DMA Single Block

This sample demonstrates how to use SPI to transfer data via DMA. Communicate with the flash by SPI via DMA, and then send the data to the PC by UART.

Requirements

The sample supports the following development kits:

Development Kits

Hardware Platforms

Board Name

RTL87x2G HDK

RTL87x2G EVB

For more requirements, please refer to Quick Start.

Wiring

EVB is connected to W25Q128 module: connect P4_0(SCK) to CLK, P4_1(MISO) to DO, P4_2(MOSI) to DI, P4_3(CS) to CS#.

EVB is connected to FT232 module: connect P3_0 to RX pin of FT232 module and P3_1 to TX pin of FT232 module.

Hardware Introduction

The W25Q128 is a NOR Flash chip with SPI interface, which support the standard Serial Peripheral Interface (SPI), Dual/Quad I/O SPI as well as 2-clocks instruction cycle Quad Peripheral Interface (QPI).

Additionally, the device supports JEDEC standard manufacturer and device ID and SFDP Register, a 64-bit Unique Serial Number and three 256-bytes Security Registers.

Additional details can be found in the application guide for this device. In this example the device is used as slave for SPI communication test.

Building and Downloading

This sample can be found in the SDK folder:

Project file: samples\peripheral\spi\gdma_singleblock\proj\rtl87x2g\mdk

Project file: samples\peripheral\spi\gdma_singleblock\proj\rtl87x2g\gcc

To build and run the sample, follow the steps listed below:

  1. Open Sample Project File.

  2. To build the target, follow the steps listed on the Generating App Image in Quick Start.

  3. After a successful compilation, the app bin app_MP_xxx.bin will be generated in the directory mdk\bin or gcc\bin.

  4. To download app bin into EVB board, follow the steps listed on the MPTool Download in Quick Start.

  5. Press reset button on EVB board and it will start running.

Experimental Verification

  1. After initialization, the DMA starts to carry TX data. When the transmission completes, it enters the GDMA TX interrupt and prints the LOG.

    GDMA_TX_Channel_Handler: TX completed!

  2. The SPI receives the data sent back from the external flash and the DMA starts to carry the RX data. When the handling is finished, it enters the GDMA RX interrupt and prints the length of the acquired data and the data information.

    GDMA_RX_Channel_Handler!
[io_gdma] io_handle_gdma_msg: read data complete,data_len = 3
GDMA_Recv_Buffer[0] = 0x000000ef
GDMA_Recv_Buffer[1] = 0x00000040
GDMA_Recv_Buffer[2] = 0x00000018

  3. The UART sends the received data via FT232 to the serial assistant on the PC, and receive the JEDEC_ID information on the serial assistant.

Here should be a picture of the message received by the serial port assistant

Message received by the Serial Assistant

Code Overview

This chapter will be introduced according to the following several parts:

  1. Source Code Directory.

  2. Peripheral initialization will be introduced in chapter Initialization .

  3. Functional implementation after initialization will be introduced in chapter Functional Implementation .

Source Code Directory

  • Project Directory: sdk\samples\peripheral\spi\gdma_singleblock\proj

  • Source Code Directory: sdk\samples\peripheral\spi\gdma_singleblock\src

Source files are currently categorized into several groups as below.

└── Project: gdma_singleblock
    └── secure_only_app
        └── Device                   includes startup code
            ├── startup_rtl.c
            └── system_rtl.c
        ├── CMSIS                    includes CMSIS header files
        ├── CMSE Library             Non-secure callable lib
        ├── Lib                      includes all binary symbol files that user application is built on
            └── rtl87x2g_io.lib
        ├── Peripheral               includes all peripheral drivers and module code used by the application
            ├── rtl_rcc.c
            ├── rtl_pinmux.c
            ├── rtl_nvic.c
            ├── rtl_uart.c
            ├── rtl_gdma.c
            └── rtl_spi.c
        └── APP                      includes the ble_peripheral user application implementation
            ├── main_ns.c
            ├── io_uart.c
            ├── io_gdma.c
            └── io_spi.c

Initialization

The initialization process includes board_spi_init , board_uart_init , driver_uart_init and driver_spi_gdma_init.

board_spi_init contains the PAD and PINMUX settings of SPI.

  1. Config PAD: Set pins as PINMUX mode, PowerOn, internal pull-up.

  2. Config PINMUX: Assign pins for SPI0_CLK_MASTER, SPI0_MO_MASTER, SPI0_MI_MASTER, SPI0_CSN_0_MASTER functions respectively.

board_uart_init contains the PAD and PINMUX settings of UART.

  1. Config PAD: Set pins as PINMUX mode, PowerOn, internal pull-up.

  2. Config PINMUX: Assign pins for UART0_TX, UART0_RX functions respectively.

driver_uart_init contains the initialization of UART peripheral.

  1. Enable PCC clock.

  2. Set no parity.

  3. Set stop bits 1 bit.

  4. Set word lenth 8 bit.

RCC_PeriphClockCmd(APBPeriph_UART0, APBPeriph_UART0_CLOCK, ENABLE);
...
UART_InitStruct.UART_Parity         = UART_PARITY_NO_PARTY;
UART_InitStruct.UART_StopBits       = UART_STOP_BITS_1;
UART_InitStruct.UART_WordLen        = UART_WORD_LENGTH_8BIT;
UART_InitStruct.UART_RxThdLevel     = 16;
UART_InitStruct.UART_IdleTime       = UART_RX_IDLE_2BYTE;

driver_spi_gdma_init contains the initialization of SPI and GDMA peripheral.

  1. Initialize the SPI peripheral:

    1. Enable PCC clock.

    2. Set the communication mode to EEPROM mode.

    3. Refer to SPI Polling initialization flow for other basic settings.

    4. Set NDF to GDMA_READ_SIZE_MAX.

    5. Enable GDMA TX and RX for SPI.

    6. Set the TxWaterlevel to SPI_TX_FIFO_SIZE - 8, set the RxWaterlevel to 8 - 1.

RCC_PeriphClockCmd(APBPERIPH_SPI, APBPERIPH_SPI_CLOCK, ENABLE);
...
SPI_InitStructure.SPI_Direction   = SPI_Direction_EEPROM;
...
SPI_InitStructure.SPI_NDF         = GDMA_READ_SIZE_MAX;
SPI_InitStructure.SPI_RxDmaEn     = ENABLE;
SPI_InitStructure.SPI_TxDmaEn     = ENABLE;
SPI_InitStructure.SPI_RxWaterlevel = 8 - 1;
SPI_InitStructure.SPI_TxWaterlevel = SPI_TX_FIFO_SIZE - 8;

  1. Initialize the GDMA TX:

    1. Enable PCC clock.

    2. Use GDMA channel 3.

    3. Transfer direction is memory to peripheral transfer.

    4. Set the source address to increment and the destination address to be fixed.

    5. Set the source and destination MSize to GDMA_Msize_8.

    6. The source address is GDMA_WriteCmdBuffer, and the destination address is FLASH_SPI->SPI_DR.

    7. Configure the GDMA TX total transfer completion interrupt GDMA_INT_Transfer.

RCC_PeriphClockCmd(APBPeriph_GDMA, APBPeriph_GDMA_CLOCK, ENABLE);
...
GDMA_InitStruct.GDMA_ChannelNum          = GDMA_TX_CHANNEL_NUM;
GDMA_InitStruct.GDMA_DIR                 = GDMA_DIR_MemoryToPeripheral;
GDMA_InitStruct.GDMA_SourceInc           = DMA_SourceInc_Inc;
GDMA_InitStruct.GDMA_DestinationInc      = DMA_DestinationInc_Fix;
GDMA_InitStruct.GDMA_SourceMsize         = GDMA_Msize_8;
GDMA_InitStruct.GDMA_DestinationMsize    = GDMA_Msize_8;
...
GDMA_InitStruct.GDMA_SourceAddr          = (uint32_t)GDMA_WriteCmdBuffer;
GDMA_InitStruct.GDMA_DestinationAddr     = (uint32_t)FLASH_SPI->SPI_DR;
...
GDMA_INTConfig(GDMA_TX_CHANNEL_NUM, GDMA_INT_Transfer, ENABLE);
...

  1. Initialize GDMA RX:

    1. Enable PCC clock.

    2. Use GDMA channel 0.

    3. Transfer direction is peripheral to memory transfer.

    4. Set the source address to be fixed and the destination address to be incremented.

    5. Set the source and destination MSize to GDMA_Msize_8.

    6. The source address is FLASH_SPI->SPI_DR and the destination address is GDMA_Recv_Buffer.

    7. Configure the GDMA RX total transfer completion interrupt GDMA_INT_Transfer.

RCC_PeriphClockCmd(APBPeriph_GDMA, APBPeriph_GDMA_CLOCK, ENABLE);
...
GDMA_InitStruct.GDMA_ChannelNum          = GDMA_RX_CHANNEL_NUM;
GDMA_InitStruct.GDMA_DIR                 = GDMA_DIR_PeripheralToMemory;
GDMA_InitStruct.GDMA_SourceInc           = DMA_SourceInc_Fix;
GDMA_InitStruct.GDMA_DestinationInc      = DMA_DestinationInc_Inc;
GDMA_InitStruct.GDMA_SourceMsize         = GDMA_Msize_8;
GDMA_InitStruct.GDMA_DestinationMsize    = GDMA_Msize_8;
...
GDMA_InitStruct.GDMA_SourceAddr          = (uint32_t)FLASH_SPI->SPI_DR;
GDMA_InitStruct.GDMA_DestinationAddr     = (uint32_t)GDMA_Recv_Buffer;
...
GDMA_INTConfig(GDMA_RX_CHANNEL_NUM, GDMA_INT_Transfer, ENABLE);

  1. Set the data receive length in EEPORM transmission mode to 3 (JEDEC_ID length is 3), enable SPI.

  2. Set the Buffer Size for GDMA TX and RX, enable RX GDMA and enable TX GDMA.

SPI_SetReadLen(SPI0, 3);
SPI_Cmd(FLASH_SPI, ENABLE);
GDMA_SetBufferSize(GDMA_RX_Channel, 3);
GDMA_Cmd(GDMA_RX_CHANNEL_NUM, ENABLE);

/* Send read data command */
GDMA_SetBufferSize(GDMA_TX_Channel, 1);
GDMA_SetSourceAddress(GDMA_TX_Channel, (uint32_t)GDMA_WriteCmdBuffer);
GDMA_Cmd(GDMA_TX_CHANNEL_NUM, ENABLE);

Functional Implementation

  1. After enabling the GDMA TX channel, trigger the GDMA TX transfer, trigger the GDMA_INT_Transfer interrupt after the transfer is completed, and execute the interrupt handler function GDMA_RX_Channel_Handler.

    1. Disable the GDMA TX channel interrupt, print the entry interrupt message, clear the GDMA interrupt pending bit, and enable GDMA_INT_Transfer interrupt.

  2. After receiving the message of GDMA TX transfer, flash transfers the internal information back through the GDMA RX channel. Once the transfer is complete, it triggers the GDMA_INT_Transfer interrupt, and enters the interrupt handler function GDMA_RX_Channel_Handler.

    1. Disable the GDMA TX channel interrupt, print the GDMA_Recv_Buffer information.

    2. Execute uart_senddata_continuous to send the GDMA_Recv_Buffer information to the PC via UART0.

GDMA_INTConfig(GDMA_RX_CHANNEL_NUM, GDMA_INT_Transfer, DISABLE);

uint16_t data_len = (GDMA_TRANSFER_SIZE);
for (uint16_t i = 0; i < GDMA_TRANSFER_SIZE; i++)
{
    DBG_DIRECT("GDMA_Recv_Buffer[%d] = 0x%x", i, GDMA_Recv_Buffer[i]);
}
uart_senddata_continuous(UART0, GDMA_Recv_Buffer, data_len);

GDMA_ClearINTPendingBit(GDMA_RX_CHANNEL_NUM, GDMA_INT_Transfer);
GDMA_INTConfig(GDMA_RX_CHANNEL_NUM, GDMA_INT_Transfer, ENABLE);

Troubleshooting

When the SPI frequency to be used is high (greater than 10MHz), it is recommended to use DMA to transfer data. If it is found that the CS line is pulled up during data transfer, the MSize of GDMA can be increased to improve the transfer efficiency of DMA.