topic LPC55S69 Continuous Data reception using SPI with DMA in LPC Microcontrollers

LPC55S69 Continuous Data reception using SPI with DMA

Akashlp — Fri, 01 Oct 2021 04:00:00 GMT

I wanted to read the sensor data continuously using SPI DMA mode. But with following code able to read the data only beginning and later will not be reading continuously. Please help to solve to read data continuously.

Following code is implement using SDK examples

/* DMA init */
DMA_Init(EXAMPLE_DMA);
/* Configure the DMA channel,priority and handle. */
DMA_EnableChannel(EXAMPLE_DMA, EXAMPLE_SPI_MASTER_TX_CHANNEL);
DMA_EnableChannel(EXAMPLE_DMA, EXAMPLE_SPI_MASTER_RX_CHANNEL);
DMA_SetChannelPriority(EXAMPLE_DMA, EXAMPLE_SPI_MASTER_TX_CHANNEL, kDMA_ChannelPriority0);
DMA_SetChannelPriority(EXAMPLE_DMA, EXAMPLE_SPI_MASTER_RX_CHANNEL, kDMA_ChannelPriority0);
DMA_CreateHandle(&masterTxHandle, EXAMPLE_DMA, EXAMPLE_SPI_MASTER_TX_CHANNEL);
DMA_CreateHandle(&masterRxHandle, EXAMPLE_DMA, EXAMPLE_SPI_MASTER_RX_CHANNEL);

spi_transfer_t masterXfer;

/* Set up handle for spi master */
SPI_MasterTransferCreateHandleDMA(EXAMPLE_SPI_MASTER, &masterHandle, SPI_MasterUserCallback, NULL, &masterTxHandle,
&masterRxHandle);

/* Start master transfer */
masterXfer.txData = (uint8_t *)&masterTxData;
masterXfer.rxData = (uint8_t *)&masterRxData;
masterXfer.dataSize = TRANSFER_SIZE * sizeof(masterTxData[0]);
masterXfer.configFlags = kSPI_FrameAssert;

if (kStatus_Success != SPI_MasterTransferDMA(EXAMPLE_SPI_MASTER, &masterHandle, &masterXfer))
{
PRINTF("There is an error when start SPI_MasterTransferDMA \r\n ");
}

Re: LPC55S69 Continuous Data reception using SPI with DMA

diego_charles — Tue, 05 Oct 2021 22:57:34 GMT

Hi @Akashlp

I hope that you are doing excellent!

Could you describe further the issue? Let me explain.

The spi_dma_b2b_transfer_master SDK example , has the following output , when testing with another LPC55 board :

Where 64 bytes are transferred (using masterXfer.dataSize = TRANSFER_SIZE * sizeof(masterTxData[0]) )

As far I understand, your goal is to initiate transfers with your sensor using DMA correct? Maybe with a variable transfer length.

Is the second transfer interrupted or halted? Or your sensor is not responding anything , so the received data is 0xFF or 0x00?

Thank you

Diego

Re: LPC55S69 Continuous Data reception using SPI with DMA

Akashlp — Fri, 08 Oct 2021 03:43:15 GMT

HI @diego_charles

My goals is to receive the sensor data continuously and read on SPI DMA buffer. The length of data sent by sensor is 24 bytes to 30 bytes.

Even need to send some configuration setting data to sensor from SPI DMA.

I am able to read only 64 bytes of data on SPI buffer and later buffer is not updating.

Re: LPC55S69 Continuous Data reception using SPI with DMA

diego_charles — Mon, 18 Oct 2021 22:20:24 GMT

Hi @Akashlp

Thank you for your reply and for your patience.

The other day, I replied with feedback on your internal ticket , with the same inquiry. Let me attach my reply , with several corrections , here.

The SPI DMA examples are coded to perform a single transfer between two boards. If you would like to perform multiple DMA transfers you will need to do some minor modifications on the examples.

If possible , I recommend you to test with two boards, your adaptation of the SPI DMA examples, this just to verify that your master code works as expected. Then perform communication with your SPI device.

As I did some tests with the LSPI DMA examples, I am attaching my code, just for reference.

Do not hesitate to let me know if you are still facing problems

Best regards,

Diego.