ESP8266 Community Forum

- Fri Jun 17, 2016 3:56 am #49319 Hey guys,

hope you can help me. I have an ESP8266 nodeMCU ver 1.0 and try to read a preasure sensor BMP180. I have connected GND and 3V3 in the obvious way and SCL to SD3 and SDA to SD2. According to a pinout found on the internet these correspond to GPIO9 and 10. To keep it simple I just used the example of the Adafruit BMP085 lib and added the command to start I2C on the pins:

Code: Select all#include <Wire.h>
#include <Adafruit_BMP085.h>

/***************************************************
  This is an example for the BMP085 Barometric Pressure & Temp Sensor

  Designed specifically to work with the Adafruit BMP085 Breakout
  ----> https://www.adafruit.com/products/391

  These displays use I2C to communicate, 2 pins are required to
  interface
  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ****************************************************/

// Connect VCC of the BMP085 sensor to 3.3V (NOT 5.0V!)
// Connect GND to Ground
// Connect SCL to i2c clock - on '168/'328 Arduino Nano/Uno/Duemilanove/etc thats Analog 5
// Connect SDA to i2c data - on '168/'328 Arduino Nano/Uno/Duemilanove/etc thats Analog 4
// EOC is not used, it signifies an end of conversion
// XCLR is a reset pin, also not used here

Adafruit_BMP085 bmp;

void setup() {
  Wire.begin(9, 10);
  Serial.begin(9600);
  if (!bmp.begin()) {
    Serial.println("Could not find a valid BMP085 sensor, check wiring!");
    while (1) {}
  }
}

void loop() {
  Serial.print("Temperature = ");
  Serial.print(bmp.readTemperature());
  Serial.println(" *C");

  Serial.print("Pressure = ");
  Serial.print(bmp.readPressure());
  Serial.println(" Pa");

  // Calculate altitude assuming 'standard' barometric
  // pressure of 1013.25 millibar = 101325 Pascal
  Serial.print("Altitude = ");
  Serial.print(bmp.readAltitude());
  Serial.println(" meters");

  // you can get a more precise measurement of altitude
  // if you know the current sea level pressure which will
  // vary with weather and such. If it is 1015 millibars
  // that is equal to 101500 Pascals.
  Serial.print("Real altitude = ");
  Serial.print(bmp.readAltitude(101500));
  Serial.println(" meters");

  Serial.println();
  delay(500);
}


When running this code I can't see anything on serial monitor in the arduino IDE with 9600 Baud. On 115200 Baud I see repeading this:

Code: Select all ets Jan  8 2013,rst cause:4, boot mode:(3,6)

wdt reset
load 0x4010f000, len 1264, room 16
tail 0
chksum 0x0f
csum 0x0f
~ld

 ets Jan  8 2013,rst cause:4, boot mode:(3,6)

wdt reset
load 0x4010f000, len 1264, room 16
tail 0
chksum 0x0f
csum 0x0f
~ld

 ets Jan  8 2013,rst cause:4, boot mode:(3,6)

wdt reset
load 0x4010f000, len 1264, room 16
tail 0
chksum 0x0f
csum 0x0f
~ld


It seems to be connected with starting the I2C, because I get the same problem when trying a Si7021 temperature sensor. Running other code (without I2C) works fine.

If anyone can help this would be great.

Regards,
Anduril