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register settings for BMP280

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abimann

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Hello , cannot connect my FPGA to BMP280 ,, code has not problem can read some data from BMP but pressure doesnot change

HTML: 
 write operation 
"1110110"&"0"&"11100000"&"10110110";--softreset _ B6
"1110110"&"0"&"11110100"&"10010011";--F4,Temp oversampling x8,Press osrsP oversampling x8, normal mode 
"1110110"&"0"&"11110101"&"01101100";--F5 125, filter 8  disable SPI
read operation:
        BME280_REGISTER_PRESSUREDATA       = 0xF7,
        BME280_REGISTER_TEMPDATA           = 0xFA,
        BME280_REGISTER_HUMIDDATA          = 0xFD

no data change from :

BME280_REGISTER_PRESSUREDATA = 0xF7,
BME280_REGISTER_TEMPDATA = 0xFA,
BME280_REGISTER_HUMIDDATA = 0xFD
Somebody can help me ?
 

abimann said:
Hello , cannot connect my FPGA to BMP280 ,, code has not problem can read some data from BMP but pressure doesnot change

HTML: 
 write operation 
"1110110"&"0"&"11100000"&"10110110";--softreset _ B6
"1110110"&"0"&"11110100"&"10010011";--F4,Temp oversampling x8,Press osrsP oversampling x8, normal mode 
"1110110"&"0"&"11110101"&"01101100";--F5 125, filter 8  disable SPI
read operation:
        BME280_REGISTER_PRESSUREDATA       = 0xF7,
        BME280_REGISTER_TEMPDATA           = 0xFA,
        BME280_REGISTER_HUMIDDATA          = 0xFD

no data change from :

BME280_REGISTER_PRESSUREDATA = 0xF7,
BME280_REGISTER_TEMPDATA = 0xFA,
BME280_REGISTER_HUMIDDATA = 0xFD
Somebody can help me ?
Click to expand...

Hello,

maybe it be helpful:

https://github.com/adafruit/Adafruit_BMP280_Library/blob/master/Adafruit_BMP280.cpp

At this link is Arduino library for that sensor, and here is a method which is reading pressure - it is quite complex:

Code: 
float Adafruit_BMP280::readPressure(void) {
  int64_t var1, var2, p;

  // Must be done first to get the t_fine variable set up
  readTemperature();

  int32_t adc_P = read24(BMP280_REGISTER_PRESSUREDATA);
  adc_P >>= 4;

  var1 = ((int64_t)t_fine) - 128000;
  var2 = var1 * var1 * (int64_t)_bmp280_calib.dig_P6;
  var2 = var2 + ((var1*(int64_t)_bmp280_calib.dig_P5)<<17);
  var2 = var2 + (((int64_t)_bmp280_calib.dig_P4)<<35);
  var1 = ((var1 * var1 * (int64_t)_bmp280_calib.dig_P3)>>8) +
    ((var1 * (int64_t)_bmp280_calib.dig_P2)<<12);
  var1 = (((((int64_t)1)<<47)+var1))*((int64_t)_bmp280_calib.dig_P1)>>33;

  if (var1 == 0) {
    return 0;  // avoid exception caused by division by zero
  }
  p = 1048576 - adc_P;
  p = (((p<<31) - var2)*3125) / var1;
  var1 = (((int64_t)_bmp280_calib.dig_P9) * (p>>13) * (p>>13)) >> 25;
  var2 = (((int64_t)_bmp280_calib.dig_P8) * p) >> 19;

  p = ((p + var1 + var2) >> 8) + (((int64_t)_bmp280_calib.dig_P7)<<4);
  return (float)p/256;
}

The register address of BMP280_REGISTER_PRESSUREDATA is proper in your code. Maybe analysis of source code of this library can help you.

Regards
 

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