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boards: shields: add ST MB1835 shield
Add support for the ST MB1835 2.47-inch round DSI TFT-LCD daughter board designed for STM32 Discovery kits. Signed-off-by: Charles Dias <[email protected]>
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‎boards/shields/st_lcd_dsi_mb1835/Kconfig.defconfig‎

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# Copyright (c) 2025 Charles Dias
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# SPDX-License-Identifier: Apache-2.0
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if SHIELD_ST_LCD_DSI_MB1835
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orsource "boards/*.defconfig"
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if LVGL
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config LV_Z_BITS_PER_PIXEL
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default 32
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config LV_Z_FLUSH_THREAD
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default y
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choice LV_COLOR_DEPTH
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default LV_COLOR_DEPTH_32
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endchoice
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endif # LVGL
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endif # SHIELD_ST_LCD_DSI_MB1835

‎boards/shields/st_lcd_dsi_mb1835/Kconfig.shield‎

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# Copyright (c) 2025 Charles Dias
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# SPDX-License-Identifier: Apache-2.0
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config SHIELD_ST_LCD_DSI_MB1835
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def_bool $(shields_list_contains,st_lcd_dsi_mb1835)

‎boards/shields/st_lcd_dsi_mb1835/boards/stm32u5g9j_dk1.conf‎

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# Heap memory pool configuration
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CONFIG_HEAP_MEM_POOL_SIZE=65536
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# Display configuration
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CONFIG_STM32_LTDC_ARGB8888=y
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CONFIG_DISPLAY_HX8379C_INIT_PRIORITY=87

‎boards/shields/st_lcd_dsi_mb1835/doc/index.rst‎

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.. _st_lcd_dsi_mb1835:
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ST LCD DSI MB1835
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#################
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Overview
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********
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The MB1835 shield (revision B-01) provides a 2.47-inch round TFT-LCD with MIPI DSI interface
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and capacitive touch screen, specifically designed for STM32U5G9J-DK1 Discovery kit.
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The shield features:
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- 2.47-inch round TFT-LCD with 480x480 pixel resolution
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- 16.7M color depth (RGB888)
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- J025F1CN0201W display module with Himax HX8379C LCD controller
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- MIPI DSI |reg| 2-data lane interface
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- Capacitive touch panel (CTP)
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- LED backlight with GPIO control
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.. figure:: mb1835_front.webp
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:alt: MB1835 Display shield front image
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:align: center
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MB1835 Display Shield Front Image
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.. figure:: mb1835_back.webp
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:alt: MB1835 Display shield back image
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:align: center
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MB1835 Display Shield Back Image
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The MB1835 display board connects to the STM32U5G9J-DK1 through the CN1 connector:
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+------+--------------+------------+-------+--------------+-----------------+
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| CN1 | Description | Interface | CN1 | Description | Interface |
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| odd | | | even | | |
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+======+==============+============+=======+==============+=================+
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| 1 | GND | - | 2 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 3 | DSI_CK_P | DSI | 4 | TOUCH_INT | Interrupt out |
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+------+--------------+------------+-------+--------------+-----------------+
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| 5 | DSI_CK_N | DSI | 6 | GND | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 7 | GND | - | 8 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 9 | DSI_D0_P | DSI | 10 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 11 | DSI_D0_N | DSI | 12 | GND | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 13 | GND | - | 14 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 15 | DSI_D1_P | DSI | 16 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 17 | DSI_D1_N | DSI | 18 | GND | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 19 | GND | - | 20 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 21 | BLVDD(+5V) | - | 22 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 23 | BLVDD(+5V) | - | 24 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 25 | - | - | 26 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 27 | BLGND | - | 28 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 29 | BLGND | - | 30 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 31 | - | - | 32 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 33 | - | - | 34 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 35 | - | - | 36 | 3.3V | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 37 | - | - | 38 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 39 | - | - | 40 | I2C_SDA | I2C |
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+------+--------------+------------+-------+--------------+-----------------+
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| 41 | - | - | 42 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 43 | - | - | 44 | I2C_SCL | I2C |
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+------+--------------+------------+-------+--------------+-----------------+
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| 45 | - | - | 46 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 47 | - | - | 48 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 49 | DSI_TE | DSI | 50 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 51 | - | - | 52 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 53 | BL_CTRL | GPIO | 54 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 55 | - | - | 56 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 57 | RESET | GPIO | 58 | - | - |
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+------+--------------+------------+-------+--------------+-----------------+
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| 59 | - | - | 60 | 1.8V | - |
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+------+--------------+------------+-------+--------------+-----------------+
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Requirements
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************
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Your board needs to have a ``mipi_dsi`` device tree label to work with this shield.
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Usage
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*****
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The shield can be used in any application by setting ``SHIELD`` to
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``st_lcd_dsi_mb1835`` and adding the necessary device tree properties.
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Set ``--shield "st_lcd_dsi_mb1835"`` when you invoke ``west build``. For example:
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.. zephyr-app-commands::
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:zephyr-app: samples/drivers/display
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:board: stm32u5g9j_dk1
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:shield: st_lcd_dsi_mb1835
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:goals: build
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References
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**********
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- `STM32U5G9J-DK1 User Manual <https://www.st.com/resource/en/user_manual/um2967-discovery-kits-with-stm32u5x9nj-mcus-stmicroelectronics.pdf>`_
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- `MB1835 Schematic (Rev B-01) <https://www.st.com/resource/en/schematic_pack/mb1835-vdd1v8-b01-schematic.pdf>`_

‎boards/shields/st_lcd_dsi_mb1835/doc/mb1835_back.webp‎

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‎boards/shields/st_lcd_dsi_mb1835/doc/mb1835_front.webp‎

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‎boards/shields/st_lcd_dsi_mb1835/shield.yml‎

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shields:
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- name: st_lcd_dsi_mb1835
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full_name: ST LCD DSI MB1835
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vendor: st
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supported_features:
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- display

‎boards/shields/st_lcd_dsi_mb1835/st_lcd_dsi_mb1835.overlay‎

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/*
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* Copyright (c) 2025 Charles Dias
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/dt-bindings/display/panel.h>
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#include <zephyr/dt-bindings/mipi_dsi/mipi_dsi.h>
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/ {
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chosen {
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zephyr,display = &zephyr_lcd_controller;
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};
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};
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&pll3 {
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div-m = <4>; /* Input divider: 16MHz / 4 = 4MHz */
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mul-n = <125>; /* Multiplier: 4MHz * 125 = 500MHz VCO */
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div-p = <8>; /* P output: 500MHz / 8 = 62.5MHz (for DSI clock lane) */
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div-q = <2>; /* Q output: 500MHz / 2 = 250MHz */
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div-r = <24>; /* R output: 500MHz / 24 = 20.83MHz (for LTDC pixel clock) */
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clocks = <&clk_hse>;
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status = "okay";
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};
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&zephyr_mipi_dsi {
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status = "okay";
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pll-ndiv = <125>; /* PLLDSINDIV = 125 */
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pll-idf = <4>; /* DSI_PLL_IN_DIV4 */
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pll-odf = <2>; /* DSI_PLL_OUT_DIV2 */
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pll-vco-range = <0x1>; /* DSI_DPHY_VCO_FRANGE_800MHZ_1GHZ */
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pll-charge-pump = <0x0>;/* DSI_PLL_CHARGE_PUMP_2000HZ_4400HZ */
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pll-tuning = <0x0>; /* DSI_PLL_LOOP_FILTER_2000HZ_4400HZ */
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phy-freq-range = <0x8>; /* DSI_DPHY_FRANGE_450MHZ_510MHZ */
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phy-low-power-offset = <0x0>; /* PHY_LP_OFFSSET_0_CLKP */
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hs-active-high;
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vs-active-high;
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de-active-high;
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largest-packet-size = <0>;
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host-timeouts = <1>, /* TimeoutCkdiv */
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<0>, /* HighSpeedTransmissionTimeout */
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<0>, /* LowPowerReceptionTimeout */
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<0>, /* HighSpeedReadTimeout */
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<0>, /* LowPowerReadTimeout */
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<0>, /* HighSpeedWriteTimeout */
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<0>, /* HighSpeedWritePrespMode */
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<0>, /* LowPowerWriteTimeout */
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<0>; /* BTATimeout */
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phy-timings = <11>, /* ClockLaneHS2LPTime */
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<40>, /* ClockLaneLP2HSTime */
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<12>, /* DataLaneHS2LPTime */
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<23>, /* DataLaneLP2HSTime */
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<0>, /* DataLaneMaxReadTime */
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<7>; /* StopWaitTime */
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hx8379c: hx8379c@0 {
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status = "okay";
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compatible = "himax,hx8379c";
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reg = <0x0>; /* Virtual channel 0 */
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width = <480>;
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height = <480>;
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data-lanes = <2>;
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pixel-format = <MIPI_DSI_PIXFMT_RGB888>;
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reset-gpios = <&dsi_lcd_qsh_030 57 GPIO_ACTIVE_HIGH>;
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display-timings {
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compatible = "zephyr,panel-timing";
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hsync-active = <1>;
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vsync-active = <1>;
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de-active = <0>;
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pixelclk-active = <0>;
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hsync-len = <2>;
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hback-porch = <1>;
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hfront-porch = <1>;
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vsync-len = <1>;
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vback-porch = <13>;
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vfront-porch = <50>;
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};
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};
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};
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&zephyr_lcd_controller {
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status = "okay";
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width = <480>;
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height = <480>;
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pixel-format = <PANEL_PIXEL_FORMAT_RGB_888>;
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bl-ctrl-gpios = <&dsi_lcd_qsh_030 53 GPIO_ACTIVE_HIGH>;
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def-back-color-red = <0>;
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def-back-color-green = <0>;
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def-back-color-blue = <0>;
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/* J025F1CN0201W display module */
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display-timings {
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compatible = "zephyr,panel-timing";
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hsync-active = <1>;
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vsync-active = <1>;
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de-active = <0>;
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pixelclk-active = <0>;
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hsync-len = <2>;
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hback-porch = <1>;
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hfront-porch = <1>;
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vsync-len = <1>;
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vback-porch = <13>;
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vfront-porch = <50>;
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};
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};

‎boards/st/stm32u5g9j_dk1/stm32u5g9j_dk1.dts‎

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};
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};
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dsi_lcd_qsh_030: connector_dsi_lcd {
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compatible = "st,dsi-lcd-qsh-030";
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#gpio-cells = <2>;
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gpio-map-mask = <0xffffffff 0xffffffc0>;
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gpio-map-pass-thru = <0 0x3f>;
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gpio-map = <4 0 &gpioe 8 0>, /* TOUCH_INT */
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<22 0 &gpiod 8 0>, /* SPI chip SEL */
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<24 0 &gpiob 13 0>, /* SPI CLK */
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<26 0 &gpiod 4 0>, /* SPI MOSI */
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<28 0 &gpiod 11 0>, /* SPI DCX */
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<35 0 &gpioe 5 0>, /* SCLK/MCLK */
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<37 0 &gpioe 4 0>, /* LRCLK */
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<40 0 &gpioh 4 0>, /* I2C5_SDA */
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<43 0 &gpioi 7 0>, /* SWIRE */
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<44 0 &gpioh 5 0>, /* I2C5_SCL */
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<49 0 &gpiof 11 0>, /* DSI_TE */
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<53 0 &gpioi 6 0>, /* LCD_BL_CTRL */
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<57 0 &gpiod 5 0>; /* DSI_RESET */
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};
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aliases {
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led0 = &green_led_0;
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led1 = &red_led_0;
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volt-sensor0 = &vref1;
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volt-sensor1 = &vbat4;
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};
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dsi_lcd_qsh_030: connector_dsi_lcd {
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compatible = "st,dsi-lcd-qsh-030";
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#gpio-cells = <2>;
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gpio-map-mask = <0xffffffff 0xffffffc0>;
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gpio-map-pass-thru = <0 0x3f>;
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gpio-map = <4 0 &gpioe 8 0>, /* TOUCH_INT */
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<40 0 &gpioh 4 0>, /* I2C5_SDA */
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<44 0 &gpioh 5 0>, /* I2C5_SCL */
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<53 0 &gpioi 6 0>, /* DSI_BL_CTRL */
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<57 0 &gpiod 5 0>; /* DSI_RESET */
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};
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};
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&clk_hsi48 {
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&vbat4 {
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status = "okay";
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};
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/* alias used by display shields */
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zephyr_mipi_dsi: &mipi_dsi {};
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/* alias used by LCD display shields */
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zephyr_lcd_controller: &ltdc {};

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