Build our own ESP32 framework

[dkerr64]

The size of our binary is creeping up. With addition of vehicle occupancy the binary is now over 90% of available space.

So I investigated whether we can tell Arduino / ESP not to compile pieces we don't use... in other words use menuconfig to configure what components we want. It turns out that Arduino framework defaults to a pre-compiled default ESP32 framework. To change that we can add a sdkconfig.defaults file and make minor tweaks to platform.ini. There is an example here.

I have tried this and modified the example sdkconfig to this...

CONFIG_AUTOSTART_ARDUINO=y
# CONFIG_WS2812_LED_ENABLE is not set
CONFIG_FREERTOS_HZ=1000
CONFIG_MBEDTLS_PSK_MODES=y
CONFIG_MBEDTLS_KEY_EXCHANGE_PSK=y
CONFIG_ESP_COREDUMP_ENABLE_TO_FLASH=y
CONFIG_ESP_HTTPS_SERVER_ENABLE=n
CONFIG_ESP_HTTP_CLIENT_ENABLE_HTTPS=n
CONFIG_ESP_INSIGHTS_TRANSPORT_HTTPS=n
CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
CONFIG_LOG_COLORS=n
CONFIG_LOG_DEFAULT_LEVEL_NONE=y

and platformio.ini to include...

board_build.embed_txtfiles =
    managed_components/espressif__esp_insights/server_certs/https_server.crt
    managed_components/espressif__esp_rainmaker/server_certs/rmaker_mqtt_server.crt
    managed_components/espressif__esp_rainmaker/server_certs/rmaker_claim_service_server.crt
    managed_components/espressif__esp_rainmaker/server_certs/rmaker_ota_server.crt

and

framework = arduino, espidf

The result of this is binary reduced by about 6% to just under 85% of available flash.

The downside to this is that builds take significantly longer, even incremental builds.

[PaulWieland]

I wonder what makes this firmware so bloated... the ESP Home disco firmware is only 1.1MB.

[dkerr64]

I have added the necessary changes to PR #16 but it is not enabled because it adds considerable time to the builds.

In addition to the space savings, we can also enable CONFIG_FREERTOS_USE_TRACE_FACILITY which gives us the ability to monitor FreeRTOS task memory usage. But that is niche so leave disabled.