EDPI

Overview

This sample demonstrates the application of the EDPI interface of the LCDC peripheral.

Requirements

The sample supports the following development kits:

Development Kit
Hardware Platforms	Board Name
RTL87x2G HDK	RTL87x2G EVB

For more requirements, please refer to Quick Start.

Wiring

QSPI screen or logical analyzer is required.

Connect P0_2 to the WRCLK pin.
Connect P1_5 to the HSYNC pin.
Connect P0_1 to the VSYNC pin.
Connect P0_0 to the DE pin.
For other data pins, refer to EK9716_800480_rgb.h.

Or connect all the pins to a logical analyzer instead.

Building and Downloading

This sample can be found in the SDK folder:

Keil

Project file: samples\peripheral\lcdc\lcdc_edpi\proj\rtl87x2g\mdk

GCC

Project file: samples\peripheral\lcdc\lcdc_edpi\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.bin will be generated in the directory mdk\bin.
To download app bin into the 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 correct waveform is observed in the logical analyzer.

Code Overview

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

Source code directory.
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_edpi\proj
Source code directory: sdk\samples\peripheral\lcdc\lcdc_edpi\src

Source files are currently categorized into several groups as below.

└── Project: edpi
    └── lcdc
        ├── config                       includes project construct configuration
        ├── display                      includes the peripheral drivers related to 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 edpi sample
            ├── main_ns.c
            └── EK9716_800480_rgb.c  driver of LCD screen

Initialization

The initialization process is included in lcd_pad_and_clk_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 = 0; //div

Initialize all the pins to be used.

Pad_Config(LCDC_RGB_WRCLK, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE,
           PAD_OUT_HIGH);
Pad_Config(LCDC_HSYNC, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCDC_VSYNC, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);
Pad_Config(LCDC_CSN_DE, PAD_PINMUX_MODE, PAD_IS_PWRON, PAD_PULL_UP, PAD_OUT_DISABLE, PAD_OUT_HIGH);

Pad_Dedicated_Config(LCDC_RGB_WRCLK, ENABLE);
Pad_Dedicated_Config(LCDC_HSYNC, ENABLE);
Pad_Dedicated_Config(LCDC_VSYNC, ENABLE);
Pad_Dedicated_Config(LCDC_CSN_DE, ENABLE);

Determine input and output color format, and select EDPI interface.

LCDC_InitTypeDef lcdc_init = {0};
lcdc_init.LCDC_Interface = LCDC_IF_DPI;
lcdc_init.LCDC_PixelInputFormat = LCDC_INPUT_RGB565;
lcdc_init.LCDC_PixelOutputFormat = LCDC_OUTPUT_RGB888;
lcdc_init.LCDC_PixelBitSwap = LCDC_SWAP_BYPASS; //lcdc_handler_cfg->LCDC_TeEn = LCDC_TE_DISABLE;
lcdc_init.LCDC_GroupSel = 1;

lcdc_init.LCDC_DmaThreshold =
    112;    //only support threshold = 8 for DMA MSIZE = 8; the other threshold setting will be support later
lcdc_init.LCDC_InfiniteModeEn = 1;
LCDC_Init(&lcdc_init);

Initialize EDPI interface, including clock division and other signal parameters, such as back porch signal.

uint32_t HSA = 48, HFP = 40, HBP = 40, HACT = EK9716_800480_LCD_WIDTH;
uint32_t VSA = 1, VFP = 13, VBP = 31, VACT = EK9716_800480_LCD_HEIGHT;

LCDC_eDPICfgTypeDef eDPICfg;//480*640  ---->   500 * 660
eDPICfg.eDPI_ClockDiv = 4;

eDPICfg.eDPI_HoriSyncWidth = HSA;
eDPICfg.eDPI_VeriSyncHeight = VSA;
eDPICfg.eDPI_AccumulatedHBP = HSA + HBP;
eDPICfg.eDPI_AccumulatedVBP = VSA + VBP;
eDPICfg.eDPI_AccumulatedActiveW = HSA + HBP + HACT;
eDPICfg.eDPI_AccumulatedActiveH = VSA + VBP + VACT;
eDPICfg.eDPI_TotalWidth = HSA + HBP + HACT + HFP;
eDPICfg.eDPI_TotalHeight = VSA + VBP + VACT + VFP;
eDPICfg.eDPI_HoriSyncPolarity = 0;
eDPICfg.eDPI_VeriSyncPolarity = 0;
eDPICfg.eDPI_DataEnPolarity = 1;
eDPICfg.eDPI_LineIntMask = 1;
eDPICfg.eDPI_ColorMap = EDPI_PIXELFORMAT_RGB888;//for RGB888
eDPICfg.eDPI_OperateMode = 0;//video mode
eDPICfg.eDPI_LcdArc = 0;
eDPICfg.eDPI_ShutdnPolarity = 0;
eDPICfg.eDPI_ColorModePolarity = 0;
eDPICfg.eDPI_ShutdnEn = 0;
eDPICfg.eDPI_ColorModeEn = 0;
eDPICfg.eDPI_UpdateCfgEn = 0;
eDPICfg.eDPI_TearReq = 0;
eDPICfg.eDPI_Halt = 0;
eDPICfg.eDPI_CmdMaxLatency = 0;//todo
eDPICfg.eDPI_LineBufferPixelThreshold = eDPICfg.eDPI_TotalWidth / 2;

EDPI_Init(&eDPICfg);

Control Reset pin to finish reset procedure.

ek9716_reset_high();
platform_delay_ms(200);
ek9716_reset_low();
platform_delay_ms(200);
ek9716_reset_high();
platform_delay_ms(200);

Functional Implementation

Use function rtk_lcd_hal_update_framebuffer() to assign specified buffer to screen.

Troubleshooting

Unexpected Color

Check input and output formats are set correctly.
Check color table corresponds to screen configuration.

Screen Flashes

Check the buffer that is being written into is not the same one that the screen uses to display.