CC3220SF: How many bytes of data can be received as a SPI slave?

Howdy Cherry,

I am going to be answering the following questions from this code. Just to make sure were on the same page.

// SPI already opened in callback mode
SPI_Transaction t0, t1, t2;
t0.txBuf = txBuff0;
t0.rxBuf = rxBuff0;
t0.count = 2000;
t1.txBuf = txBuff1;
t1.rxBuf = rxBuff1;
t1.count = 1000;
t2.txBuf = txBuff2;
t2.rxBuf = NULL;
t2.count = 1000;
bool transferOk = false;
if (SPI_transfer(spiHandle, &t0)) {
    if (SPI_transfer(spiHandle, &t1)) {
            transferOk = SPI_transfer(spiHandle, &t2);
        }
    }
}

In this code 3 instances of the struct SPI_Transactions are created t0, t1, and t2. Each struct has the following variables. Link

size_t 	count
 
void * 	txBuf
 
void * 	rxBuf
 
void * 	arg
 
SPI_Status 	status
 
void * 	nextPtr

1.)  t0.count is set to 2000. This means that SPI_Transfer(spiHandle, &t0) will not return a 1 or complete until 2000 frames were transferred. The amount of bytes transferred ultimately depend on the Frame size of the buffer so 8, 16, or 32 bit. 

2.) txBuff1, 2 ,3 are all separate buffers in their own place in memory which have been assigned to each respective tx.buff variable.

I hope this helps,

Rogelio