hx711-multi

HX711 class to sample 24-bit ADCs with Python 3 on a Raspberry Pi Rasperry Pi Zero, 2 or 3

Description

This library allows to configure and read from one or multiple HX711 load cells with a Raspberry Pi. It was developed and tested in Python 3.8 on Raspberry Pi 4B with Raspberry Pi OS Lite v5.10.

Capabilities:

• Configure Raspberry Pi digital pins for reading measurements
• Configure Raspberry Pi SCK pin, or clock pin, used for configuring channel and triggering measurements
• Configure Channel (A | B)
• Configure Channel A Gain (128 | 64)
• Power down load cell
• Power up load cell
• Zero load cell at start
• Configure individual weight multiples for calibration of each scale to real-world weight
• Read raw measurements from load cells
• Read weight measurements from load cells

This package requires RPi.GPIO to be installed in Python 3.

Hardware

Documentation is included in Docs folder. Default rate of HX711 is 10Hz, unless you wire the digital power (DVDD) to the RATE pin (15), at which point you can sample at 80Hz. I've included a picture of this wiring if desired.

Getting started

Install with pip3 install hx711_multi

Basic usage example:

#!/usr/bin/env python3

from hx711_multi import HX711
from time import perf_counter
import RPi.GPIO as GPIO  # import GPIO

#init GPIO (should be done outside HX711 module in case you are using other GPIO functionality)
GPIO.setmode(GPIO.BCM)  # set GPIO pin mode to BCM numbering

dout_pins = [13,21,16,26,19]
sck_pin = 20
weight_multiples = [4489.80, 4458.90, 4392.80, 1, -5177.15]

hx711 = HX711(dout_pins=dout_pins, sck_pin=sck_pin, all_or_nothing=False, log_level='CRITICAL')  # create an object
hx711.reset()
hx711.zero()
hx711.set_weight_multiples(weight_multiples=weight_multiples)

# read until keyboard interrupt
try:
    while True:
        start = perf_counter()
        raw_vals = hx711.read_raw(readings_to_average=10)
        weights = hx711.read_weight(use_prev_read=True)
        read_duration = perf_counter() - start
        print('\nread duration: {:.3f} seconds'.format(read_duration))
        print('raw', ['{:.3f}'.format(x) if x is not None else None for x in raw_vals])
        print(' wt', ['{:.3f}'.format(x) if x is not None else None for x in weights])
except KeyboardInterrupt:
    print('Keyboard interrupt..')
except Exception as e:
    print(e)

# cleanup GPIO
GPIO.cleanup()

Author

• James Morris

License

• Free software: MIT license

Credits

• https://github.com/gandalf15/HX711/ as base starting point