obniz
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obniz sdk for javascript
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# MQ2
High sensitve multiple gas sensor especially for LPG, Propane and Hydrogen.
If you are using just MQ2(not module), Then prepare load resistance around 2k ohm.
This sensor need pre-heating. To get stable output, wait for heat-up, minimum 2 minutes.
This library get analog voltage from a sensor. Output voltage will increase regarding gas level. When you need actual level (ppm), you should do calibrate the sensor and prepare a formula.
## wired(obniz, { vcc, gnd, do, ao});
name | type | required | default | description
--- | --- | --- | --- | ---
vcc | `number(obniz io)` | no | | VCC or H on MQ2.
gnd | `number(obniz io)` | no | | GND or H on MQ2.
do | `number(obniz io)` | no | | digital out
ao | `number(obniz io)` | no | | analog out
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.onchangeanalog = function(voltage) {
console.log(voltage);
}
```
## startHeating()
It start heating.
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
mq2.startHeating();
```
## [await] heatWait(sec: number)
It start heating and wait for a while.
You can update wait time.
name | type | required | default | description
--- | --- | --- | --- | ---
sec | `number` | no | 120 | seconds for wait
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.onchangeanalog = function(voltage) {
console.log(voltage);
}
```
## onchangeanalog = function(voltage: number)
Specified function will be called every voltage change.
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.onchangeanalog = function(voltage) {
console.log(voltage);
}
```
## onexceedvoltage = function(voltage: number)
Specified function will be called only when a voltage exceed voltageLimit variable.
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.voltageLimit = 1.0
mq2.onexceedvoltage = function(voltage) {
console.log(voltage);
}
```
## voltageLimit = number
It define the level of onexceedvoltage call.
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.voltageLimit = 1.0
mq2.onexceedvoltage = function(voltage) {
console.log(voltage);
}
```
## onchangedigital = function(voltage: number)
This function only be called when do was specified at wired function.
do output high/low regarding output. It compared in a module.
This function will be called every change of do.
```Javascript
// Javascript Example
var mq2 = obniz.wired("MQ2", {vcc:3, gnd:2, do:1, ao:0});
await mq2.heatWait();
mq2.onchangedigital = function(value) {
console.log(value);
}
```