Commit e05c49ee authored by Gilles MARCKMANN's avatar Gilles MARCKMANN
Browse files

First implementation of a standalone raspi GUI for Load Cell HX711:

- default values set on raspberry Pi4
- a calibration procedure allows to reset parameters
- a tare button allows to reset value to zero
- figure_raspi_HX711.png gives the way to connect the load cell to the raspberry
This code is base on based on, based on
- update your rapsberry before all:
> sudo aptitude update -y
> sudo aptitude upgrade -y
> sudo reboot
- install Pixel (X11 Desktop), if any:
> sudo dpkg –configure –a
> sudo apt-get install lightdm
> sudo apt –fix-broken install
> sudo apt install lxde lxde-core lxterminal lxappearance
> sudo apt install xinit
> sudo apt install raspberrypi-ui-mods
> sudo apt-get install xutils
> sudo apt-get update
> sudo apt-get dist-upgrade
> sudo reboot
> sudo apt-get install --no-install-recommends xserver-xorg
> sudo apt-get install raspberrypi-ui-mods
> sudo apt-get install lightdm
> sudo startx
- install GPIO:
> sudo pip install RPi.GPIO
> sudo pip install statistics
- install tkinter python module (GUI library for python)
> sudo apt-get install python-tk
- install matplotlib python module:
> sudo pip install matplotlib
> sudo pip2 uninstall backports.functools-lru-cache
> sudo apt install python-backports.functools-lru-cache
#! /usr/bin/python2
import time
import sys
import RPi.GPIO as GPIO
import csv
from tkinter import *
import tkinter.font as tkFont
import numpy
from matplotlib.backends.backend_tkagg import (
FigureCanvasTkAgg, NavigationToolbar2Tk)
# Implement the default Matplotlib key bindings.
from matplotlib.backend_bases import key_press_handler
from matplotlib.figure import Figure
import matplotlib.pyplot as plt
# import class definition
from tatobari.hx711 import HX711
def callback_cleanAndExit():
global _main_window_
global GPIO
def callback_tare():
print("Please wait...")
print("Tare done! Add weight now...")
def callback_CalSet(_parent_window_, text_value, text_unity):
global hx
global referenceUnit
global _WEIGHT_
global _UNITY_
print('Bad balue, no calibration done !')
referenceUnit = float(_WEIGHT_.get())/val
def callback_reset():
global hx
global time
global _UNITY_
print("No weight on scale!")
print("Go to step 2.")
def callback_calibrate():
global hx
global _space_
global _calibration_window_
global _UNITY_
_calibration_window_ = Tk()
_cal_frame_=Frame(_calibration_window_, padx=_space_, pady=_space_ ,relief=GROOVE, background="white")
_indication1_=Label(_cal_frame_, text="1. Remove all weight and click on 'Reset' button", background="white")
_reset_button_=Button(_cal_frame_, text="Reset", command=lambda: callback_reset())
_reset_button_.grid(row=1, column=0 ,columnspan=2, padx=_space_, pady=_space_)
_indication2_=Label(_cal_frame_, text="2. Place a known weight on the scale, indicate the value and click on 'Calibrate' button", background="white")
_val_frame_=Frame(_cal_frame_, padx=_space_,pady=_space_,borderwidth=0, background="white")
_val_label_=Label(_val_frame_,text="Refrence weight:", background="white")
_unity_frame_=Frame(_cal_frame_, padx=_space_,pady=_space_,borderwidth=0, background="white")
_unity_label_=Label(_unity_frame_,text=" Unity symbol:", background="white")
_unity_entry_.delete(0, END)
_cancel_button_=Button(_cal_frame_, text="Cancel", command=_calibration_window_.destroy)
_cancel_button_.grid(row=4, column=0, padx=_space_, pady=_space_)
_cal_button_=Button(_cal_frame_, text="Calibrate", command=lambda: callback_CalSet(_calibration_window_,_val_entry_.get(),_unity_entry_.get()))
_cal_button_.grid(row=4, column=1, padx=_space_, pady=_space_)
def callback_inbetween_mainloop():
global _WEIGHT_
global hx
global _main_window_
#_WEIGHT_.set( val )
_WEIGHT_.set( 1.*int(val*1000)/1000. )
# To get weight from both channels (if you have load cells hooked up
# to both channel A and B), do something like this
#val_A = hx.get_weight_A(1)
#val_B = hx.get_weight_B(1)
#print "A: %s B: %s" % ( val_A, val_B )
except (KeyboardInterrupt, SystemExit):
_main_window_.after(1, callback_inbetween_mainloop)
_main_window_ = Tk()
_FrameTitle_=Frame(_main_window_, borderwidth=0)
_FrameTitle_.grid(row=0, column=0, columnspan=3, padx=_space_, pady=_space_)
_font_style_title_ = tkFont.Font(family="Lucida Grande", size=14)
_label_title_ = Label(_FrameTitle_, text="Scale",bg="white",font=_font_style_title_).pack(side=LEFT,fill=BOTH)
_font_style_title_ = tkFont.Font(family="Lucida Grande", size=14)
_label_title_red_ = Label(_FrameTitle_, text="HX711 load cell",bg="white",font=_font_style_title_,foreground="red").pack(side=LEFT,fill=BOTH)
hx = HX711(5, 6)
# If you're experiencing super random values, change these values to MSB or LSB until to get more stable values.
# According to the HX711 Datasheet, the second parameter is MSB so you shouldn't need to modify it.
hx.set_reading_format("MSB", "MSB")
# To set the reference unit to 1.
# Put 1kg on your sensor or anything you have and know exactly how much it weights.
# set this number divided by the real weight.
referenceUnit = int(1464009/2015)
print("Tare done! Add weight now...")
# Main Label
_font_style_weight_ = tkFont.Font(family="Lucida Grande", size=20)
_weight_frame_=Frame(_main_window_,padx=_space_,pady=_space_, relief=GROOVE)
_weight_label_ = Label(_weight_frame_,padx=_space_,pady=_space_, width=10,textvariable=_WEIGHT_, borderwidth=2,
font=_font_style_weight_,relief=SUNKEN, background="white", anchor=E)
_unity_label_=Label(_main_window_,padx=_space_,pady=_space_, width=5,textvariable=_UNITY_, borderwidth=2,
font=_font_style_weight_, background="white", anchor=W)
# button tare
_buttonTare_=Button(_main_window_, text="Tare", command=callback_tare)
_buttonTare_.grid(row=1, column=3, padx=_space_, pady=_space_)
# button calibrate
_buttonTare_=Button(_main_window_, text="Calibration", command=callback_calibrate)
_buttonTare_.grid(row=1, column=0, padx=_space_, pady=_space_)
# button quit
_buttonQuit_=Button(_main_window_, text="Quit", command=callback_cleanAndExit)
_buttonQuit_.grid(row=3, column=0, padx=_space_, pady=_space_)
# button prendre une mesure
#_buttonMeasure_=Button(_main_window_, text="Record Data", command=callback_add_measure)
#_buttonMeasure_=Button(_main_window_, text="Record Data")
#_buttonMeasure_.grid(row=3, column=1, padx=_space_, pady=_space_)
# button export
#_buttonExport_=Button(_main_window_, text="Export CSV", command=callback_export)
#_buttonExport_=Button(_main_window_, text="Export CSV")
#_buttonExport_.grid(row=3, column=2, padx=_space_, pady=_space_)
_main_window_.after(10, callback_inbetween_mainloop)
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import time
import random
import math
import threading
class HX711:
def __init__(self, dout, pd_sck, gain=128):
self.PD_SCK = pd_sck
self.DOUT = dout
# Last time we've been read.
self.lastReadTime = time.time()
self.sampleRateHz = 80.0
self.resetTimeStamp = time.time()
self.sampleCount = 0
self.simulateTare = False
# Mutex for reading from the HX711, in case multiple threads in client
# software try to access get values from the class at the same time.
self.readLock = threading.Lock()
self.GAIN = 0
self.REFERENCE_UNIT = 1 # The value returned by the hx711 that corresponds to your reference unit AFTER dividing by the SCALE.
self.OFFSET = 1
self.lastVal = long(0)
self.byte_format = 'MSB'
self.bit_format = 'MSB'
# Think about whether this is necessary.
def convertToTwosComplement24bit(self, inputValue):
# HX711 has saturating logic.
if inputValue >= 0x7fffff:
return 0x7fffff
# If it's a positive value, just return it, masked with our max value.
if inputValue >= 0:
return inputValue & 0x7fffff
if inputValue < 0:
# HX711 has saturating logic.
if inputValue < -0x800000:
inputValue = -0x800000
diff = inputValue + 0x800000
return 0x800000 + diff
def convertFromTwosComplement24bit(self, inputValue):
return -(inputValue & 0x800000) + (inputValue & 0x7fffff)
def is_ready(self):
# Calculate how long we should be waiting between samples, given the
# sample rate.
sampleDelaySeconds = 1.0 / self.sampleRateHz
return time.time() >= self.lastReadTime + sampleDelaySeconds
def set_gain(self, gain):
if gain is 128:
self.GAIN = 1
elif gain is 64:
self.GAIN = 3
elif gain is 32:
self.GAIN = 2
# Read out a set of raw bytes and throw it away.
def get_gain(self):
if self.GAIN == 1:
return 128
if self.GAIN == 3:
return 64
if self.GAIN == 2:
return 32
# Shouldn't get here.
return 0
def readRawBytes(self):
# Wait for and get the Read Lock, incase another thread is already
# driving the virtual HX711 serial interface.
# Wait until HX711 is ready for us to read a sample.
while not self.is_ready():
self.lastReadTime = time.time()
# Generate a 24bit 2s complement sample for the virtual HX711.
rawSample = self.convertToTwosComplement24bit(self.generateFakeSample())
# Read three bytes of data from the HX711.
firstByte = (rawSample >> 16) & 0xFF
secondByte = (rawSample >> 8) & 0xFF
thirdByte = rawSample & 0xFF
# Release the Read Lock, now that we've finished driving the virtual HX711
# serial interface.
# Depending on how we're configured, return an orderd list of raw byte
# values.
if self.byte_format == 'LSB':
return [thirdByte, secondByte, firstByte]