/*!
* @brief Initiate (start) a transfer. This is not a public API as it is called from other
* driver functions
*/
static spi_status_t SPI_DRV_MasterStartTransfer(uint32_t instance,
const spi_master_user_config_t * device)
{
/* instantiate local variable of type spi_master_state_t and point to global state */
spi_master_state_t * spiState = (spi_master_state_t *)g_spiStatePtr[instance];
uint32_t calculatedBaudRate;
SPI_Type *base = g_spiBase[instance];
/* Check that we're not busy.*/
if (spiState->isTransferInProgress)
{
return kStatus_SPI_Busy;
}
/* Configure bus for this device. If NULL is passed, we assume the caller has
* preconfigured the bus using SPI_DRV_MasterConfigureBus().
* Do nothing for calculatedBaudRate. If the user wants to know the calculatedBaudRate
* then they can call this function separately.
*/
if (device)
{
SPI_DRV_MasterConfigureBus(instance, device, &calculatedBaudRate);
}
/* In order to flush any remaining data in the shift register, disable then enable the SPI */
SPI_HAL_Disable(base);
SPI_HAL_Enable(base);
#if FSL_FEATURE_SPI_16BIT_TRANSFERS
spi_data_bitcount_mode_t bitCount;
bitCount = SPI_HAL_Get8or16BitMode(base);
/* Check the transfer byte count. If bits/frame > 8, meaning 2 bytes if bits/frame > 8, and if
* the transfer byte count is an odd count we'll have to increase the transfer byte count
* by one and assert a flag to indicate to the receive function that it will need to handle
* an extra byte so that it does not inadverently over-write an another byte to the receive
* buffer. For sending the extra byte, we don't care if we read past the send buffer since we
* are only reading from it and the absolute last byte (that completes the final 16-bit word)
* is a don't care byte anyway.
*/
if ((bitCount == kSpi16BitMode) && (spiState->remainingSendByteCount & 1UL))
{
spiState->remainingSendByteCount += 1;
spiState->remainingReceiveByteCount += 1;
spiState->extraByte = true;
}
else
{
spiState->extraByte = false;
}
#endif
/* If the byte count is zero, then return immediately.*/
if (spiState->remainingSendByteCount == 0)
{
SPI_DRV_MasterCompleteTransfer(instance);
return kStatus_SPI_Success;
}
/* Save information about the transfer for use by the ISR.*/
spiState->isTransferInProgress = true;
spiState->transferredByteCount = 0;
/* Make sure TX data register (or FIFO) is empty. If not, return appropriate
* error status. This also causes a read of the status
* register which is required before writing to the data register below.
*/
if (SPI_HAL_IsTxBuffEmptyPending(base) != 1)
{
return kStatus_SPI_TxBufferNotEmpty;
}
#if FSL_FEATURE_SPI_16BIT_TRANSFERS
/* If the module/instance contains a FIFO (and if enabled), proceed with FIFO usage for either
* 8- or 16-bit transfers, else bypass to non-FIFO usage.
*/
if ((g_spiFifoSize[instance] != 0) && (SPI_HAL_GetFifoCmd(base)))
{
/* First fill the FIFO with data */
SPI_DRV_MasterFillupTxFifo(instance);
/* If the remaining RX byte count is less than the RX FIFO watermark, enable
* the TX FIFO empty interrupt. Once the TX FIFO is empty, we are ensured
* that the transmission is complete and can then drain the RX FIFO.
* Else, enable the RX FIFO interrupt based on the watermark. In the IRQ
* handler, another check will be made to see if the remaining RX byte count
* is less than the RX FIFO watermark.
*/
if (spiState->remainingReceiveByteCount < g_spiFifoSize[instance])
{
SPI_HAL_SetIntMode(base, kSpiTxEmptyInt, true); /* TX FIFO empty interrupt */
}
else
{
SPI_HAL_SetFifoIntCmd(base, kSpiRxFifoNearFullInt, true);
}
}
/* Modules that support 16-bit transfers but without FIFO support */
else
{
uint8_t byteToSend = 0;
/* SPI configured for 16-bit transfers, no FIFO */
if (bitCount == kSpi16BitMode)
{
uint8_t byteToSendLow = 0;
uint8_t byteToSendHigh = 0;
if (spiState->sendBuffer)
{
byteToSendLow = *(spiState->sendBuffer);
++spiState->sendBuffer;
/* If the extraByte flag is set and these are the last 2 bytes, then skip this */
if (!((spiState->extraByte) && (spiState->remainingSendByteCount == 2)))
{
byteToSendHigh = *(spiState->sendBuffer);
++spiState->sendBuffer;
}
}
SPI_HAL_WriteDataLow(base, byteToSendLow);
SPI_HAL_WriteDataHigh(base, byteToSendHigh);
spiState->remainingSendByteCount -= 2; /* decrement by 2 */
spiState->transferredByteCount += 2; /* increment by 2 */
}
/* SPI configured for 8-bit transfers, no FIFO */
else
{
if (spiState->sendBuffer)
{
byteToSend = *(spiState->sendBuffer);
++spiState->sendBuffer;
}
SPI_HAL_WriteDataLow(base, byteToSend);
--spiState->remainingSendByteCount;
++spiState->transferredByteCount;
}
/* Only enable the receive interrupt. This should be ok since SPI is a synchronous
* protocol, so every RX interrupt we get, we should be ready to send. However, since
* the SPI has a shift register and data buffer (for transmit and receive), things may not
* be cycle-to-cycle synchronous. To compensate for this, enabling the RX interrupt only
* ensures that we do indeed receive data before sending out the next data word. In the
* ISR we make sure to first check for the RX data buffer full before checking the TX
* data register empty flag.
*/
SPI_HAL_SetIntMode(base, kSpiRxFullAndModfInt, true);
}
#else /* For SPI modules that do not support 16-bit transfers */
/* Start the transfer by writing the first byte. If a send buffer was provided, the byte
* comes from there. Otherwise we just send a zero byte. Note that before writing to the
* data register, the status register must first be read, which was already performed above.
*/
uint8_t byteToSend = 0;
if (spiState->sendBuffer)
{
byteToSend = *(spiState->sendBuffer);
++spiState->sendBuffer;
}
SPI_HAL_WriteData(base, byteToSend);
--spiState->remainingSendByteCount;
++spiState->transferredByteCount;
/* Only enable the receive interrupt. This should be ok since SPI is a synchronous
* protocol, so every RX interrupt we get, we should be ready to send. However, since
* the SPI has a shift register and data buffer (for transmit and receive), things may not
* be cycle-to-cycle synchronous. To compensate for this, enabling the RX interrupt only
* ensures that we do indeed receive data before sending out the next data word. In the
* ISR we make sure to first check for the RX data buffer full before checking the TX
* data register empty flag.
*/
SPI_HAL_SetIntMode(base, kSpiRxFullAndModfInt, true);
#endif
return kStatus_SPI_Success;
}
int main (void)
{
uint8_t loopCount = 0;
uint32_t j;
uint32_t failCount = 0;
uint32_t calculatedBaudRate;
spi_master_state_t spiMasterState;
spi_master_user_config_t userConfig =
{
#if FSL_FEATURE_SPI_16BIT_TRANSFERS
.bitCount = kSpi8BitMode,
#endif
.polarity = kSpiClockPolarity_ActiveHigh,
.phase = kSpiClockPhase_FirstEdge,
.direction = kSpiMsbFirst,
.bitsPerSec = TRANSFER_BAUDRATE
};
// Init hardware
hardware_init();
// Init OSA layer.
OSA_Init();
PRINTF("\r\nSPI board to board blocking example");
PRINTF("\r\nThis example run on instance %d", (uint32_t)SPI_MASTER_INSTANCE);
PRINTF("\r\nBe sure master's SPI%d and slave's SPI%d are connected\r\n",
(uint32_t)SPI_MASTER_INSTANCE, (uint32_t)SPI_MASTER_INSTANCE);
// Init and setup baudrate for the master
SPI_DRV_MasterInit(SPI_MASTER_INSTANCE, &spiMasterState);
SPI_DRV_MasterConfigureBus(SPI_MASTER_INSTANCE,
&userConfig,
&calculatedBaudRate);
// Check if the configuration is correct
if (calculatedBaudRate > userConfig.bitsPerSec)
{
PRINTF("\r**Something failed in the master bus config \r\n");
return -1;
}
else
{
PRINTF("\r\nBaud rate in Hz is: %d\r\n", calculatedBaudRate);
}
while(1)
{
// Initialize the source buffer
for (j = 0; j < TRANSFER_SIZE; j++)
{
s_spiSourceBuffer[j] = j+loopCount;
}
// Reset the sink buffer
for (j = 0; j < TRANSFER_SIZE; j++)
{
s_spiSinkBuffer[j] = 0;
}
// Start transfer data to slave
if (SPI_DRV_MasterTransferBlocking(SPI_MASTER_INSTANCE, NULL, s_spiSourceBuffer,
NULL, TRANSFER_SIZE, MASTER_TRANSFER_TIMEOUT) == kStatus_SPI_Timeout)
{
PRINTF("\r\n**Sync transfer timed-out \r\n");
}
// Delay sometime to wait slave receive and send back data
OSA_TimeDelay(500U);
// Start receive data from slave by transmit NULL bytes
if (SPI_DRV_MasterTransferBlocking(SPI_MASTER_INSTANCE, NULL, NULL,
s_spiSinkBuffer, TRANSFER_SIZE, MASTER_TRANSFER_TIMEOUT) == kStatus_SPI_Timeout)
{
PRINTF("\r\n**Sync transfer timed-out \r\n");
}
// Verify the contents of the master sink buffer
// refer to the slave driver for the expected data pattern
failCount = 0; // reset failCount variable
for (j = 0; j < TRANSFER_SIZE; j++)
{
if (s_spiSinkBuffer[j] != s_spiSourceBuffer[j])
{
failCount++;
}
}
// Print out transmit buffer.
PRINTF("\r\nMaster transmit:");
for (j = 0; j < TRANSFER_SIZE; j++)
{
// Print 16 numbers in a line.
if ((j & 0x0F) == 0)
{
PRINTF("\r\n ");
}
PRINTF(" %02X", s_spiSourceBuffer[j]);
}
// Print out receive buffer.
PRINTF("\r\nMaster receive:");
for (j = 0; j < TRANSFER_SIZE; j++)
{
// Print 16 numbers in a line.
if ((j & 0x0F) == 0)
{
PRINTF("\r\n ");
}
PRINTF(" %02X", s_spiSinkBuffer[j]);
}
if (failCount == 0)
{
PRINTF("\r\n Spi master transfer succeed! \r\n");
}
else
{
PRINTF("\r\n **failures detected in Spi master transfer! \r\n");
}
// Wait for press any key.
PRINTF("\r\nPress any key to run again\r\n");
GETCHAR();
loopCount++;
}
}