/**
* @brief Select the bandwidth the digital filter pass allows.
* @return 0 if successful, -1 if not
* @param rate[in] Bandwidth setting to be used
*
* EEPROM must be write-enabled before calling this function.
*/
static int32_t PIOS_BMA180_SelectBW(enum bma180_bandwidth bw)
{
if(PIOS_BMA180_Validate(dev) != 0)
return -1;
dev->bandwidth = bw;
uint8_t reg;
reg = PIOS_BMA180_GetReg(BMA_BW_ADDR);
reg = (reg & ~BMA_BW_MASK) | ((bw << BMA_BW_SHIFT) & BMA_BW_MASK);
return PIOS_BMA180_SetReg(BMA_BW_ADDR, reg);
}
/**
* @brief Claim the SPI bus for the accel communications and select this chip
* \param[in] pointer which receives if a task has been woken
* @return 0 if successful, -1 if unable to claim bus
*/
int32_t PIOS_BMA180_ClaimBusISR(bool *woken)
{
if(PIOS_BMA180_Validate(dev) != 0)
return -1;
if(PIOS_SPI_ClaimBusISR(dev->spi_id, woken) != 0) {
return -1;
}
PIOS_SPI_RC_PinSet(dev->spi_id,dev->slave_num,0);
return 0;
}
/**
* @brief Read a register from BMA180
* @returns The register value or -1 if failure to get bus
* @param reg[in] Register address to be read
*/
int32_t PIOS_BMA180_GetReg(uint8_t reg)
{
if(PIOS_BMA180_Validate(dev) != 0)
return -1;
uint8_t data;
if(PIOS_BMA180_ClaimBus() != 0)
return -1;
PIOS_SPI_TransferByte(dev->spi_id,(0x80 | reg) ); // request byte
data = PIOS_SPI_TransferByte(dev->spi_id,0 ); // receive response
PIOS_BMA180_ReleaseBus();
return data;
}
/**
* @brief Returns the scale the BMA180 chip is using
* @return Scale (m / s^2) / LSB
*/
float PIOS_BMA180_GetScale()
{
if(PIOS_BMA180_Validate(dev) != 0)
return -1;
switch (dev->cfg->range) {
case BMA_RANGE_1G:
return GRAVITY / 8192.0f;
case BMA_RANGE_1_5G:
return GRAVITY / 5460.0f;
case BMA_RANGE_2G:
return GRAVITY / 4096.0f;
case BMA_RANGE_3G:
return GRAVITY / 2730.0f;
case BMA_RANGE_4G:
return GRAVITY / 2048.0f;
case BMA_RANGE_8G:
return GRAVITY / 1024.0f;
case BMA_RANGE_16G:
return GRAVITY / 512.0f;
}
return 0;
}
