I'm using a CYBLE-222014-01 module and I downloaded a driver from ST Micro for their LIS3DH accelerometer (which according to ST is the same register ...
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I'm using a CYBLE-222014-01 module and I downloaded a driver from ST Micro for their LIS3DH accelerometer (which according to ST is the same register set as LIS2DH which I am using).
In their code, ST provide 2 places where you have to build your own functions (they give 2 comment lines giving very basic suggestions) and I've written code that compiles but I'm looking for a check of understanding - note I'm hard-controlling the chip select (CS) line. Here's teh code ...
const uint8 READ = 0b10000000; // LIS2DH's read mask
const uint8 WRITE = 0b00111111; // LIS2DH's write mask
uint8 dataToSend;
u8_t LIS3DH_ReadReg(u8_t Reg, u8_t* Data) {
//To be completed with either I2c or SPI reading function
//i.e. *Data = SPI_Mems_Read_Reg( Reg );
// my code starts here
// combine the R/W register address and the command into one uint8
dataToSend = (Reg | READ);
ACC_CS_Write(0); // clear ACC_CS for access
SPI_SpiUartWriteTxData(dataToSend); // TM
*Data = SPI_SpiUartReadRxData(); // TM read data from the received buffer
ACC_CS_Write(1); // set ACC_CS
return 1;
}
/*******************************************************************************
* Function Name : LIS3DH_WriteReg
* Description : Generic Writing function. It must be fullfilled with either
* : I2C or SPI writing function
* Input : Register Address, Data to be written
* Output : None
* Return : None
*******************************************************************************/
u8_t LIS3DH_WriteReg(u8_t WriteAddr, u8_t Data) {
//To be completed with either I2c or SPI writing function
//i.e. SPI_Mems_Write_Reg(WriteAddr, Data);
dataToSend = (WriteAddr & WRITE); // TM set up write mask (NB the M/S bit is also 0 for single address
ACC_CS_Write(0); // clear ACC_CS for access TM ???? do we want to clear other CS or use a SPI busy flag ???
SPI_SpiUartWriteTxData(dataToSend); // TM send mask+address
SPI_SpiUartWriteTxData(Data); // TM send actual data to write
ACC_CS_Write(1); // set ACC_CS
return 1;
}
The bit that's confusing me is that the data sheet for the LIS2DH device indicates that for an SPI read, the register address is sent to the device and then the contents are returns in the next 8 bits, so for my LIS3DH_ReadReg() function, won't I need to throw away the first Bte I get back with the SPI_SpiUartReadRxData() function?
or maybe someone's trodden this path before and already has code they are willing to share?
Thanks in advance for any help.
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