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Screen Parameter Usage Guide

REVISION HISTORY

Revision No.
Description
 Date
1.0
  • Initial release
    		•  02/22/2024

    1. Basic Introduction

    1.1 Overview

    As the name suggests, screen parameters refer to the parameter configurations used by the screen. This document mainly explains the configuration of point screen, the meaning of screen parameters, and how to set the correct screen parameters.

    1.2. Keyword Description

    • TTL/BT656

      TTL Transistor-Transistor Logic, The interface signal is a digital signal that transmits parallel RGB data.

      BT656 The interface signal is a digital signal that transmits YUV data.

    2. Screen Parameter Configuration File

    2.1 Screen Parameter Configuration File Path

    project\board\$(chip)\$(boardname)\config\config_disp.json

    2.2 Screen Parameter Configuration File Composition

    During the system startup process, the screen parameter configuration file will be parsed, and then different screen parameters will be saved in the system for use by the display module. The display module will obtain the required screen parameters from the system according to the parameter settings of the user calling the API. Please refer to the following for the process of obtaining screen parameters:MI_DISP_API

    The composition of the screen parameter configuration file is shown in the following figure. mi_disp is the root node, which contains three child nodes: content, screen parameters and PQ.

    The content node is a collection of screen parameter name lists, including two sub-nodes: m_pnlList and m_btList.

    • m_pnlList

      m_pnlList lists the screen parameter names of each interface type. User-defined screen parameters can be placed here, but one interface type can only correspond to one screen parameter. If the same type exists, only the first screen parameter will be selected.

    • m_btList

      m_btList lists the screen parameter names of BT656 in multiple resolutions.

    The screen parameters are composed of section and variable name:

    The section refers to the screen parameter name in the figure, EX: "SAT070AT50H18BH".

    The variable name refers to the field on the left side of ":", and the right side is the value assigned to the variable name.

    The section is unique and do not allow duplicate names, but variable names are allowed. As shown in the figure above, there can only be one section SAT070AT50H18BH, but m_pPanelName can be in different sections. The system distinguishes variable names according to different sections, and then adds different screen parameters.

    3. Add Screen Parameters

    1. The section name of the newly added screen parameter definition is not allowed to be the same as the existing section name

    2. Newly added screen parameters can be placed in front of m_pnlList (only the first panel of the same type is valid). If there are screen parameters of the same interface type as the newly added screen parameters in m_pnlList, the original screen parameters of the same interface type can be deleted, or the newly added screen parameters can be added before the original interface screen parameters.

    3. The following shows an example of adding new screen parameters in the screen parameter node:

      "SAT070AT50H18BH": {
                        "m_wPanelDispPath":       0,
                        "m_pPanelName": "SAT070AT50H18BH",
                        "m_ePanelTiming":         52,
                        "m_ePanelIntfType":       9,
                        "m_wPanelHSyncWidth":     48,
                        "m_wPanelHSyncBackPorch": 46,
                        "m_wPanelVSyncWidth":     4,
                        "m_wPanelVBackPorch":     23,
                        "m_wPanelHStart":         98,
                        "m_wPanelVStart":         27,
                        "m_wPanelWidth":          1024,
                        "m_wPanelHeight":         600,
                        "m_wPanelHTotal":         1344,
                        "m_wPanelVTotal":         635,
                        "m_wPanelDCLK":           51000000,
                        "m_bPanelInvDCLK":        0,
                        "m_bPanelInvDE":          0,
                        "m_bPanelInvHSync":       0,
                        "m_bPanelInvVSync":       0,
                        "m_wSpreadSpectrumFreq":  0,
                        "m_wSpreadSpectrumRatio": 0,
                        "m_ucPanelSwapChnR":      3,
                        "m_ucPanelSwapChnG":      2,
                        "m_ucPanelSwapChnB":      1,
                        "m_ucPanelSwapRgbML":     0
                },

    4. Screen Parameter Description

    4.1 Public Parameters

    Parameters Description
    m_pPanelName panel name
    m_ePanelTiming Output resolution, 52 means user-defined
    m_ePanelIntfType Interface type
    BT656: 3
    TTL: 9
    m_wPanelHSyncWidth Line synchronization signal pulse width
    m_wPanelHSyncBackPorch Horizontal synchronization signal back porch
    m_wPanelVSyncWidth Vertical synchronization signal pulse width
    m_wPanelVBackPorch Vertical synchronization signal back porch
    m_wPanelHStart m_wPanelHSyncWidth+m_wPanelHSyncBackPorch
    m_wPanelVStart m_wPanelVSyncWidth+m_wPanelVBackPorch
    m_wPanelWidth Number of effective pixels in horizontal direction
    m_wPanelHeight Number of effective pixels in vertical direction
    m_wPanelHTotal m_wPanelWidth+m_wPanelHSyncWidth+m_wPanelHSyncBackPorch+HsyncFrontPorch
    m_wPanelVTotal m_wPanelHeight+m_wPanelVSyncWidth+m_wPanelVBackPorch+VsyncFrontPorch
    m_wPanelDCLK pixel clk: m_wPanelHTotal * m_wPanelVTotal * fps
    m_bPanelInvDCLK pixel clk polarity inversion
    m_bPanelInvHSync Hsync polarity inversion
    m_bPanelInvVSync Vsync polarity inversion
    m_wSpreadSpectrumFreq Clock spread spectrum frequency modulation (for details, seespreadSpectrumFreqCalculation)
    m_wSpreadSpectrumRatio Clock spread spectrum ratio modulation (for details, seespreadSpectrumFreqCalculation)
    m_ucPanelSwapChnR Swap channel R
    default = 0(Maintain the original connection of the physical circuit, that is, the R channel uses the corresponding signal source in the hardware design)
    1: select R(Forcefully cover the channel signal source and replace the R-channel data with the R-channel signal output by the main control)
    2: select G
    3: select B
    m_ucPanelSwapChnG Swap channel G
    default = 0
    1: select R
    2: select G
    3: select B
    m_ucPanelSwapChnB Swap channel B
    default = 0
    1: select R
    2: select G
    3: select B
    m_ucPanelSwapRgbML Swap RGB MSB/LSB
    0: disable M/L swap
    1: enable M/L swap
    m_ePanelRgbDataType RGB data type or LCD data bus
    0:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB888,
    1:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB666,
    2:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB565,
    3:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB444,
    4:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB333,
    5:E_MI_DISP_MHALPNL_RGB_DTYPE_RGB332,
    6:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR888,
    7:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR666,
    8:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR565,
    9:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR444,
    10:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR333,
    11:E_MI_DISP_MHALPNL_RGB_DTYPE_BGR332,
    12:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_UY0VY1,
    13:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_VY0UY1,
    14:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_UY1VY0,
    15:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_VY1UY0,
    16:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_Y0UY1V,
    17:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_Y0VY1U,
    18:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_Y1UY0V,
    19:E_MI_DISP_MHALPNL_RGB_DTYPE_YUV422_Y1VY0U
    m_ePanelRgbDeltaOddMode delta mode Odd Field Data Arrangement
    0: RGB
    1: RBG
    2: GRB
    3: GBR
    4: BRG
    5: BGR
    m_ePanelRgbDeltaEvenMode delta mode Arrangement of Even Field Data
    0: RGB
    1: RBG
    2: GRB
    3: GBR
    4: BRG
    5: BGR
    m_ePanelRgbDataSwap RGB data swap for all data
    0: disable
    1: enable
    m_wPadDrvngLvl Pin drive strength adjustment. Set the drive strength level for all pins of the interface. There are 4 levels in total.
    0: 4mA
    1: 8mA
    2: 12mA
    3: 16mA

    Note: 12~13 of m_ePanelRgbDataType are optional for BT interface.m_ucPanelSwapRgbML is used to exchange the high and low bits of RGB data transmission, while m_ePanelRgbDataSwap is used to exchange all RGB data.

    Schematic diagram of normal timing for m_bPanelInvDCLK, m_bPanelInvHSync and m_bPanelInvVSync:

    Schematic diagram of enabling polarity reversal timing for m_bPanelInvDCLK, m_bPanelInvHSync and m_bPanelInvVSync:

    5. Correct Configuration of Screen Parameters

    To configure the screen parameters correctly, in addition to referring to the table attached to the above list, you also need to adjust the corresponding parameters according to the screen specifications or protocol specifications.

    5.1 Screen Specifications

    The Timing related section can be found in the specifications of most screen chips, as shown in the figure below. If you cannot find this information, please consult with the manufacturer.

    Parameters Descriptions
    m_wPanelVSyncWidth Horizontal Sync. Width
    m_wPanelHSyncBackPorch Horizontal Sync. Back Porch
    m_wPanelVSyncWidth Vertical Sync. Width
    m_wPanelVBackPorch Vertical Sync. Back Porch
    m_wPanelHStart m_wPanelHSyncWidth+m_wPanelHSyncBackPorch
    m_wPanelVStart m_wPanelVSyncWidth+m_wPanelVBackPorch
    m_wPanelWidth 240 (H)
    m_wPanelHeight 320 (V)
    m_wPanelHTotal m_wPanelHStart+m_wPanelWidth + hfp
    m_wPanelVTotal m_wPanelVStart+m_wPanelHeight + vfp