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ESP32 Soft-IPM example

Overview

This simple example can be used with multicore ESP32 Soc, and demonstrates the software intercore messaging mechanism to be used in AMP applications.

ESP32 has two CPU named APP and PRO, in this simple example PRO send a message to the APP using the IPM driver, and waits for the APP response message and prints its contents on console.

ESP32 intercore messaging has up two four channels, the 0 and 1 are reserved for BT and WIFI messages, and channels 2 and 3 is free to any application, each channel supports up to 64 bytes of data per message, so high level protocol is responsible to fragment larger messages in chunks of 64bytes.

Building and Running the Zephyr Code

The sample requires two build commands to run, for that reason a pre built version of esp32_net, the APP cpu side firmware is already provided for quick tests just type on the console:

west build -b esp32 samples/drivers/ipm/ipm_esp32
west flash

The other option is building from scratch just involve a single extra build command and file moving, first of all you need to build the esp32_net firmware as follows:

west build -b esp32_net samples/drivers/ipm/ipm_esp32/ipm_esp32_net

Copy output file build/zephyr/esp32_net_firmware.c to samples/drivers/ipm/ipm_esp32/src, then build the main project and flash as stated earlier, and you would see the following output:

*** Booting Zephyr OS build zephyr-v3.0.0-1911-g610f489c861e  ***
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
PRO_CPU is sending a fake request, waiting remote response...
PRO_CPU received a message from APP_CPU : APP_CPU: This is a response