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Ohmpi.py is a program to control a low-cost and open hardward resistivity meter OhmPi that has been developed by Rémi CLEMENT(INRAE),Vivien DUBOIS(INRAE),Hélène GUYARD(IGE), Nicolas FORQUET (INRAE), and Yannick FARGIER (IFSTTAR).
"""
print('\033[1m'+'\033[31m'+' ________________________________')
print('| _ | | | || \/ || ___ \_ _|')
print('| | | | |_| || . . || |_/ / | |' )
print('| | | | _ || |\/| || __/ | |')
print('\ \_/ / | | || | | || | _| |_')
print(' \___/\_| |_/\_| |_/\_| \___/ ')
print('\033[0m')
print('OhmPi start' )
print('Vers: 1.51')
import time , board, busio, numpy, os, sys, json, glob,os.path,adafruit_tca9548a
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn
from pandas import DataFrame
from datetime import datetime
from adafruit_mcp230xx.mcp23008 import MCP23008
from adafruit_mcp230xx.mcp23017 import MCP23017
import digitalio
from digitalio import Direction
from gpiozero import CPUTemperature
current_time = datetime.now()
print(current_time.strftime("%Y-%m-%d %H:%M:%S"))
"""
R_shunt = 0.2# reference resistance value in ohm
coef_p2 = 2.50# slope for current conversion for ADS.P2, measurement in V/V
coef_p3 = 2.50 # slope for current conversion for ADS.P3, measurement in V/V
offset_p2= 0
offset_p3= 0
integer=10
meas=numpy.zeros((3,integer))
with open('ohmpi_param.json') as json_file:
pardict = json.load(json_file)
i2c = busio.I2C(board.SCL, board.SDA) #activation du protocle I2C
mcp = MCP23008(i2c, address=0x20) #connexion I2C MCP23008, injection de courant
ads_current = ADS.ADS1115(i2c, gain=16,data_rate=860, address=0X48)# connexion ADS1115, pour la mesure de courant
ads_voltage = ADS.ADS1115(i2c, gain=2/3,data_rate=860, address=0X49)# connexion ADS1115, pour la mesure de courant
#initialisation desvoie pour la polarité
pin0 = mcp.get_pin(0)
pin0.direction = Direction.OUTPUT
pin1 = mcp.get_pin(1)
pin1.direction = Direction.OUTPUT
pin0.value = False
pin1.value = False
# Initialisation MUX
Elec_A= adafruit_tca9548a.TCA9548A(i2c, 0X76)
Elec_B= adafruit_tca9548a.TCA9548A(i2c, 0X71)
Elec_M= adafruit_tca9548a.TCA9548A(i2c, 0X74)
Elec_N= adafruit_tca9548a.TCA9548A(i2c, 0X70)
"""
functions
"""
# function swtich_mux select the right channels for the multiplexer cascade for electrodes A, B, M and N.
def switch_mux_on(quadripole):
elec_adress=[0x76,0X71,0x74,0x70]
for i in range(0,4):
tca= adafruit_tca9548a.TCA9548A(i2c, elec_adress[i]) #choose MUX A B M or N
if quadripole[i] < 17:
nb_i2C=7
a=quadripole[i]
elif quadripole[i] > 16 and quadripole[i] < 33:
nb_i2C=6
a=quadripole[i]-16
elif quadripole[i] > 32 and quadripole[i] < 49:
nb_i2C=5
a=quadripole[i]-32
elif quadripole[i] > 48 and quadripole[i] < 65:
nb_i2C=4
a=quadripole[i]-48
mcp2 = MCP23017(tca[nb_i2C])
mcp2.get_pin(a-1).direction=digitalio.Direction.OUTPUT
mcp2.get_pin(a-1).value=True
def switch_mux_off(quadripole):
elec_adress=[0x76,0X71,0x74,0x70]
for i in range(0,4):
tca= adafruit_tca9548a.TCA9548A(i2c, elec_adress[i]) #choose MUX A B M or N
if quadripole[i] < 17:
nb_i2C=7
a=quadripole[i]
elif quadripole[i] > 16 and quadripole[i] < 33:
nb_i2C=6
a=quadripole[i]-16
elif quadripole[i] > 32 and quadripole[i] < 49:
nb_i2C=5
a=quadripole[i]-32
elif quadripole[i] > 48 and quadripole[i] < 65:
nb_i2C=4
a=quadripole[i]-48
mcp2 = MCP23017(tca[nb_i2C])
mcp2.get_pin(a-1).direction=digitalio.Direction.OUTPUT
mcp2.get_pin(a-1).value=False
#function to switch off mux
def ZERO_mux(nb_elec):
elec_adress=[0x76,0X71,0x74,0x70]
tca= adafruit_tca9548a.TCA9548A(i2c, elec_adress[i]) #choose MUX A B M or N
for y in range(0,nb_elec):
qd=y+1
if qd < 17:
nb_i2C=7
a=qd
elif qd > 16 and qd < 33:
nb_i2C=6
a=qd-16
elif qd > 32 and qd < 49:
nb_i2C=5
a=qd-32
elif qd > 48 and qd < 65:
nb_i2C=4
a=qd-48
mcp2 = MCP23017(tca[nb_i2C])
mcp2.get_pin(a-1).direction=digitalio.Direction.OUTPUT
mcp2.get_pin(a-1).value= False
# function to find rows with identical values in different columns
def find_identical_in_line(array_object):
output = []
if array_object.ndim == 1:
temp = numpy.zeros(4)
for i in range(len(array_object)):
temp[i] = numpy.count_nonzero(array_object == array_object[i])
if any(temp > 1):
output.append(0)
else:
for i in range(len(array_object[:,1])):
temp = numpy.zeros(len(array_object[1,:]))
for j in range(len(array_object[1,:])):
temp[j] = numpy.count_nonzero(array_object[i,:] == array_object[i,j])
if any(temp > 1):
output.append(i)
return output
# read quadripole file and apply tests
def read_quad(filename, nb_elec):
output = numpy.loadtxt(filename, delimiter=" ",dtype=int) # load quadripole file
# locate lines where the electrode index exceeds the maximum number of electrodes
test_index_elec = numpy.array(numpy.where(output > nb_elec))
# locate lines where an electrode is referred twice
test_same_elec = find_identical_in_line(output)
# if statement with exit cases (rajouter un else if pour le deuxième cas du ticket #2)
if test_index_elec.size != 0:
for i in range(len(test_index_elec[0,:])):
print("Error: An electrode index at line "+ str(test_index_elec[0,i]+1)+" exceeds the maximum number of electrodes")
sys.exit(1)
elif len(test_same_elec) != 0:
for i in range(len(test_same_elec)):
print("Error: An electrode index is used twice at line " + str(test_same_elec[i]+1))
sys.exit(1)
else:
return output
def run_measurement(nb_stack, injection_deltat, R_shunt, coefp2, coefp3, elec_array):
start_time=time.time()
# inner variable initialization
sum_I=0
sum_Vmn=0
sum_Ps=0
# injection courant and measure
mcp = MCP23008(i2c, address=0x20)
pin0 = mcp.get_pin(0)
pin0.direction = Direction.OUTPUT
pin1 = mcp.get_pin(1)
pin1.direction = Direction.OUTPUT
pin0.value = False
pin1.value = False
for n in range(0,3+2*nb_stack-1) :
# current injection
if (n % 2) == 0:
pin1.value = True
pin0.value = False # current injection polarity n°1
pin0.value = True
pin1.value = False# injection de courant polarity n°2
start_delay=time.time()
time.sleep(injection_deltat) # delay depending on current injection duration
meas[0,k] = ((AnalogIn(ads_current,ADS.P0).voltage/50)/R_shunt)*1000 # reading current value on ADS channel A0
meas[1,k] = AnalogIn(ads_voltage,ADS.P0).voltage * coefp2*1000
meas[2,k] = AnalogIn(ads_voltage,ADS.P1).voltage * coefp3*1000 # reading voltage value on ADS channel A2
pin1.value = False; pin0.value = False# stop current injection
sum_I=sum_I+(numpy.mean(meas[0,:]))
Vmn1=((numpy.mean(meas[1,:]))-(numpy.mean(meas[2,:])))
sum_Vmn=sum_Vmn-Vmn1
sum_Ps=sum_Ps+Vmn1
sum_Vmn=sum_Vmn+Vmn1
sum_Ps=sum_Ps+Vmn1
time.sleep((end_delay-start_delay)-(end_calc-end_delay))
# return averaged values
output = DataFrame({
"time":[datetime.now()],
"A":elec_array[0],
"B":elec_array[1],
"M":elec_array[2],
"N":elec_array[3],
"Vmn [mV]":[(sum_Vmn/(3+2*nb_stack-1))],
"I [mA]":[(sum_I/(3+2*nb_stack-1))],
# "Rab [KOhm]":[(Tab*2.47)/(sum_I/(3+2*nb_stack-1))/1000],
# "Tx [V]":[Tx*2.47],
"Ps [mV]":[(sum_Ps/(3+2*nb_stack-1))],
"CPU temp [°C]":[cpu.temperature],
# "Hardware temp [°C]":[read_temp()-8],
"Time [S]":[(-start_time+time.time())]
# "Rcontact[ohm]":[Rc],
# "Rsoil[ohm]":[Rsoil],
# "Rab_theory [Ohm]":[(Rc*2+Rsoil)]
# Dead time equivalent to the duration of the current injection pulse
})
print(output.to_string())
time.sleep(1)
return output
# save data
def append_and_save(path, last_measurement):
if os.path.isfile(path):
# Load data file and append data to it
with open(path, 'a') as f:
last_measurement.to_csv(f, header=False)
else:
# create data file and add headers
with open(path, 'a') as f:
last_measurement.to_csv(f, header=True)
"""
Main loop
"""
N=read_quad("dd.txt",pardict.get("nb_electrodes")) # load quadripole file
ZERO_mux(pardict.get("nb_electrodes"))
for g in range(0,pardict.get("nbr_meas")): # for time-lapse monitoring
for i in range(0,N.shape[0]): # loop over quadripoles
# call the switch_mux function to switch to the right electrodes
current_measurement = run_measurement(pardict.get("stack"), pardict.get("injection_duration"), R_shunt, coef_p2, coef_p3, N[i,])
#save data and print in a text file
print(i+1,'/',N.shape[0])
print('end of sequence')
ZERO_mux(pardict.get("nb_electrodes"))
time.sleep(pardict.get("sequence_delay")) #waiting next measurement (time-lapse)