Implementation of the mcp3004/mcp3008 ADC chip.
Features:
- Provides access to pseudo differential mode
- Does not assume Vref and Vin are the same
And while this implementation is more verbose, it does so in order to aid in clarity of understanding and for learning.
import { mcp300x } = from '@johntalton/mcp300X'
const spi = ...
const adc = mcp300X.from({ bus: spi, Vref: 5, channels: 8 })
const result = await dev.readADC(channel)
console.log('normalized value', result.normal)
console.log('voltage', result.V)In the usage above our Analog circuitry is running at 5V, while the chip is running at 3.3V configuration.
The returned result object holds the normal-ized value, as well as the raw ADC value and the ```V``oltage as calculated.
The mode allows the bonding of two channels in +/- or -/+ configurations.
The readADCDiff method can be passed a single "index-channel" or the order +/- pair.
From the spec:
| Idx | +ch / -ch |
|---|---|
| 1st | Ch0 / Ch1 |
| 2nd | Ch1 / Ch0 |
| 3rd | Ch2 / Ch3 |
| etc ... |
...
dev.readADCDiff(6).then(result => { ... }) // index-channel 6 or +Ch5 / -Ch4