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ESP8266 RTOS Integration Guide


In this guide we will walk through the steps for integrating the Memfault Firmware SDK into a project using the ESP8266 RTOS SDK. The integration has been tested against the v3.3 release.

Upon completion of the integration, the following subcomponents will be added to your system!

Integration Steps#


This tutorial assumes you have a working ESP8266 RTOS SDK environment and are able to flash a board supported by the SDK.

Add memfault-firmware-sdk and prepare port#

You will first need to add the memfault-firmware-sdk to your projects.

$ mkdir -p components/memfault_port/config
$ echo $'COMPONENT_ADD_INCLUDEDIRS := config\n' > components/memfault_port/
$ touch components/memfault_port/memfault_port.c
$ touch components/memfault_port/config/memfault_platform_config.h
$ touch components/memfault_port/config/memfault_metrics_heartbeat_config.def
$ touch components/memfault_port/config/memfault_trace_reason_user_config.def
$ git submodule add \

When done, you should see the following directory structure:

โ”œโ”€โ”€ config
โ”‚ โ”œโ”€โ”€ memfault_platform_config.h
โ”‚ โ”œโ”€โ”€ memfault_metrics_heartbeat_config.def
โ”‚ โ””โ”€โ”€ memfault_trace_reason_user_config.def
โ”œโ”€โ”€ memfault-firmware-sdk
โ””โ”€โ”€ memfault_port.c

Add EXTRA_COMPONENT_DIRS to Project Makefile#

First, update the Makefile for your project to pick up the Memfault ESP8266 port

diff --git a/Makefile b/Makefile
index 952298b..d97ce01 100644
--- a/Makefile
+++ b/Makefile
@@ -5,5 +5,8 @@
+ components/memfault_port/memfault-firmware-sdk/ports/esp8266_sdk/memfault \
+ components/memfault_port/memfault-firmware-sdk/ports/esp8266_sdk/memfault_freertos
include $(IDF_PATH)/make/

Apply Patches to ESP8266 RTOS SDK#

There are two small updates to make to the ESP8266 RTOS SDK. These can be added using git apply:

$ cd ${IDF_PATH}
$ git apply ${MEMFAULT_FIRMWARE_SDK}/ports/esp8266_sdk/esp8266_v33_rtos.patch

The patch does two things:

  • Installs a facility to capture RTOS task creation
  • Adds a unique identifier to image so Memfault can perform accurate stack unwinds
diff --git a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
index 080ce65c..cca3a354 100644
--- a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
+++ b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
@@ -31,6 +31,11 @@
#include "sdkconfig.h"
+#include "memfault/ports/freertos_trace.h"
+#define INCLUDE_xTaskGetHandle 1
#ifndef __ASSEMBLER__
#include <stdlib.h>
#include "rom/ets_sys.h"
diff --git a/make/ b/make/
index c06835b2..681db825 100644
--- a/make/
+++ b/make/
@@ -508,7 +508,12 @@ COMPONENT_LINKER_DEPS ?=
$(summary) LD $(patsubst $(PWD)/%,%,$@)
$(CC) $(LDFLAGS) -o $@ -Wl,-Map=$(APP_MAP)
+ $(summary) Adding Unique Build Id
+ $(PYTHON) $(PROJECT_PATH)/components/memfault_port/memfault-firmware-sdk/scripts/ $@
app: $(APP_BIN) partition_table_get_info
ifeq ("$(CONFIG_SECURE_BOOT_ENABLED)$(CONFIG_SECURE_BOOT_BUILD_SIGNED_BINARIES)","y") # secure boot enabled, but remote sign app image
@echo "App built but not signed. Signing step via"

Create a Project and get a Project Key

Go to and from the "Select A Project" dropdown, click on "Create Project" to setup your first project such as "smart-sink-dev".

Once you've created your project, you'll be automatically taken to an integration guide which includes your project key. Copy it to follow the rest of the guide.

Implement Platform Dependencies#

In order to save traces, you will need to implement a dependency function that tells memfault version information. You can copy the following template into the memfault_port.c file created in the first step:


Be sure to fill in the appropriate.

//! @file components/memfault_port/memfault_port.c
#include "memfault/components.h"
#include <stdio.h>
#include "memfault/esp8266_port/core.h"
sMfltHttpClientConfig g_mflt_http_client_config = {
.api_key = "YOUR_PROJECT_KEY",
static char s_fw_version[32];
void memfault_platform_get_device_info(sMemfaultDeviceInfo *info) {
if (s_fw_version[0] == 0) {
// initialize version
char build_id[7];
memfault_build_id_get_string(build_id, sizeof(build_id));
snprintf(s_fw_version, sizeof(s_fw_version), "1.0.0+%s", build_id);
// platform specific version information. For more details
// see
*info = (sMemfaultDeviceInfo) {
.device_serial = "DEMOSERIAL",
.software_type = "app-fw",
.software_version = s_fw_version,
.hardware_version = "dvt",
int memfault_platform_boot(void) {
return 0;

Initialize the Memfault platform from app_main()#

Add a call to memfault_platform_boot() from your app_main()

//! your_project_main.c
#include "memfault/components.h"
// ...
void app_main()
// ...

Periodically post data to Memfault#

From a background task, periodically try sending data to Memfault when the device is connected to WiFi by calling #include "memfault/esp8266_port/http_client.h". This routine will issue an HTTPS request if and only if there is new Memfault data to send.

#include "memfault/esp8266_port/http_client.h"
void your_background_task(void) {

For testing, you can also force a post immediately by using the mflt post_chunks CLI command

Force a Crash and Upload to Memfault#

Example crashes can be generated using the crash CLI:

esp8266> crash
Saving Memfault Coredump!
I (340) mflt: Memfault Build ID: 134cc1627c9a84c36bdba206b6d96940b6aae698
I (362) mflt: Coredumps will be saved at 0x110000 (524288B)
I (366) mflt: ESP Reset Cause 0x7
I (369) mflt: Reset Causes:
This is an example of ESP-IDF console component.
Type 'help' to get the list of commands.
Use UP/DOWN arrows to navigate through command history.
Press TAB when typing command name to auto-complete.
esp8266> join <your_network> <your_network_password>
esp8266> post_chunks
D (24436) mflt: Posting Memfault Data
D (27019) mflt: Posting Memfault Data Complete!
I (27023) mflt: Result: 0

Test Tip#

Data can also also be dumped out over the CLI using the mflt export_data CLI command.

esp8266> export_data
I (57880) mflt: MC:CAKmAgEDAQpmYXBwLWZ3CWwxLjAuMCsxMzRjYzEGY2R2dAShAYUZ00oAAAAAG4c=:

The CLI output can then be saved to a file and the "chunk" data can be posted to the Memfault Cloud using the Memfault CLI tool:

$ memfault --project-key ${YOUR_PROJECT_KEY} post-chunk --encoding sdk_data_export cli-output.txt
Found 2 Chunks. Sending Data ...

Upload Symbol File#

At this point you should be able to generate a test trace event and push it to the Memfault UI. You can confirm the issue has arrived succesfully by navigating to the "Issues" page. Follow the link pointed to below and upload a symbol file.

After this step you will see the trace in the list of issues!


You can programatically upload symbol files with the Memfault CLI tool.

Troubleshooting Data Transfer#

If you run into any issues with your data transfer implementation, we have tools to help!