instruction for solving issue with this error : " AttributeError: module 'em' has no attribute 'BUFFERED_OPT' when building firmware for esp32 on udp transfering

Issue template

• Hardware description: esp32
• RTOS: freeRtos
• Installation type: micro_ros_setup
• Version or commit hash: version of micro-ROS used: galactic for Ubuntu 20.04

Steps to reproduce the issue

Assuming you have already setup the firmware using ros2 run micro_ros_setup create_firmware_ws.sh freertos esp32 and after proper wifi configuration, when you try to build the firmware for udp transferring using ros2 run micro_ros_setup build_firmware.sh you will most likely get an error which related to the Python environment and the em (Empy) module. The specific error is:

   AttributeError: module 'em' has no attribute 'BUFFERED_OPT'

To resolve this issue, follow these steps:

1. First, deactivate any active Python virtual environments:

   deactivate

To install empy in the specific Python environment used by the build process, you should use the pip associated with that Python installation. Here's the command to install empy version 3.3.4 in that environment:

~/microros_ws/firmware/toolchain/espressif/python_env/idf4.1_py3.8_env/bin/pip3 install empy==3.3.4

2. After that, verify the installation:

~/microros_ws/firmware/toolchain/espressif/python_env/idf4.1_py3.8_env/bin/python3 -c "import em; print(em.__file__)"

3. Update setuptools and wheel:

~/microros_ws/firmware/toolchain/espressif/python_env/idf4.1_py3.8_env/bin/pip3 install --upgrade setuptools wheel

5. Clean your micro-ROS workspace:

cd ~/microros_ws
rm -rf build install log

6. Rebuild the workspace:

colcon build --symlink-install

7. Source the setup file:

source install/local_setup.bash

8. Try building the firmware again:

ros2 run micro_ros_setup build_firmware.sh

從回報的 ros2 run micro_ros_setup build_firmware.sh 失敗以及位於 firmware/toolchain/espressif/python_env/idf4.1_py3.8_env 的 ESP32 Python 環境開始。確認 em.BUFFERED_OPT 錯誤和列出的 Empy 安裝步驟，然後判斷應在哪裡記錄此替代方案；完成的標準是韌體建置說明清楚涵蓋該錯誤及復原方法。