1.8.7.55 1.25.6.55 1.26.5.55 1.27.5.55 1.28.6.55 1.36.7.53 1.41.5.55 1.42.3.55 FLEXCOMx_TWI_WriteRead Function
C
/* x = FLEXCOM instance number */
/* TWI master mode */
bool FLEXCOMx_TWI_WriteRead(uint16_t address, uint8_t *wdata, size_t wlength, uint8_t *rdata, size_t rlength)
Summary
Write and read data from TWI slave
Description
This function writes data from the wdata buffer to the slave of the given address and then reads data from the slave and stores the received data in the rdata. The function generates a Start condition on the bus and will then send wlength number of bytes contained in wdata buffer. The function will then insert a Repeated start condition and proceed to read rlength number of bytes from the slave. The received bytes are stored in rdata buffer. A Stop condition is generated after the last byte has been received. If the slave NAKs the request or a bus error was encountered on the bus, the transfer is terminated. The application can call FLEXCOMx_TWI_ErrorGet function to know the cause of the error. The function is non-blocking. It initiates the bus activity and returns immediately. The transfer is then completed in the peripheral interrupt. A transfer request cannot be placed when another transfer is in progress. Calling this function when another function is already in progress will cause the function to return false. The library will call the registered callback function when the transfer has completed.
Precondition
FLEXCOMx_TWI_Initialize must have been called for the associated FLEXCOM TWI instance.
Parameters
| Param | Description |
|---|---|
| address | 7-bit / 10-bit slave address |
| wdata | pointer to write data buffer |
| wlength | write data length in bytes |
| rdata | pointer to read data buffer |
| rlength | read data length in bytes |
Returns
true - The request was placed successfully and the bus activity was initiated
false - The request fails, if there was already a transfer in progress when this function was called.
Example
uint8_t myTxData [NUM_BYTES] = {'1', '0', ' ', 'B', 'Y', 'T', 'E', 'S'};
uint8_t myRxData [NUM_BYTES] = {0};
if(!FLEXCOM0_TWI_WriteRead( SLAVE_ADDR, &myTxData[0], NUM_BYTES, myRxData, NUM_BYTES ))
{
// error handling
}
Remarks
Calling this function is not the same as calling the FLEXCOMx_TWI_Write() function and then calling the FLEXCOMx_TWI_Read() function. The FLEXCOMx_TWI_WriteRead function will insert a Repeated Start condition between the Write and the Read stages. The FLEXCOMx_TWI_Write() and the FLEXCOMx_TWI_Read() function generates a stop condition after the write and the read has completed.