SPI Slave Write DMA

The sample demonstrates how SPI0 slave sends data by GDMA and receives data by interrupt. The chip sends data to the SPI master and receives data from it.

Requirements

For hardware requirements, please refer to the Requirements.

Wiring

Connect P1_0 (slave SCK) to SCK of SPI master device, connect P1_1 (slave MOSI) to MOSI of SPI master device, connect P2_1 (slave MISO) to MISO of SPI master device, and connect P2_2 (slave CS) to CS of SPI master device. The hardware connection of SPI sample code is shown in the figure below.

SPI Sample Code Hardware Connection Diagram

Configurations

1. The following macros can be configured to modify pin definitions.

   • #define PIN_SPI_SCK P1_0

   • #define PIN_SPI_MOSI P1_1

   • #define PIN_SPI_MISO P2_1

   • #define PIN_SPI_CS P2_2

2. The entry function are as follows, call this function in main() to run this sample code. For more details, please refer to the Initialization.

   spi_slave_write_demo();
   

Building and Downloading

For building and downloading, please refer to the Building and Downloading.

Experimental Verification

1. Press the Reset button on the EVB, the data in array send_buf is sent to SPI TX FIFO.

2. When master device sends data to the chip, the send_buf can be sent to SPI master. When completing the transmission, it enters the GDMA interrupt and prints log.

   spi_slave_tx_dma_handler
   

3. And the chip stores the received data in array SPI_ReadINTBuf and prints log in Debug Analyzer.

   spi_slave_handler: SPI_ReadINTBuf[0] 0x%x
   ...
   spi_slave_handler: SPI_ReadINTBuf[15] 0x%x
   

Code Overview

Source Code Directory

• For project directory, please refer to Source Code Directory.

• Source code directory: sdk\src\sample\io_demo\spi\slave\spi_slave_write_demo.c .

SPI Initialization Flow

The initialization flow for peripherals can refer to Initialization Flow.

SPI initialization flow is shown in the following figure.

SPI Initialization Flow Chart

1. Call Pad_Config() and Pinmux_Config() to initialize the pins.

   static void board_spi_pinmux_init(void)
   {
      Pinmux_Config(PIN_SPI_SCK, SPI_CLK_SLAVE);
      Pinmux_Config(PIN_SPI_MOSI, SPI_MO_SLAVE);
      Pinmux_Config(PIN_SPI_MISO, SPI_MI_SLAVE);
      Pinmux_Config(PIN_SPI_CS, SPI_SS_N_0_SLAVE);
   
      Pad_Config(PIN_SPI_SCK, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_DISABLE,
                  PAD_OUT_HIGH);
      Pad_Config(PIN_SPI_MOSI, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_DISABLE,
                  PAD_OUT_HIGH);
      Pad_Config(PIN_SPI_MISO, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_DISABLE,
                  PAD_OUT_HIGH);
      Pad_Config(PIN_SPI_CS, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_NONE, PAD_OUT_DISABLE, PAD_OUT_HIGH);
   }
   

2. Call RCC_PeriphClockCmd() to enable the SPI clock and function.

3. Initialize the SPI peripheral:

   1. Define the SPI_InitTypeDef type SPI_InitStructure, and call SPI_StructInit() to pre-fill SPI_InitStructure with default values.

   2. Modify the SPI_InitStructure parameters as needed. The SPI initialization parameter configuration is shown in the table below.

   3. Call SPI_Init() to initialize the SPI peripheral.

   SPI Initialization Parameters

   SPI Hardware Parameters	Setting in the SPI_InitStructure	SPI
   Direction	SPI_InitTypeDef::SPI_Direction	SPI_Direction_FullDuplex
   Device Role (SPI Master or SPI Slave)	SPI_InitTypeDef::SPI_Mode	SPI_Mode_Slave
   Data Frame Size	SPI_InitTypeDef::SPI_DataSize	SPI_DataSize_8b
   Clock Polarity	SPI_InitTypeDef::SPI_CPOL	SPI_CPOL_High
   Clock Phase	SPI_InitTypeDef::SPI_CPHA	SPI_CPHA_1Edge
   Clock Div	SPI_InitTypeDef::SPI_BaudRatePrescaler	100
   Receive FIFO Threshold Level	SPI_InitTypeDef::SPI_RxThresholdLevel	0
   TX Water Level	SPI_InitTypeDef::SPI_TxWaterlevel	7

4. Call RamVectorTableUpdate() to register SPI slave interrupt handler.

5. Call SPI_INTConfig() to enable RX FIFO full interrupt SPI_INT_RXF.

6. Call NVIC_Init to enable NVIC of SPI.

7. Call SPI_Cmd() to enable SPI.

TX DMA Initialization Flow

The initialization flow for peripherals can refer to Initialization Flow.

SPI TX DMA initialization flow is shown in the following figure.

SPI TX DMA Initialization Flow Chart

1. Call RCC_PeriphClockCmd() to enable the GDMA clock and function.

2. Call GDMA_channel_request to request a free GDMA channel and register the GDMA interrupt handler.

3. Initialize the GDMA peripheral:

   1. Define the GDMA_InitTypeDef type GDMA_InitStruct, and call GDMA_StructInit() to pre-fill GDMA_InitStruct with default values.

   2. Modify the GDMA_InitStruct parameters as needed. The GDMA initialization parameter configuration is shown in the table below.

   3. Call GDMA_Init to initialize the GDMA peripheral.

   GDMA Initialization Parameters

   GDMA Hardware Parameters	Setting in the GDMA_InitStruct	GDMA
   Channel Num	GDMA_InitTypeDef::GDMA_ChannelNum	SPI_SLAVE_TX_DMA_CHANNEL_NUM
   Transfer Direction	GDMA_InitTypeDef::GDMA_DIR	GDMA_DIR_MemoryToPeripheral
   Buffer Size	GDMA_InitTypeDef::GDMA_BufferSize	TEST_SIZE
   Source Address Increment or Decrement	GDMA_InitTypeDef::GDMA_SourceInc	DMA_SourceInc_Inc
   Destination Address Increment or Decrement	GDMA_InitTypeDef::GDMA_DestinationInc	DMA_DestinationInc_Fix
   Source Data Size	GDMA_InitTypeDef::GDMA_SourceDataSize	GDMA_DataSize_Byte
   Destination Data Size	GDMA_InitTypeDef::GDMA_DestinationDataSize	GDMA_DataSize_Byte
   Source Burst Transaction Length	GDMA_InitTypeDef::GDMA_SourceMsize	GDMA_Msize_1
   Destination Burst Transaction Length	GDMA_InitTypeDef::GDMA_DestinationMsize	GDMA_Msize_1
   Source Address	GDMA_InitTypeDef::GDMA_SourceAddr	sendbuf
   Destination Address	GDMA_InitTypeDef::GDMA_DestinationAddr	SPI0->DR
   Destination Handshake	GDMA_InitTypeDef::GDMA_DestHandshake	GDMA_Handshake_SPI0_TX

4. Call GDMA_INTConfig() to enable GDMA transfer complete interrupt GDMA_INT_Transfer.

5. Call NVIC_Init to enable NVIC of GDMA.

Functional Implementation

Slave Send Data by DMA

1. Call SPI_GDMACmd() to disable and then enable SPI GDMA RX Function.

2. Call GDMA_Cmd to enable DMA transfers.

3. When GDMA transfer is completed, transfer complete interrupt is triggered. Then call GDMA_ClearINTPendingBit() to clear GDMA_INT_Transfer interrupt.

Slave Receive Data by Interrupt

Please refer to Receive Data by Interrupt.