Hi folks,
I'm trying to get a BME280 sensor working with my NodeMCU-32S. This is the sensor I have.
I have the sensor wired up thuswise:
3.3V -> VIN
GND -> GND
P22 -> SCL
P21 -> SDA
All connected via a breadboard.
However, regardless of what example code I use, none of it detects the sensor. Nor does I2C_scanner. I did have to solder the header pins myself, which was my first solder job ever, but it looks pretty good to my untrained eye. Could it be that the sensor is simply faulty?
Could it be that the sensor is simply faulty?
With cheap Chinese boards you never know if it's a fake chip.
Unfortunately your vendor doesn't supply schematics of the board, so you have to find them out yourself. On the photos it looks like this board is designed to be used by a 5V MCU, so this might be a problem but that's a lot of guessing.
1. The pictorial view of BME280 Sensor. At the other side of the sensor, there are electronics of which one item is the 5/3.3V regulator.
2. The schematic of BME280 of Step-1.
3. I have the following sketch that works well between my NodeMCU and BME280.
#include <Wire.h>
#include "BlueDot_BME280.h"
BlueDot_BME280 bme280 = BlueDot_BME280();
void setup()
{
Serial.begin(115200);
Wire.begin(4, 5); //sda scl
bme280.parameter.communication = 0; //Choose communication protocol
bme280.parameter.I2CAddress = 0x76; //Choose I2C Address
bme280.parameter.sensorMode = 0b11; //Choose sensor mode
bme280.parameter.IIRfilter = 0b100; //Setup for IIR Filter
bme280.parameter.tempOversampling = 0b101; //Setup Temperature Ovesampling
bme280.parameter.tempOutsideCelsius = 15; //default value of 15°C
bme280.init();
}
void loop()
{
Serial.print("Temperature in Celsius:\t\t");
Serial.println(bme280.readTempC());
delay(2000);
}
I no longer have the code for the ESP32
I used this code, from a DUE, using the uMT library and ported over to a ESP32, freeRTOS, for the BMP280:
#include <Wire.h>
#define BMP085_ADDRESS 0x77 // I2C address of BMP085
#define BMP_Interval 65503
const unsigned char OSS = 0; // Oversampling Setting
// Calibration values
int ac1;
int ac2;
int ac3;
unsigned int ac4;
unsigned int ac5;
unsigned int ac6;
int b1;
int b2;
int mb;
int mc;
int md;
// b5 is calculated in bmp085GetTemperature(...), this variable is also used in bmp085GetPressure(...)
// so ...Temperature(...) must be called before ...Pressure(...).
long b5;
//******************************************
// bmp085 functions
//******************************************
// Calculate pressure given up
// calibration values must be known
// b5 is also required so bmp085GetTemperature(...) must be called first.
// Value returned will be pressure in units of Pa.
long bmp085GetPressure(unsigned long up)
{
long x1, x2, x3, b3, b6, p;
unsigned long b4, b7;
b6 = b5 - 4000;
// Calculate B3
x1 = (b2 * (b6 * b6) >> 12) >> 11;
x2 = (ac2 * b6) >> 11;
x3 = x1 + x2;
b3 = (((((long)ac1) * 4 + x3) << OSS) + 2) >> 2;
// Calculate B4
x1 = (ac3 * b6) >> 13;
x2 = (b1 * ((b6 * b6) >> 12)) >> 16;
x3 = ((x1 + x2) + 2) >> 2;
b4 = (ac4 * (unsigned long)(x3 + 32768)) >> 15;
b7 = ((unsigned long)(up - b3) * (50000 >> OSS));
if (b7 < 0x80000000)
p = (b7 << 1) / b4;
else
p = (b7 / b4) << 1;
x1 = (p >> 8) * (p >> 8);
x1 = (x1 * 3038) >> 16;
x2 = (-7357 * p) >> 16;
p += (x1 + x2 + 3791) >> 4;
return p;
}
// Calculate temperature given ut.
// Value returned will be in units of 0.1 deg C
short bmp085GetTemperature(unsigned int ut)
{
long x1, x2;
x1 = (((long)ut - (long)ac6) * (long)ac5) >> 15;
x2 = ((long)mc << 11) / (x1 + md);
b5 = x1 + x2;
return ((b5 + 8) >> 4);
}
// Read the uncompensated pressure value
unsigned long bmp085ReadUP()
{
unsigned char msb, lsb, xlsb;
unsigned long up = 0;
// Write 0x34+(OSS<<6) into register 0xF4
// Request a pressure reading w/ oversampling setting
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF4);
Wire.write(0x4 + (OSS << 6));
Wire.endTransmission();
// Wait for conversion, delay time dependent on OSS
// delay(2 + (3 << OSS));
Kernel.Tm_WakeupAfter( 2 + (3 << OSS) );
// Read register 0xF6 (MSB), 0xF7 (LSB), and 0xF8 (XLSB)
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF6);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 3);
// Wait for data to become available
while (Wire.available() < 3)
;
msb = Wire.read();
lsb = Wire.read();
xlsb = Wire.read();
up = (((unsigned long) msb << 16) | ((unsigned long) lsb << 8) | (unsigned long) xlsb) >> (8 - OSS);
return up;
}
// Read the uncompensated temperature value
unsigned int bmp085ReadUT()
{
unsigned int ut;
// Write 0x2E into Register 0xF4
// This requests a temperature reading
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(0xF4);
Wire.write(0x2E);
Wire.endTransmission();
// Wait at least 4.5ms
Kernel.Tm_WakeupAfter( 5 );
// delay(5);
// Read two bytes from registers 0xF6 and 0xF7
ut = bmp085ReadInt(0xF6);
return ut;
}
// Stores all of the bmp085's calibration values into global variables
// Calibration values are required to calculate temp and pressure
// This function should be called at the beginning of the program
void bmp085Calibration()
{
ac1 = bmp085ReadInt(0xAA);
ac2 = bmp085ReadInt(0xAC);
ac3 = bmp085ReadInt(0xAE);
ac4 = bmp085ReadInt(0xB0);
ac5 = bmp085ReadInt(0xB2);
ac5 = bmp085ReadInt(0xB2);
ac6 = bmp085ReadInt(0xB4);
b1 = bmp085ReadInt(0xB6);
b2 = bmp085ReadInt(0xB8);
mb = bmp085ReadInt(0xBA);
mc = bmp085ReadInt(0xBC);
md = bmp085ReadInt(0xBE);
}
// Read 2 bytes from the BMP085
// First byte will be from 'address'
// Second byte will be from 'address'+1
int bmp085ReadInt(unsigned char address)
{
unsigned char msb, lsb;
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 2);
while (Wire.available() < 2);
msb = Wire.read();
lsb = Wire.read();
return (int) msb << 8 | lsb;
}
// Read 1 byte from the BMP085 at 'address'
char bmp085Read(unsigned char address)
{
unsigned char data;
Wire.beginTransmission(BMP085_ADDRESS);
Wire.write(address);
Wire.endTransmission();
Wire.requestFrom(BMP085_ADDRESS, 1);
while (!Wire.available())
;
return Wire.read();
}
void fCheck_Pressure()
{
Errno_t error;
// TimerId_t TmId;
String sMsgToSend;
sMsgToSend.reserve( StringBufferSize );
short bmp_temperature;
long bmp_pressure;
// float bmp_altitude;
//Serial.println( "do fCheck_Pressure" );
//Serial.flush();
while (1)
{
error = Kernel.Tm_WakeupAfter( BMP_Interval ); // Wake up after ... seconds
if (error != E_SUCCESS)
{
Serial.print(F(" WakeupAfter(): Tm_WakeupAfter() Failure! - returned "));
Serial.print((unsigned)error);
Serial.flush();
break;
}
if ( digitalReadDirect( MWM_PINin ) == 0 )
{
sMsgToSend = "Pa ";
// Serial.println( "do fCheck_Pressure3" );
// Serial.flush();
bmp_temperature = bmp085GetTemperature(bmp085ReadUT());
bmp_pressure = bmp085GetPressure(bmp085ReadUP());
// sMsgToSend.concat( String(bmp_temperature) + sSeperator );
sMsgToSend.concat( String(bmp_pressure) + sSeperator );
// sMsgToSend.concat( String(bmp_altitude) + sSeperator );
// Serial.println( sMsgToSend );
// Serial.flush();
Kernel.Sm_Claim(SEM_ID_01, uMT_WAIT); // // claim a single SEMAPHORE token
sMessageToSend = sMsgToSend;
Kernel.Ev_Send(iEvtID_F, EVENT_F); // trigger fSendOut_SEMAPHORE + consume a single SEMAPHORE token
sMsgToSend = "";
}
}
// // bTask2Started = false;
}
//******************************************
void fCheck_TH()
{
// TimerId_t TmId1;
String sMsgToSend;
byte temperature = 0;
byte humidity = 0;
String sTH = "TH ";
sMsgToSend.reserve( 16 );
while (1)
{
Kernel.Tm_WakeupAfter( iDHT_Interval ); // Wake up after ... seconds
if ( digitalReadDirect( MWM_PINin ) == 0 )
{
dht11.read(&temperature, &humidity, NULL);
sMsgToSend = sTH;
sMsgToSend.concat( String(temperature) + sSeperator + String(humidity) );
// Serial.println( sMsgToSend );
// Serial.flush();
Kernel.Sm_Claim(SEM_ID_01, uMT_WAIT); // // claim a single SEMAPHORE token
sMessageToSend = sMsgToSend;
Kernel.Ev_Send(iEvtID_F, EVENT_F); // trigger fSendOut_SEMAPHORE + consume a single SEMAPHORE token
sMsgToSend = "";
}
} // while (1)
}
You'll have to edit out the uMT stuff such as Kernel.Tm_WakeupAfter( 5 ); and change that to either delay or, if you are using freeRTOS to vTaskDelay( pdMS_TO_TICKS( 5 ) );. The libraries for the device just plain did not work for the DUE or the ESP32. If I remember correctly I had to use pull up resistors of 2.2K.
I have switched to the SPI version of the device. The #include <Adafruit_BMP280.h> works well for trhe ESP32.
The SPI version with a ESP32 and freeRETOS
#include <Adafruit_BMP280.h>
#include <SPI.h>
#include "esp_system.h" //This inclusion configures the peripherals in the ESP system.
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/timers.h"
#include "freertos/event_groups.h"
#define DoPressureDataCollectionEvent ( 1 << 7 ) //10000000
#define DEVICE_PIN 5
// BME_SCK 18 // keep for reference info
// BME_MISO 19
// BME_MOSI 23
Adafruit_BMP280 bme(DEVICE_PIN); // hardware SPI
// Adafruit_BMP280 bme(DEVICE_PIN, BME_MOSI, BME_MISO, BME_SCK); // keep for reference
QueueHandle_t xQ_PressureMessage;
struct stuPressureMessage
{
float BMEpressure = 0.0;
float BMEtemperature = 0.0;
} xPressureMessage;
// float BMEpressure = 0.0;
// float BMEtemperature = 0.0;
void setup()
{
////
// Wire.setClock( 100000 );
Wire.setClock( 2000000 ); // shoud use pullups
//Wire.setClock( 3400000 ); // shoud use pullups
Serial.begin( SerialDataBits );
while (!bme.begin())
{
Serial.println("Could not find BME280 sensor!");
vTaskDelay( pdMS_TO_TICKS( OneK ) );
}
//
eg = xEventGroupCreate();
xQ_PressureMessage = xQueueCreate( 1, sizeof(struct stuPressureMessage*) ); // sends a queue pointer to the structure
xTaskCreatePinnedToCore( fCheck_Pressure, "fCheck_Pressure", TaskStack10K1, NULL, Priority3, NULL, TaskCore1 ); //assigned to core 1
sema_CheckPressure = xSemaphoreCreateMutex(); // create Semaphore
xSemaphoreGive( sema_CheckPressure );
} //void setup()
void loop() {} // runs on core 1
//
void fCheck_Pressure( void * parameter )
{
struct stuPressureMessage *pxMessage;
while (1)
{
xEventGroupWaitBits (eg, PressureEvent, pdTRUE, pdTRUE, portMAX_DELAY) ;
if ( xSemaphoreTake( sema_CheckPressure, xSemaphoreTicksToWait ) == pdTRUE )
{
xPressureMessage.BMEtemperature = bme.readTemperature();
xPressureMessage.BMEpressure = bme.readPressure() / 133.3223684; // mmHg
if ( xSemaphoreTake(sema_PressureDataCollection, xSemaphoreTicksToWait ) == pdTRUE )
{
xPressureData.BMEpressure = int( xPressureMessage.BMEpressure ); // transfer pressure reading into xPressureData.BMEpressure
xSemaphoreGive( sema_PressureDataCollection );
}
pxMessage = &xPressureMessage;
xQueueOverwrite( xQ_PressureMessage, (void *) &pxMessage ); // sends a copy of the structure in the queue
xEventGroupSetBits( eg, DoPressureDataCollectionEvent ); // trigger fDoPressureDataCollection
xSemaphoreGive( sema_CheckPressure );
}
// Serial.print( "fCheck_Pressure " );
// Serial.print(uxTaskGetStackHighWaterMark( NULL ));
// Serial.println();
// Serial.flush();
}
vTaskDelete( NULL );
} // void fCheck_Pressure( void * parameter )
The schematic of BME280 of Step-1.
I'm quite sure this isn't correct. Take a look at the connector CON4. In the schematics it's pinout is VIN, SCL, SDA, GND while on the picture it's VIN, GND, SCL, SDA. So please allow that I doubt that the rest of the schematics is correct.
pylon:
I'm quite sure this isn't correct. Take a look at the connector CON4. In the schematics it's pinout is VIN, SCL, SDA, GND while on the picture it's VIN, GND, SCL, SDA. So please allow that I doubt that the rest of the schematics is correct.
If you own a BME280 Module, please look at both sides of the Module and observe that the electronics components do match with the schematics at 'similarity' level. Moreover, the connector pins of the BME280 Board are not marked as 1, 2, 3, and 4.
Moreover, the connector pins of the BME280 Board are not marked as 1, 2, 3, and 4.
Schematics that has a different connector order than the connector in reality are extremely dangerous if not to say useless. My opinion.
pylon:
Schematics that has a different connector order than the connector in reality are extremely dangerous if not to say useless. My opinion.
In many occasions, we need to work in hazardous environment; but, we are (for most of the times) safe as we are aware that there could happen an accident.
In many occasions, we need to work in hazardous environment; but, we are (for most of the times) safe as we are aware that there could happen an accident.
In my country you get legal problems if you're working in a hazardous environment without special protection and especially if the document is not correct. The least problem you get is loosing the assurance protection.
pylon:
In my country you get legal problems if you're working in a hazardous environment without special protection and especially if the document is not correct. The least problem you get is loosing the assurance protection.
K+.