same):
http://www.aliexpress.com/item/V3-Wirel ... 17059.html
Here is a picture of my breadboard setup:
http://home.spelplein.eu/onewire.jpg
As mentioned above, if I connect the wires that are now connected to D2, 3V3, and GND to the equivalent Arduino pins the Arduino can read the temperature sensor just fine.
I use the Arduino IDE in combination with esp8266 board manager. This works great! Except when I wire this board up to the breadboard instead of my Arduino. I quadruple checked that I use the OneWire library and example that come with the ESP8266 board manager. I even added prints in the library to see where things go south.
This is what my minimalistic sketch looks like:
Code: Select all
#include <ESP8266OneWire.h>
OneWire ds(2); // on pin 2 (a 4.7K resistor is necessary)
void setup(void) {
Serial.begin(9600);
}
void loop(void) {
byte addr[8];
if ( !ds.search(addr)) {
Serial.println("No more addresses.");
Serial.println();
ds.reset_search();
delay(250);
return;
}
Serial.println("search ok.");
delay(2000);
}
Note that I renamed the OneWire library to make sure I use the right one. I cut out all the stuff after this code in the example because this code already fails. The output shows a continuous stream of "No more addresses.".
The 'OneWire::reset' method (called from the OneWire::search method) always returns false. This is the method straight from the ESP8266 OneWire library:
Code: Select all
uint8_t OneWire::reset(void)
{
IO_REG_TYPE mask = bitmask;
volatile IO_REG_TYPE *reg IO_REG_ASM = baseReg;
uint8_t r;
uint8_t retries = 125;
noInterrupts();
DIRECT_MODE_INPUT(reg, mask);
interrupts();
// wait until the wire is high... just in case
do {
if (--retries == 0) return 0;
delayMicroseconds(2);
} while ( !DIRECT_READ(reg, mask));
noInterrupts();
DIRECT_WRITE_LOW(reg, mask);
DIRECT_MODE_OUTPUT(reg, mask); // drive output low
interrupts();
delayMicroseconds(480);
noInterrupts();
DIRECT_MODE_INPUT(reg, mask); // allow it to float
delayMicroseconds(70);
r = !DIRECT_READ(reg, mask);
interrupts();
delayMicroseconds(410);
return r;
}
The last DIRECT_READ always returns TRUE, making r false and the method fail.
Do you have any idea what I am doing wrong?