The previous post described how to setup ESP32 or ESP8266 module with ATECC508A crypto chip to use Google IoT Core. This post describes similar setup, but without the ECC508A crypto chip.



  • Set up Google IoT Core account
  • Follow the device manager guide to register your device and generate ES256 key pair
  • Two files will be created: ec_private.pem and ec_public.pem
  • Initialise the device:
mos flash esp8266       # Or esp32
mos wifi SSID PASS      # Your WiFi network name and password
  • Copy the private key to the device
mos put ec_private.pem
  • Configure the device's GCP settings

mos config-set mqtt.enable=true mqtt.ssl_ca_cert=ca.pem sntp.enable=true gcp.enable=true gcp.project=$PROJECT gcp.region=$REGION gcp.registry=$REGISTRY gcp.device=$DEVICE_ID$DEVICE_ID gcp.key=ec_private.pem debug.stderr_topic=/devices/$DEVICE_ID/events/log debug.stdout_topic=/devices/$DEVICE_ID/events/log


Run mos ui to enter Web UI. Specify your device address (serial port) to connect to your device and reboot it. You should see the following messages:

mgos_gcp_init        GCP client for my-project/us-central1/my-registry/my-es256-device, EC key in ec_private.pem
mgos_mqtt_ev         MQTT Connect (1)
mgos_mqtt_ev         MQTT CONNACK 0
mgos_mqtt_ev         Subscribing to 'my-es256-device/rpc'
mgos_mqtt_ev         Subscribing to 'my-es256-device/rpc/#'

Default firmware publishes an MQTT message whenever the "Flash" button is pressed:

Published: yes topic: /devices/my-es256-device/events message: {"free_ram":30080,"total_ram":51912} 

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