DBI-C
This sample demonstrates the application of the DBI-C interface of the LCDC peripheral. The DBI-C interface is usually known as QSPI.
Requirements
The sample supports the following development kits:
Hardware Platforms |
Board Name |
|---|---|
RTL87x2G HDK |
RTL87x2G EVB |
For more requirements, please refer to Quick Start.
Wiring
A QSPI screen or logical analyzer is required.
Connect P3_6 to the Reset pin.
Connect P4_2 to D0 pin.
Connect P4_1 to D1 pin.
Connect P3_2 to D2 pin.
Connect P3_3 to D3 pin.
Connect P4_3 to CS pin.
Connect P4_0 to CLK pin.
Connect P0_5 to TE pin if available.
Or connect all the pins to a logic analyzer instead.
Building and Downloading
This sample can be found in the SDK folder:
Project file: samples\peripheral\lcdc\lcdc_qspi\proj\rtl87x2g\mdk
Project file: samples\peripheral\lcdc\lcdc_qspi\proj\rtl87x2g\gcc
To build and run the sample, follow the steps listed below:
Open Sample Project File.
To build the target, follow the steps listed on the Generating App Image in Quick Start.
After a successful compilation, the app bin
app_MP_xxx.binwill be generated in the directorymdk\bin.To download app bin into EVB board, follow the steps listed on the MP Tool Download in Quick Start.
Press the reset button on the EVB board and it will start running.
Experimental Verification
The screen displays green or the correct waveform is observed in the logical analyzer.
Code Overview
This chapter will be introduced according to the following several parts：
Peripheral initialization will be introduced in chapter Initialization.
Functional implementation after initialization will be introduced in chapter Functional implementation.
Source Code Directory
Project directory:
sdk\samples\peripheral\lcdc\lcdc_qspi\projSource code directory:
sdk\samples\peripheral\lcdc\lcdc_qspi\src
Source files are currently categorized into several groups as below.
└── Project: qspi
└── lcdc
├── config includes project construct configuration
├── display includes the peripheral drivers related with display
└── 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
├── peripheral includes all peripheral drivers and module code used by the application
└── APP source code of LCDC qspi sample
├── main_ns.c
└── icna3311_280x456_qspi.c driver of LCD screen
Initialization
The initialization process is included in rtk_lcd_hal_init().
Enable clock of LCDC, and select suitable clock source.
/* config LCD dev info */
RCC_PeriphClockCmd(APBPeriph_DISP, APBPeriph_DISP_CLOCK, ENABLE);
//from XTAL SOURCE = 40M
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.disp_ck_en = 1;
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.disp_func_en = 1;
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.r_disp_mux_clk_cg_en = 1;
//From PLL1, SOURCE = 100M
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.r_disp_div_en = 1;
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.r_disp_clk_src_sel0 = 0; //pll1_peri(0) or pll2(1, pll2 = 160M)
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.r_disp_clk_src_sel1 = 1; //pll(1) or xtal(0)
PERIBLKCTRL_PERI_CLK->u_324.BITS_324.r_disp_div_sel = 1; //div
Configure pins to be used.
Pad_Config(LCD_QSPI_RST, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_D0, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_D1, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_D2, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_D3, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_CS, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_CLK, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCD_QSPI_TE, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Dedicated_Config(LCD_QSPI_RST, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_D0, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_D1, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_D2, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_D3, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_CS, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_CLK, ENABLE);
Pad_Dedicated_Config(LCD_QSPI_TE, ENABLE);
Select color format and DBI-C interface.
LCDC_InitTypeDef lcdc_init = {0};
lcdc_init.LCDC_Interface = LCDC_IF_DBIC;
lcdc_init.LCDC_GroupSel = 1; //QFN88 2 - QFN68 1
lcdc_init.LCDC_PixelInputFormat = LCDC_INPUT_RGB565;
lcdc_init.LCDC_PixelOutputFormat = LCDC_OUTPUT_RGB565;
lcdc_init.LCDC_PixelBitSwap = LCDC_SWAP_BYPASS;
lcdc_init.LCDC_TeEn = ENABLE;
lcdc_init.LCDC_TePolarity = LCDC_TE_EDGE_FALLING;
lcdc_init.LCDC_TeInputMux = LCDC_TE_LCD_INPUT;
lcdc_init.LCDC_DmaThreshold = 112;
LCDC_Init(&lcdc_init);
Initialize DBI-C interface, select clock divider, polarity and phase.
LCDC_DBICCfgTypeDef dbic_init = {0};
dbic_init.DBIC_SPEED_SEL = 1;
dbic_init.DBIC_TxThr = 0; //0 or 4
dbic_init.DBIC_RxThr = 0;
dbic_init.SCPOL = DBIC_SCPOL_LOW;
dbic_init.SCPH = DBIC_SCPH_1Edge;
DBIC_Init(&dbic_init);
Control Reset pin to finish reset procedure.
LCDC_LCD_SET_RST(false);
platform_delay_ms(100);
LCDC_LCD_SET_RST(true);
platform_delay_ms(120);
LCDC_LCD_SET_RST(false);
platform_delay_ms(50);
If the screen needs extra information for initialization, send command and data through the DBI-C interface to the screen.
Tip
About how to send command and data, refer to Troubleshooting
Functional Implementation
Function
rtk_lcd_hal_set_window()is used to set the window of screen that is to be updated. The following example demonstrates a window starting from point (0,0) with a width of 280 and a height of 456:
rtk_lcd_hal_set_window(0, 0, 280, 456);
Send data with a certain length by function
rtk_lcd_hal_start_transfer().In
rtk_lcd_hal_start_transfer(), configure DMA with the desired parameters.
LCDC_DMA_InitTypeDef LCDC_DMA_InitStruct = {0};
LCDC_DMA_StructInit(&LCDC_DMA_InitStruct);
LCDC_DMA_InitStruct.LCDC_DMA_ChannelNum = LCDC_DMA_CHANNEL_NUM;
LCDC_DMA_InitStruct.LCDC_DMA_DIR = 4;
LCDC_DMA_InitStruct.LCDC_DMA_SourceInc = LCDC_DMA_SourceInc_Inc;
LCDC_DMA_InitStruct.LCDC_DMA_DestinationInc = LCDC_DMA_DestinationInc_Fix;
LCDC_DMA_InitStruct.LCDC_DMA_SourceDataSize = LCDC_DMA_DataSize_Word;
LCDC_DMA_InitStruct.LCDC_DMA_DestinationDataSize = LCDC_DMA_DataSize_Word;
LCDC_DMA_InitStruct.LCDC_DMA_SourceMsize = LCDC_DMA_Msize_8;
LCDC_DMA_InitStruct.LCDC_DMA_DestinationMsize = LCDC_DMA_Msize_8;
LCDC_DMA_InitStruct.LCDC_DMA_SourceAddr = (uint32_t)buf;
LCDC_DMA_InitStruct.LCDC_DMA_Multi_Block_En = 0;
LCDC_DMA_Init(LCDC_DMA_CHANNEL_INDEX, &LCDC_DMA_InitStruct);
Reset DMA registers and assign with new value.
LCDC_ClearDmaFifo();
LCDC_ClearTxPixelCnt();
LCDC_SwitchMode(LCDC_AUTO_MODE);
LCDC_SwitchDirect(LCDC_TX_MODE);
LCDC_SetTxPixelLen(len);
Enable DMA. If TE signal is available, start DMA transmission when the TE signal arrives.
LCDC_Cmd(ENABLE);
LCDC_DMAChannelCmd(LCDC_DMA_CHANNEL_NUM, ENABLE);
LCDC_DmaCmd(ENABLE);
#if (TE_VALID == 1)
LCDC_TeCmd(ENABLE);
#endif
#if (TE_VALID == 0)
LCDC_AutoWriteCmd(ENABLE);
#endif
Use function
rtk_lcd_hal_transfer_done()to wait for DMA to finish transmission.
Troubleshooting
Send Data Through DBI-C
Take function
qspi_write()as an example of sending command and data.Set the number of data lanes and the direction of data transmission.
DBIC_Cmd(DISABLE);//disable DBIC
DBIC->CTRLR0 &= ~(BIT_CMD_CH(3) | BIT_ADDR_CH(3) | BIT_DATA_CH(3));//SET CHANNEL NUM
DBIC->CTRLR0 &= ~(BIT_TMOD(3)); //tx mode
Send the length of command and address.
DBIC_CmdLength(1);
DBIC_AddrLength(3);
DBIC_TX_NDF(len - 4);
DBIC_Cmd(ENABLE);
Write data to DR register and wait until DBI-C interface enters idle state.
for (uint32_t i = 0; i < len; i++)
{
DBIC->DR[0].byte = buf[i];
}
while (DBIC->SR & BIT0); // wait bus busy
DBIC_Cmd(DISABLE);//disable DBIC