I2CBus Software over GPIO

Library to wrap I2CBus over top of GPIO abstraction.

Motivation

Because 🤷🏻‍♂️, but also:

To further understanding and testing of I²C bus interactions and expose unique capabilities.

And to provide a I2CBus abstraction that is capable of being the source bus for a wider range of sensors implemented overtop of this API.

Primary testing of the has been done over the following configuration:

SerialPort -> Excamera I2CDriver -> i2c-bus-excamera -> pcf8574 -> i2c-bus-soft -> device*

* where devices include EEPROM / AHT20 / DS1841 and others

The pcf8574 acts as the primary GPIO interface as it naturally floats HIGH and does not have the concept of input/output direction. This lends itself to I²C control. However it is itself a I2CBus device, that is running overtop of the Excamera Serial i2cDriver.

Example

import { I2CBusGPIO } from '@johntalton/i2c-bus-soft'

/*
	using some custom GPIO device implement the set/get interface
	(note true maps to Floating/HIGH while false is LOW)
*/
const gpioBus = new I2CBusGPIO({
	/**
	 * @param {boolean} scl
	 * @param {boolean} sda
	 */
	async set(scl, sda) {
		// set scl and sda according to parameters
	},

	async get() {
		// return scl and sda as boolean values
		return { scl, sda }
	}
})

// now the bus can be used as normal I2CBus
// such as to scan
const devices = await gpioBus.scan()
for (const device of devices) {
	console.log('found device at', '0x' + device.toString(16).toUpperCase().padStart(2, '0'))
}

// or using a attached device
const adt = new ADT7410(new I2CAddressedBus(gpioBus, 0x48))
const id = await adt.getId()
const temp = await adt.getTemperature()

Using the PCF8574

Using pin 6/7 used for SDA/SCL respectively

import { I2CBusGPIO } from '@johntalton/i2c-bus-soft'
import { PCF8574 } from '@johntalton/pcf8574'

const device = new PCF8574(/* some other bus */)

const gpioBus = new I2CBusGPIO({
	async set(scl, sda) {
		await device.writePort({ p6: sda, p7: scl })
	},

	async get() {
		const { p6, p7 } = await device.readPort()
		return { scl, sda }
	}
})