Memfault Zephyr + ESP32 Example

This sample app is based on the Zephyr samples/net/wifi example. It demonstrates a Zephyr + ESP32 integration with the Memfault SDK. It has been tested on the following boards:

• esp32c3_devkitm (default board)
• esp32s3_devkitm

Getting Started

The Memfault Zephyr integration guide is an excellent reference, and documents how the Memfault SDK was added to the base example app:

https://docs.memfault.com/docs/mcu/zephyr-guide

To try out this example app:

1. Set up the Zephyr prerequisites: https://docs.zephyrproject.org/latest/develop/getting_started/index.html

2. Create a zephyr workspace and set it up with this project:

   mkdir zephyr-workspace
   cd zephyr-workspace
   west init -m https://github.com/memfault/zephyr-esp32-example
   west update

3. Build the example app:

   west build zephyr-esp32-example --sysbuild

   --sysbuild will build the MCUboot image as well, which will also get flashed in the following step. To run sysbuild by default, you can configure your workspace with west config --local build.sysbuild True.

4. Flash the example app:

    west flash

5. Open a serial console and interact with the sample app shell. For example using PySerial:

   # select the correct serial port for your system
   pyserial-miniterm --raw /dev/serial/by-id/usb-Silicon_Labs_CP2102N_USB_to_UART_Bridge_Controller_1cd857b4d5a0eb11bf35cdacdf749906-if00-port0 115200
   
   uart:~$ mflt get_device_info
   [00:09:21.911,000] <inf> mflt: S/N: DEMOSERIAL
   [00:09:21.911,000] <inf> mflt: SW type: zephyr-app
   [00:09:21.911,000] <inf> mflt: SW version: 0.0.1727a85c
   [00:09:21.911,000] <inf> mflt: HW version: esp32c3_devkitm
   
   # connect wifi
   uart:~$ wifi connect <ssid> <pw>
   
   # test memfault export over uart
   uart:~$ mflt export
   MC:CAKnAgIDAQpqemVwaHlyLWFwcAltMS4wLjArZDU5MmRhOAZvZXNwMzJjM19kZXZraXRtC0Z1sxH2/usEogEABQAISg==:

Testing OTA

The payload to upload to Memfault is:

build/zephyr-esp32-example/zephyr/zephyr.signed.confirmed.bin

This file is set as "confirmed", so it won't revert after 1 boot cycle (not safe against bootloops!). See the Zephyr documentation for details.

Follow the normal Memfault OTA workflow:

1. build and flash an image with a version like 0.0.1 (see the VERSION file for setting an application version).
2. rebuild with a newer version, 0.0.2
3. upload the zephyr.signed.confirmed.bin file to a Memfault Release named 0.0.2.
4. deploy the 0.0.2 release to the cohort with the device (default unless changed)
5. on the device shell, connect wifi with wifi connect <ssid> <pw>, and trigger the OTA with mflt get_latest_release
6. when the device reboots, confirm the new version is set with mflt get_device_info

Note

If this error occurs when applying the new image:

[00:10:07.255,000] <dbg> mflt: memfault_platform_log: Error requesting upgrade, rv=-14
[00:10:07.260,000] <err> mflt: Error upgrading firmware, rv=-1

It may be necessary to run mcuboot erase 2 one time before running the test, to wipe the secondary slot so it's ready to receive the new image.