toit-pharo (WIP)

This repo contains a driver for communication between Pharo and a Toit daemon program running on an ESP32 microprocessor.

Communication is through MQTT, used in a synchronous way; the driver sends commands and waits for a response message. The driver supports digital i/o, analog i/o, PWM and I2C. (Servo in the making)

First the program daemon.toit needs to be running on the ESP32. Then you can write in a Playground:

esp := ESP32Driver new brokerIP: 'mqtt://test.mosquitto.org'; deviceName: 'test1'; setup.
esp beDigitalOutputOnPin: 2.  "the on board LED"
esp digitalValue: 1 intoPin: 2. "turn the LED on"

In PharoOfThingsSimplified (https://github.com/robvanlopik/Pots) there is also a driver that uses this one, so you can use the ESP32 as a PotsController.

Message structure

Topics are structured as follows: pots/deviceName/Command where deviceName is used to distinguish between different devices and command is one of: (Version, Mode, DI, DO, AI, AO, PWM, I2COprn, I2CClose, I2CWrite, I2CRead, I2CReadAt, PinList, OutputList, DACList, ADCList, I2CList). The message (payload) is a JSON-encoded array of parameters. Byte arrays (used in I2C operations) are base64 encoded. Responses from the daemon have topic pots/deviceName/+/Result, where the + stands for the command name. The message contains the answer in an array (JSON encoded) that usually has as first element e.g. a pin number or i2c address.

Some limitations/todo's:

• you will have to modify daemon.toit if your ESP32 is not on a 30 pins board, to adapt the address of the MQTT broker, to change the name of the ESP-device. I intend to use toit's asset mechanism for this.
• you need the Toit environment to load daemon.toit. There should be a file that can be directly installed on the ESP32. Doable, but not a priority.
• daemon.toit is not written in an OO fashion, but it is extremely simple. It also doesn't use the container model of Toit.
• although we use asynchronous technology, the system is completely synchronous. When we want to allow out-of-band events (like state changes of gpio pins), we will have to change the design, probably along the lines of the picod system.
• there is NO security, but it would be simple to add username/password authenitcation or TLS data transport.
• there is NO error handling in the daemon, it will simply exit when it gets wrong input (e.g. non existing pin numbers, i/o operations to a pin that is not in that mode, etc). It may be useful to connect the device with USB to your computer and run jag monitor in a separate command shell, so you can read Toit's error messages. Used in conjunction with Pots, errors should not occur.
• you need access to an MQTT broker. You may be able to use test.mosquitto.org, but whem you happen to have a Raspberry Pi (any) around, it is easy to install your own (see e.g. https://randomnerdtutorials.com/how-to-install-mosquitto-broker-on-raspberry-pi/)

Installing daemon.toit

You will need to flash the ESP32 with the toit tools, at least Jaguar. You don't need Visual Studio Code. In short:

• download and install Jaguar (https://github.com/toitlang/jaguar)
• install toit's mqtt package: jag pkg install github.com/toitware/mqtt
• flash the device with the jaguar firmware: jag flash
• edit the file daemon.toit, at least modify the line host := "test.moosquitto.org" to reflect your MQTT broker
• flash daemon.toit to the device: jag run daemon.toit or jag container install daemon daemon.toit

Installling the driver

Metacello new
  baseline: 'ESP32Driver';
    repository: 'github://robvanlopik/toit-pharo:main';
    load.

This will also load the MQTT package by Sven Van Caekenberghe.