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commit 1267f78dcc51be3ccd8a28f8ea9c6c8dffe0d808 Author: Alan Carvalho de Assis <[email protected]> AuthorDate: Sun Aug 23 12:53:19 2026 -0300 doc/esp32s3: Update esp32s3-touch-lcd7 documentation This commit updates the board documentation. Signed-off-by: Alan C. Assis <[email protected]> Assisted-by: Claude Code --- .../esp32s3/boards/esp32s3-touch-lcd7/index.rst | 80 ++++++++++++++++++++++ 1 file changed, 80 insertions(+) diff --git a/Documentation/platforms/xtensa/esp32s3/boards/esp32s3-touch-lcd7/index.rst b/Documentation/platforms/xtensa/esp32s3/boards/esp32s3-touch-lcd7/index.rst index 8d9231c79f7..b0f50683332 100644 --- a/Documentation/platforms/xtensa/esp32s3/boards/esp32s3-touch-lcd7/index.rst +++ b/Documentation/platforms/xtensa/esp32s3/boards/esp32s3-touch-lcd7/index.rst @@ -78,6 +78,42 @@ The board has a 7-inch LCD: EXIO2 DISP Backlight enable pin ========= ======== ========================= +The panel is an EK9716 driven over a 16-bit parallel RGB565 bus by the +LCD_CAM peripheral. Its timing is: + + ==================== ======= + Parameter Value + ==================== ======= + Resolution 800x480 + Pixel clock 16 MHz + HSYNC pulse width 4 + HSYNC back porch 8 + HSYNC front porch 8 + VSYNC pulse width 4 + VSYNC back porch 8 + VSYNC front porch 8 + ==================== ======= + +The RGB bus takes most of the usable pins, so the panel reset and the +display enable are not wired to GPIOs. They hang off a CH422G I/O +expander, reached over the I2C bus shared with the touch controller: + + ========= ============ ================================== + Signal Connection Description + ========= ============ ================================== + SDA GPIO8 I2C data, expander and touch + SCL GPIO9 I2C clock, expander and touch + TP_RST CH422G EXIO1 GT911 touch controller reset + DISP CH422G EXIO2 Display and backlight enable + LCD_RST CH422G EXIO3 Panel reset + SD_CS CH422G EXIO4 TF card chip select + USB_SEL CH422G EXIO5 USB / CAN transceiver select + ========= ============ ================================== + +A 800x480 RGB565 framebuffer is 768000 bytes and does not fit in internal +RAM, so any configuration that drives the panel must also enable the +onboard 8MB octal PSRAM and leave it in the common heap. + Configurations ============== @@ -92,6 +128,50 @@ All of the configurations presented below can be tested by running the following Configuration Directories ------------------------- +lcd +--- + +Brings up the onboard 7 inch 800x480 panel as a framebuffer character +driver at ``/dev/fb0``, on top of the ``usbnsh`` console. The CH422G I/O +expander is used to take the panel out of reset and to switch the display +on once the framebuffer exists, and the PSRAM the framebuffer is allocated +from is enabled. + +Note that the console is on UART0, GPIO43 and GPIO44, reached through the +USB-to-UART bridge on the UART USB-C connector. It is deliberately not on +the native USB peripheral, because that is the connector a USB host +configuration drives. + +``apps/examples/fb`` is included to prove the panel out. It reports the +geometry of the framebuffer it found and then draws a series of nested +rectangles over the whole display:: + + nsh> fb + VideoInfo: + fmt: 11 + xres: 800 + yres: 480 + nplanes: 1 + PlaneInfo (plane 0): + fbmem: 0x3c050040 + fblen: 1536000 + stride: 1600 + display: 0 + bpp: 16 + Mapped FB: 0x3c050040 + Use consecutive fbmem2 = 0x3c10b840, yoffset = 480 + 0: ( 0, 0) (800,480) + 1: ( 72, 43) (656,394) + 2: (144, 86) (512,308) + 3: (216,129) (368,222) + 4: (288,172) (224,136) + 5: (360,215) ( 80, 50) + Test finished + +The framebuffer is in PSRAM, which is why ``fbmem`` is in the 0x3c000000 +range, and ``fblen`` is 1536000 rather than 768000 because the driver is +double buffered by default. + usbnsh ------
