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@Richard-Major
Forked from underdoeg/hx711.py
Last active February 20, 2023 01:05
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Python port for RaspberryPI of the HX711 Breakout Board
#!/usr/bin/python3
# Development for reading sparkfun HX711 load cell amp
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
class HX711:
def __init__(self, dout, pd_sck, gain=128, readBits=24):
self.PD_SCK = pd_sck
self.DOUT = dout
self.readBits = readBits
self.twosComplementOffset = 1 << readBits
self.twosComplementCheck = self.twosComplementOffset >> 1
GPIO.setup(self.PD_SCK, GPIO.OUT)
GPIO.setup(self.DOUT, GPIO.IN)
self.GAIN = 0
self.OFFSET = 0
self.SCALE = 1
self.lastVal = 0
self.set_gain(gain)
def is_ready(self):
return GPIO.input(self.DOUT) == 0
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
GPIO.output(self.PD_SCK, False)
self.read()
def waitForReady(self):
while not self.is_ready():
pass
def setChannelGainFactor(self):
for i in range(self.GAIN):
GPIO.output(self.PD_SCK, True)
GPIO.output(self.PD_SCK, False)
def correctForTwosComplement( self , unsignedValue ):
if ( unsignedValue >= self.twosComplementCheck ):
return -self.twosComplementOffset + unsignedValue
else:
return unsignedValue
def read(self):
self.waitForReady();
unsignedValue = 0
for i in range(0,self.readBits):
GPIO.output(self.PD_SCK, True)
unsignedValue = unsignedValue << 1
GPIO.output(self.PD_SCK, False)
bit = GPIO.input(self.DOUT)
if ( bit ):
unsignedValue = unsignedValue | 1
self.setChannelGainFactor()
signedValue = self.correctForTwosComplement( unsignedValue )
self.lastVal = signedValue
return self.lastVal
def read_average(self, times=3):
sum = 0
for i in range(times):
sum += self.read()
return sum / times
def get_value(self, times=3):
return self.read_average(times) - self.OFFSET
def get_units(self, times=3):
return self.get_value(times) / self.SCALE
def tare(self, times=15):
sum = self.read_average(times)
self.set_offset(sum)
def set_scale(self, scale):
self.SCALE = scale
def set_offset(self, offset):
self.OFFSET = offset
def power_down(self):
GPIO.output(self.PD_SCK, False)
GPIO.output(self.PD_SCK, True)
def power_up(self):
GPIO.output(self.PD_SCK, False)
############# EXAMPLE
hx = HX711(27, 17,128)
hx.set_scale(7050)
hx.tare()
while True:
try:
val = hx.get_units(1)
offset = max(1,min(80,int(val+40)))
otherOffset = 100-offset;
print (" "*offset+"#"+" "*otherOffset+"{0: 4.4f}".format(val));
except (KeyboardInterrupt, SystemExit):
break
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