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:

• esp32s3_devkitm/esp32s3/procpu (default board)
• esp32c3_devkitm*

* _NOTE: Currently does not have support for data upload. Export chunks to memfault with mflt export and upload via the chunks debug log.

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 -s "<ssid>" -k <key type> -p "<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.