/* Queue up DMA descriptors and buffers for UART RX */
static void dmaRXQueue(void)
{
int i;
/* Linked list of descriptors that map to the 3 receive buffers */
for (i = 0; i < UARTRXDESC; i++) {
/* Setup next descriptor */
if (i == (UARTRXDESC - 1)) {
/* Wrap descriptors */
dmaRXDesc[i].next = DMA_ADDR(&dmaRXDesc[0]);
}
else {
dmaRXDesc[i].next = DMA_ADDR(&dmaRXDesc[i + 1]);
}
/* Create a descriptor for the data */
dmaRXDesc[i].source = DMA_ADDR(&LPC_USART0->RXDATA) + 0; /* Byte aligned */
dmaRXDesc[i].dest = DMA_ADDR(&dmaRXBuffs[i][0] + UARTRXBUFFSIZE - 1);
/* Setup transfer configuration */
dmaRXDesc[i].xfercfg = DMA_XFERCFG_CFGVALID | DMA_XFERCFG_SETINTA |
DMA_XFERCFG_WIDTH_8 | DMA_XFERCFG_SRCINC_0 |
DMA_XFERCFG_DSTINC_1 | DMA_XFERCFG_RELOAD |
DMA_XFERCFG_XFERCOUNT(UARTRXBUFFSIZE);
}
/* Setup transfer descriptor and validate it */
Chip_DMA_SetupTranChannel(LPC_DMA, DMAREQ_USART0_RX, &dmaRXDesc[0]);
/* Setup data transfer */
Chip_DMA_SetupChannelTransfer(LPC_DMA, DMAREQ_USART0_RX,
dmaRXDesc[0].xfercfg);
Chip_DMA_SetValidChannel(LPC_DMA, DMAREQ_USART0_RX);
Chip_DMA_SWTriggerChannel(LPC_DMA, DMAREQ_USART0_RX);
}
/* Setup and start a DMA transfer */
static setupI2CDMAXfer(void *buff, uint8_t bytes, bool tx)
{
/* Enable DMA for I2C controller */
I2C_SENSOR_BUS->MSTCTL = I2C_MSTCTL_MSTDMA;
/* Master to slave */
if (tx) {
dmaI2CMDesc.source = DMA_ADDR(buff) + bytes - 1;
dmaI2CMDesc.dest = DMA_ADDR(&I2C_SENSOR_BUS->MSTDAT);
dmaI2CMDesc.next = DMA_ADDR(0);
dmaI2CMDesc.xfercfg = DMA_XFERCFG_CFGVALID | DMA_XFERCFG_SETINTA |
DMA_XFERCFG_SWTRIG | DMA_XFERCFG_WIDTH_8 | DMA_XFERCFG_SRCINC_1 |
DMA_XFERCFG_DSTINC_0 | DMA_XFERCFG_XFERCOUNT(bytes);
}
else {
dmaI2CMDesc.source = DMA_ADDR(&I2C_SENSOR_BUS->MSTDAT);
dmaI2CMDesc.dest = DMA_ADDR(buff) + bytes - 1;
dmaI2CMDesc.next = DMA_ADDR(0);
dmaI2CMDesc.xfercfg = DMA_XFERCFG_CFGVALID | DMA_XFERCFG_SETINTA |
DMA_XFERCFG_SWTRIG | DMA_XFERCFG_WIDTH_8 | DMA_XFERCFG_SRCINC_0 |
DMA_XFERCFG_DSTINC_1 | DMA_XFERCFG_XFERCOUNT(bytes);
}
/* Setup transfer descriptor and validate it */
Chip_DMA_SetupTranChannel(LPC_DMA, I2C_SENSOR_BUS_DMAID, &dmaI2CMDesc);
/* Setup data transfer */
Chip_DMA_SetupChannelTransfer(LPC_DMA, I2C_SENSOR_BUS_DMAID, dmaI2CMDesc.xfercfg);
Chip_DMA_SetValidChannel(LPC_DMA, I2C_SENSOR_BUS_DMAID);
}
/**
* @brief DMA Interrupt Handler
* @return None
*/
void DMA_IRQHandler(void)
{
uint32_t errors, pending;
/* Get DMA error and interrupt channels */
errors = Chip_DMA_GetErrorIntChannels(LPC_DMA);
pending = Chip_DMA_GetActiveIntAChannels(LPC_DMA);
/* Check DMA interrupts of UART 0 TX channel */
if ((errors | pending) & (1 << DMAREQ_USART0_TX)) {
/* Clear DMA interrupt for the channel */
Chip_DMA_ClearActiveIntAChannel(LPC_DMA, DMAREQ_USART0_TX);
/* Handle errors if needed */
if (errors & (1 << DMAREQ_USART0_TX)) {
/* DMA error, channel needs to be reset */
dmaClearChannel(DMAREQ_USART0_TX);
dmaTXSetup();
}
else {
/* Descriptor is consumed */
countTXDescUsed--;
}
/* Is another DMA descriptor waiting that was not chained? */
if (countTXDescUsed > 0) {
nextTXDesc++;
/* Setup transfer descriptor and validate it */
Chip_DMA_SetupTranChannel(LPC_DMA, DMAREQ_USART0_TX, &dmaTXDesc[nextTXDesc]);
/* Setup data transfer */
Chip_DMA_SetupChannelTransfer(LPC_DMA, DMAREQ_USART0_TX,
dmaTXDesc[nextTXDesc].xfercfg);
Chip_DMA_SetValidChannel(LPC_DMA, DMAREQ_USART0_TX);
}
}
/* Check DMA interrupts of UART 0 RX channel */
if ((errors | pending) & (1 << DMAREQ_USART0_RX)) {
/* Clear DMA interrupt for the channel */
Chip_DMA_ClearActiveIntAChannel(LPC_DMA, DMAREQ_USART0_RX);
/* Handle errors if needed */
if (errors & (1 << DMAREQ_USART0_RX)) {
/* DMA error, channel needs to be reset */
dmaClearChannel(DMAREQ_USART0_RX);
dmaRXSetup();
dmaRXQueue();
}
else {
uartRxAvail = true;
}
}
}
/* Send data via the UART */
static bool dmaTXSend(uint8_t *data, int bytes)
{
/* Disable the DMA IRQ to prevent race conditions with shared data */
NVIC_DisableIRQ(DMA_IRQn);
/* This is a limited example, limit descriptor and byte count */
if ((countTXDescUsed >= UARTTXDESC) || (bytes > 1024)) {
/* Re-enable the DMA IRQ */
NVIC_EnableIRQ(DMA_IRQn);
/* All DMA descriptors are used, so just exit */
return false;
}
else if (countTXDescUsed == 0) {
/* No descriptors are currently used, so take the first one */
nextTXDesc = 0;
}
/* Create a descriptor for the data */
dmaTXDesc[countTXDescUsed].source = DMA_ADDR(data + bytes - 1); /* Last address here */
dmaTXDesc[countTXDescUsed].dest = DMA_ADDR(&LPC_USART0->TXDATA); /* Byte aligned */
/* If there are multiple buffers with non-contiguous addresses, they can be chained
together here (it is recommended to only use the DMA_XFERCFG_SETINTA on the
last chained descriptor). If another TX buffer needs to be sent, the DMA
IRQ handler will re-queue and send the buffer there without using chaining. */
dmaTXDesc[countTXDescUsed].next = DMA_ADDR(0);
/* Setup transfer configuration */
dmaTXDesc[countTXDescUsed].xfercfg = DMA_XFERCFG_CFGVALID | DMA_XFERCFG_SETINTA |
DMA_XFERCFG_SWTRIG | DMA_XFERCFG_WIDTH_8 | DMA_XFERCFG_SRCINC_1 |
DMA_XFERCFG_DSTINC_0 | DMA_XFERCFG_XFERCOUNT(bytes);
/* If a transfer is currently in progress, then stop here and let the DMA
handler re-queue the next transfer. Otherwise, start the transfer here. */
if (countTXDescUsed == 0) {
/* Setup transfer descriptor and validate it */
Chip_DMA_SetupTranChannel(LPC_DMA, DMAREQ_USART0_TX, &dmaTXDesc[countTXDescUsed]);
/* Setup data transfer */
Chip_DMA_SetupChannelTransfer(LPC_DMA, DMAREQ_USART0_TX,
dmaTXDesc[countTXDescUsed].xfercfg);
Chip_DMA_SetValidChannel(LPC_DMA, DMAREQ_USART0_TX);
}
/* Update used descriptor count */
countTXDescUsed++;
/* Re-enable the DMA IRQ */
NVIC_EnableIRQ(DMA_IRQn);
return true;
}