nodemcu-firmware/docs/modules/hx711.md

# HX711 Module
| Since  | Origin / Contributor  | Maintainer  | Source  |
| :----- | :-------------------- | :---------- | :------ |
| 2015-10-09 | [Chris Takahashi](https://github.com/christakahashi) | [Chris Takahashi](https://github.com/christakahashi) | [hx711.c](../../app/modules/hx711.c)|

This module provides access to an [HX711 load cell amplifier/ADC](https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide). The HX711 is an inexpensive 24bit ADC with programmable 128x, 64x, and 32x gain. Currently only channel A at 128x gain is supported.

Note: To save ROM image space, this module is not compiled into the firmware by default.

## hx711.init()

Initialize io pins for hx711 clock and data.

#### Syntax
`hx711.init(clk, data)`

#### Parameters
- `clk` pin the hx711 clock signal is connected to
- `data` pin the hx711 data signal is connected to

#### Returns
`nil`

#### Example
```lua
-- Initialize the hx711 with clk on pin 5 and data on pin 6
hx711.init(5,6)
```

## hx711.read()

Read digital loadcell ADC value.

#### Syntax
`hx711.read(mode)`

#### Parameters
`mode` ADC mode.  This parameter is currently ignored and reserved to ensure backward compatibility if support for additional modes is added. Currently only channel A @ 128 gain is supported.

|mode | channel | gain |
|-----|---------|------|
| 0   | A       | 128  |

#### Returns
a number (24 bit signed ADC value extended to the machine int size)

#### Example
```lua
-- Read ch A with 128 gain.
raw_data = hx711.read(0)
```