ESP32Monitoring

Setup

Setup PlatformIO to program on a real editor

A new platformio project was created in the repo. I chose Espressif ESP32 Dev module as my board and Arduino as my development framework. The settings for this can be easily changed in the platformio.ini page.

Library Setup

The lib_deps field in platform.ini manages your imported libraries.

lib_deps=
    256dpi/MQTT @ ^2.5.2
    bblanchon/ArduinoJson @^7.0.4

You can set the exact versions as well as allowing for minor upgrades. These packages can be found in the PlatformIO Registry.

Set up AWS CDK to deploy your monitoring!

Create a src/config.h file from src/example_config in the eeprom_upload directory and paste Certs and other values to flash them into each ESP32 monitoring device.

You can find

AWS IOT Endpoint -> Settings (seems like you only have one endpoint per account?) AWS Root CA Certificate - get this from https://docs.aws.amazon.com/iot/latest/developerguide/server-authentication.html#server-authentication-certs AWS Device Private Key and Cert

• in Paramater Store
• or in the CDK deployment:
  • OutputCertPem -> Device Certificate
  • OutputPrivKey -> Device Private Key

Note! There are size limitations of the Preferences.h library. Only allows 15 characters for the keyname and 4000 characters for the value.

Note! We use cdk-iot-core-certificates to set up multiple Things and their certs in AWS. While this is powerful, it also gives each Thing really wide range authorization and there is no way to set a more fine-grained policies.

How the code works

cdk-iot-core-certificates

This is a L3 construct that creates a thing and their cert in AWS with CDK. It was created by AWS so it is actually an official package.

@aws-solutions-constructs/aws-iot-lambda

This is a AWS Solutions Construct which integrates a Lambda to a MQTT topic. While it does help make it easier to use an existing lambda, it may be better to just use a IoT Topic Rule with an action to add the message to SQS.

Adding another monitoring Device

Things are defined in the create-things.ts file in the cdk folder. You can add a new thing by adding to the things array. Please note, there is no uniqueness check on the thing suffix. You have to do this manually.

interface ICreateThing {
  suffix: string;
}

export const things: ICreateThing[] = [
  {
    suffix: "Monitor1",
  },
  {
    suffix: "Monitor2",
  },
];