AddOn Display In For PoE-P4 ESP-IDF Example Program Tutorial

This tutorial explains how to build the example program for using Unit PoE-P4 with AddOn Display In For PoE-P4. Users can perform secondary development based on this example.

1. Preparation

1. Environment setup: This tutorial is based on setting up the ESP-IDF development environment on Ubuntu. For instructions on setting up the build environment on other platforms, please refer to ESP-IDF - ESP32-P4 Getting Started Guide.

2. Use the git version control tool to clone the esp-idf project, switch to the specified branch, and run the script to install the required toolchains.

git clone -b v5.5.2 --recursive https://github.com/espressif/esp-idf.git
cd esp-idf
./install.sh esp32p4
. ./export.sh

3. In addition to Unit PoE-P4 and AddOn Display In For PoE-P4, this example also uses a 5.0-inch, 1280 x 720 resolution, 24P FPC ST7123 display assembly. If you use a different display, refer to Unit PoE-P4 MIPI DSI+TP+BL FPC Interface for interface details.

4. The idf.py commands used in the following steps depend on ESP-IDF. Before running the commands, call export.sh from ESP-IDF to activate the relevant environment variables. For details, please refer to ESP-IDF - ESP32-P4 Getting Started Guide.

2. Example Program

1. Download the example source code for using Unit PoE-P4 with AddOn Display In For PoE-P4, and extract it.

2. Enter the M5Unit-PoE-P4-AddOn-Display-In-Example project folder and call export.sh from the esp-idf project to activate the relevant environment variables. (Modify the command according to the actual esp-idf path.)

cd M5Unit-PoE-P4-AddOn-Display-In-Example
. ~/.espressif/v5.5.2/esp-idf/export.sh

3. Build and Flash

Connect Unit PoE-P4 to the computer using a data cable. Press and hold the reset button until the green indicator lights up, then release the button. The device will enter download mode and wait for firmware flashing.

Then execute the following commands to set the target chip and port (modify the last command as needed), build, and flash the program.

idf.py set-target esp32p4
idf.py build
idf.py -p /dev/ttyACM0 flash monitor

4. Getting Started

After flashing is complete, follow these steps to connect the devices and display the HDMI input image:

1. Disconnect power from Unit PoE-P4.
2. Connect AddOn Display In For PoE-P4 to the MIPI-CSI interface on Unit PoE-P4.
3. Use a 24P FPC cable to connect the ST7123 display assembly to the MIPI-DSI interface on Unit PoE-P4.
4. Connect the HDMI source to the HDMI input on AddOn Display In For PoE-P4. Check the FPC cable orientation and connector locks, then power Unit PoE-P4 after confirming that all connections are correct.
5. Set the actual output resolution signal to 1280 x 720 @ 60Hz.

• On Windows, using an Intel integrated GPU as an example, open Intel® Graphics Command Center (Beta) (if it is not installed, download it from the Microsoft Store), click Display, and configure the settings as shown below:

• On macOS, using a 2020 MacBook Pro as an example, download SwitchResX, open the application, click M5DisplayIn -> Current Resolutions, and select 1280 x 720 in the Resolution column:

6. After the settings are applied successfully, the display works normally on macOS. On Windows, confirm that the Active signal mode resolution appears as shown below.

This example uses LT6911D to convert the HDMI input signal into 2-Lane MIPI-CSI YUYV422 data, supporting two input resolutions: 1280 x 720 @ 60Hz and 1920 x 1080 @ 30Hz. ESP32-P4 configures the CSI controller according to the valid resolution and MIPI-CSI Lane rate detected by LT6911D, then writes complete image frames to PSRAM through CSI DMA. At 1280 x 720 @ 60Hz, the full image is displayed. At 1920 x 1080 @ 30Hz, a 1280 x 720 region is cropped from the center of the image without scaling. The program then uses both CPU cores to convert YUYV422 to BGR565, rotates the image 90° counterclockwise through PPA, and finally outputs it through 2-Lane MIPI-DSI to the 720 x 1280 ST7123P display. The actual CSI DMA capture frame rate is indicated by the Status: DMA=... (... FPS) serial log. The MIPI-DSI display scan refresh rate is independent of the HDMI input refresh rate.

• Windows

• macOS