U2C_RESULT U2C_SpiReadSS(
HANDLE hDevice,
BYTE* pInBuffer,
WORD Length
ULONG IoNumber
BOOL ActiveHigh
);
The U2C_SpiReadSS() function shifts in (reads) a stream of up to 256 bytes from the SPI slave device.
In contrast to U2C_SpiRead() function, U2C_SpiReadSS() also selects the SPI slave device to communicate with. Slave Select pin should be preconfigured withU2C_SpiConfigSS() function. You can configure any number of pins for Slave Select signal and specify different pins for each SPI transaction.
Use U2C_SpiRead() function if you don't want to involve slave device selection into SPI transaction. This can be useful if you want to receive several buffers through SPI Bus changing Slave Select pin only once. You can use GPIO routines to work with Slave Select pin in such a case.
Parameters:
- hDevice
Handle to the U2C-12 device.
- pInBuffer
Pointer to the buffer that receives the data shifted in from the SPI slave device.
- Length
Number of bytes to be shifted in. Maximum value is 256.
- IoNumber
GPIO pin to be used for SPI slave device selection.
- Numbers 0..7 correspond to Port A pins 0..7
- Numbers 8..15 correspond to Port B pins 0..7
- Number 16..23 correspond to Port C pins 0..7
- ActiveHigh
This parameter determines the active state of the Slave Select pin (state during the SPI transfer). If ActiveHigh is TRUE - Slave Select pin value will be changed from logical "0" to logical "1" before SPI transaction and returned back to logical "0" after the data is transmitted. If ActiveHigh is FALSE - Slave Select pin value will be changed from logical "1" to logical "0" before SPI transaction and returned back to logical "1" after the data is transmitted.
Return values:
U2C_SUCCESS
The data was successfully read.
U2C_HARDWARE_NOT_FOUND
U2C-12 device referenced by hDevice handle was not found.
U2C_BAD_PARAMETER
Length or IoNumber parameter is out of range.