bmp581.c

/***********************************************************************************
 * @file        BMP581.c                                                           *
 * @author      Matt Ricci                                                         *
 * @addtogroup  BMP581                                                             *
 *                                                                                 *
 * @todo Add altitude calculation method                                           *
 * @todo Document implementation                                                   *
 * @todo Move private interface methods (read/write register) to static functions  *
 *       with internal prototypes.                                                 *
 * @todo Replace giga loops with hardware timer                                    *
 * @{                                                                              *
 ***********************************************************************************/
 
#include "bmp581.h"
 
/* =============================================================================== */
BMP581_t BMP581_init(
    BMP581_t *baro,
    SPI_t *spi,
    GPIOpin_t cs,
    float tempSensitivity,
    float pressSensitivity
) {
  baro->base             = spi;
  baro->cs               = cs;
  baro->tempSensitivity  = tempSensitivity;
  baro->pressSensitivity = pressSensitivity;
  baro->update           = BMP581_update;
  baro->readTemp         = BMP581_readTemp;
  baro->readRawTemp      = BMP581_readRawTemp;
  baro->processRawTemp   = BMP581_processRawTemp;
  baro->readPress        = BMP581_readPress;
  baro->readRawPress     = BMP581_readRawPress;
  baro->processRawPress  = BMP581_processRawPress;
 
  // Initial dummy read
  BMP581_readRegister(baro, 0x01);
 
  // Soft reset device
  BMP581_writeRegister(baro, BMP581_CMD, 0xB6);
 
  while (BMP581_readRegister(baro, BMP581_CHIP_ID) == 0x00);                                           // Check chip ID
  while (BMP581_readRegister(baro, BMP581_INT_STATUS) != 0x10);                                        // Wait for POR complete
  while (!(BMP581_readRegister(baro, BMP581_STATUS) & BMP581_STATUS_NVM_RDY));                         // Check device status NVM ready
  while ((BMP581_readRegister(baro, BMP581_STATUS) & BMP581_STATUS_NVM_ERR));                          // Check device status NVM err
 
  BMP581_writeRegister(baro, BMP581_ODR_CFG, BMP581_ODR_CFG_DEEP_DIS);                                 // Disable deep sleep
  for (uint32_t i = 0; i < 0x1FFFF; i++);                                                              // Wait for at least t_standby
  BMP581_writeRegister(baro, BMP581_ODR_CFG, BMP581_ODR_CFG_DEEP_DIS | BMP581_ODR_CFG_PWR_CONTINUOUS); // Set continuous sample
 
  // Read OSR config for reserved bits and enable pressure measurement with 16x oversampling
  uint8_t OSRCFG = BMP581_readRegister(baro, BMP581_OSR_CFG);
  BMP581_writeRegister(baro, BMP581_OSR_CFG, (BMP581_OSR_CFG_RESERVED & OSRCFG) | BMP581_OSR_CFG_PRESS_EN | BMP581_OSR_CFG_OSR_P_16);
 
  // Set ground pressure reading on init
  for (uint32_t i = 0; i < 0x1FFFF; i++);    // Wait for at least t_reconf
  baro->readPress(baro, &baro->groundPress); // Read current pressure
 
  return *baro;
}
 
/******************************** DEVICE METHODS ********************************/
 
/* =============================================================================== */
void BMP581_update(BMP581_t *baro) {
  baro->readRawTemp(baro, baro->rawTemp);
  baro->processRawTemp(baro, baro->rawTemp, &baro->temp);
 
  baro->readRawPress(baro, baro->rawPress);
  baro->processRawPress(baro, baro->rawPress, &baro->press);
}
 
/* =============================================================================== */
void BMP581_readTemp(BMP581_t *baro, float *out) {
  uint8_t bytes[BMP581_DATA_TOTAL];
  baro->readRawTemp(baro, bytes);
  baro->processRawTemp(baro, bytes, out);
}
 
/* =============================================================================== */
void BMP581_processRawTemp(BMP581_t *baro, uint8_t *bytes, float *out) {
  *out = baro->tempSensitivity * (int32_t)(((uint32_t)bytes[0] << 16) | ((uint32_t)bytes[1] << 8) | bytes[0]);
}
 
/* =============================================================================== */
void BMP581_readRawTemp(BMP581_t *baro, uint8_t *out) {
  out[0] = BMP581_readRegister(baro, BMP581_TEMPERATURE_MSB);  // temp high
  out[1] = BMP581_readRegister(baro, BMP581_TEMPERATURE_LSB);  // temp low
  out[2] = BMP581_readRegister(baro, BMP581_TEMPERATURE_XLSB); // temp mid
}
 
/* =============================================================================== */
void BMP581_readPress(BMP581_t *baro, float *out) {
  uint8_t bytes[BMP581_DATA_TOTAL];
  baro->readRawPress(baro, bytes);
  baro->processRawPress(baro, bytes, out);
}
 
/* =============================================================================== */
void BMP581_processRawPress(BMP581_t *baro, uint8_t *bytes, float *out) {
  *out = baro->pressSensitivity * (int32_t)(((uint32_t)bytes[0] << 16) | ((uint32_t)bytes[1] << 8) | bytes[0]);
}
 
/* =============================================================================== */
void BMP581_readRawPress(BMP581_t *baro, uint8_t *out) {
  uint8_t tmp[BMP581_DATA_SIZE];
  BMP581_readRegisters(baro, BMP581_PRESSURE_XLSB, BMP581_DATA_SIZE, tmp);
  out[0] = tmp[2]; // temp high
  out[1] = tmp[1]; // temp low
  out[2] = tmp[0]; // temp mid
}
 
/******************************** INTERFACE METHODS ********************************/
 
void BMP581_writeRegister(BMP581_t *baro, uint8_t address, uint8_t data) {
  SPI_t *spi   = baro->base;
  GPIOpin_t cs = baro->cs;
 
  cs.reset(&cs);
 
  // Send read command and address
  uint8_t payload = address & 0x7F; // Load payload with address and read command
  spi->transmit(spi, payload);      // Transmit payload
  spi->transmit(spi, data);         // Transmit dummy data and read response data
 
  cs.set(&cs);
}
 
uint8_t BMP581_readRegister(BMP581_t *baro, uint8_t address) {
  uint8_t response = 0;
  SPI_t *spi       = baro->base;
  GPIOpin_t cs     = baro->cs;
 
  cs.reset(&cs);
 
  // Send read command and address
  uint8_t payload = address | 0x80;              // Load payload with address and read command
  response        = spi->transmit(spi, payload); // Transmit payload
  response        = spi->transmit(spi, 0xFF);    // Transmit dummy data and read response data
 
  cs.set(&cs);
 
  return response;
}
 
void BMP581_readRegisters(BMP581_t *baro, uint8_t address, uint8_t count, uint8_t *out) {
  SPI_t *spi   = baro->base;
  GPIOpin_t cs = baro->cs;
 
  cs.reset(&cs);
 
  // Send read command and address
  uint8_t payload = address | 0x80; // Load payload with address and read command
  spi->transmit(spi, payload);      // Transmit payload
 
  // Auto increment read through registers
  for (uint8_t i = 0; i < count; i++) {
    out[i] = spi->transmit(spi, 0xFF);
  }
 
  cs.set(&cs);
}