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Adding SEN0322 O2 Sensor Driver Support #1075

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23 changes: 23 additions & 0 deletions examples/drivers/sensors/sen0322/main.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
import Sensor from "embedded:sensor/OxygenGasSensor-OSensor/SEN0322";
import Timer from "timer";

const knownOxygenVal = 20.9; // Known concentration of oxygen in the air, for calibration
const oxygenMV = 0; // The value marked on the sensor, set to 0 unless otherwise required

const sensor = new Sensor({
sensor: {
...device.I2C.default,
io: device.io.I2C
}
});

sensor.configure({
vol: knownOxygenVal,
mv: oxygenMV
});

Timer.repeat(() =>
{
const sample = sensor.sample();
trace(`O2: ${sample.O} ppm\n`);
}, 500);
9 changes: 9 additions & 0 deletions examples/drivers/sensors/sen0322/manifest.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
{
"include": [
"$(MODDABLE)/modules/io/manifest.json",
"$(MODDABLE)/modules/drivers/sensors/sen0322/manifest.json"
],
"modules": {
"*": "./main"
}
}
9 changes: 9 additions & 0 deletions modules/drivers/sensors/sen0322/manifest.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
{
"modules": {
"embedded:sensor/OxygenGasSensor-OSensor/SEN0322": "$(MODDABLE)/modules/drivers/sensors/sen0322/sen0322"
},
"preload": [
"embedded:sensor/OxygenGasSensor-OSensor/SEN0322"
]
}

96 changes: 96 additions & 0 deletions modules/drivers/sensors/sen0322/sen0322.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,96 @@
/*
* Copyright 2023 Moddable Tech, Inc.
* Revised: March 27, 2023
*
* This file is part of the Moddable SDK.
*
* This work is licensed under the
* Creative Commons Attribution 4.0 International License.
* To view a copy of this license, visit
* <https://creativecommons.org/licenses/by/4.0>.
* or send a letter to Creative Commons, PO Box 1866,
* Mountain View, CA 94042, USA.
*
*/

/*
SEN0322 - Oxygen Sensors
https://www.dfrobot.com/product-2052.html
Datasheet: https://wiki.dfrobot.com/Gravity_I2C_Oxygen_Sensor_SKU_SEN0322
Reference Driver: https://github.com/DFRobot/DFRobot_OxygenSensor/blob/master/DFRobot_OxygenSensor.cpp
*/


import Timer from "timer";
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Our ECMA-419 sensor drivers usually include a header with:

  • Copyright notice
  • Full name of part
  • Link to relevant manufacturer data sheets
  • Link to any implementations used as a reference


const Register = Object.freeze({
OXYGEN_DATA: 0x03, ///< register for oxygen data
USER_SET: 0x08, ///< register for users to configure key value manually
AUTUAL_SET: 0x09, ///< register that automatically configure key value
GET_KEY: 0x0A ///< register for obtaining key value
});

const I2C_ADDR = 0x73;

class SEN0322
{
#io;
#key;

constructor(options) {
this.#io = new options.sensor.io({
address: I2C_ADDR,
hz: 100_000,
...options.sensor
});
}

configure(options)
{
if (undefined !== options.vol)
{
const vol = options.vol;
const mv = options.mv ?? 0;
if (0 > vol || vol > 25)
throw new RangeError("invalid O2 concentration (must be 0-25)");

const io = this.#io;
let keyValue = vol * 10;

if (-0.000001 < mv && mv < 0.000001)
io.write(Uint8Array.of(Register.USER_SET, keyValue));
else
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The throw above will always, so the content of this else clause can be directly inline below.

{
keyValue = vol / mv * 1000;
io.write(Uint8Array.of(Register.AUTUAL_SET, keyValue));
}
}
}
#setKey()
{
const io = this.#io;
io.write(Uint8Array.of(Register.GET_KEY));
const curKey = (new Uint8Array(io.read(1)))[0];
if (curKey)
this.#key = curKey / 1000.0;
else
this.#key = 20.9 / 120.0;
}
close()
{
this.#io?.close();
this.#io = undefined;
}
sample()
{
const io = this.#io;
this.#setKey();
io.write(Uint8Array.of(Register.OXYGEN_DATA));
Timer.delay(100);
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Hmm, this pauses the VM. I would not use this driver for this alone. Would be nice to find a different way to code this. At the very least document it at the top or readme.

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Agreed. A simple solution would be to have a timer in the driver to poll the value every 100ms. The driver would store the most recent value and return it from sample().

Because sample()1 is allowed to return undefined`, the driver could clear the cached sample after it is read once. The benefit is that a caller will know when they have a truly new reading.

const rxbuf = new Uint8Array(io.read(3));
const oxygenPercent = this.#key * (rxbuf[0] + (rxbuf[1] / 10.0) + (rxbuf[2] / 100.0));
return { O: oxygenPercent * 10_000 }; // O2 concentration in PPM
}

}
export default SEN0322;