Commit d9318509 authored by Forquet Nicolas's avatar Forquet Nicolas
Browse files

* start to implement the measurement function

parent 6392ba7f
......@@ -4,7 +4,7 @@ OHMPY_code is a program to control the low-cost and open source resistivity mete
OHMPY, it has been developed by Rémi CLEMENT,Vivien DUBOIS, Nicolas FORQUET (IRSTEA) and Yannick FARGIER (IFSTTAR).
print('OHMPI start' )
print()'Import library')
print('Import library')
import RPi.GPIO as GPIO
......@@ -17,6 +17,7 @@ import os
import sys
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn
import pandas as pd
display start time
......@@ -28,10 +29,13 @@ print(current_time.strftime("%Y-%m-%d %H:%M:%S"))
nb_electrodes = 32 # maximum number of electrodes on the resistivity meter
injection_time = 5 # Current injection time in second
injection_duration = 5 # Current injection duration in second
nbr_meas= 900 # Number of times the quadripole sequence is repeated
sequence_delay= 30 # Delay in seconds between 2 sequences
stack= 1 # repetition of the current injection for each quadripole
R_ref = 50 # reference resistance value in ohm
coef_p0 = 2.02 # slope for current conversion for ADS.P0, measurement in ???
coef_p1 = 2.02 # slope for current conversion for ADS.P1, measurement in ???
......@@ -72,8 +76,58 @@ def read_quad(filename, nb_elec):
print("Error: An electrode index is used twice at line " + str(test_same_elec[i]+1))
return output
return output
# perform a measurement
def run_measurement(nb_stack, injection_deltat, Rref, coefp0, coefp1):
i2c = busio.I2C(board.SCL, board.SDA) # I2C protocol setup
ads = ADS.ADS1115(i2c, gain=2/3) # I2C communication setup
# inner variable initialization
# GPIO initialization
GPIO.setup(7, GPIO.OUT)
GPIO.setup(8, GPIO.OUT)
# resistance measurement
for n in range(0,3+2*nbr_stack-1) :
print("stack "+ str(n+1))
if (n % 2) == 0:
GPIO.output(7, GPIO.HIGH) # polarité n°1
GPIO.output(7, GPIO.LOW) # polarité n°1 également ?
GPIO.output(8, GPIO.HIGH) # current injection
time.sleep(injection_deltat) # delay depending on current injection duration
Ia1 = AnalogIn(ads,ADS.P0).voltage * coeffp0 # reading current value on ADS channel A0
Ib1 = AnalogIn(ads,ADS.P1).voltage * coeffp1 # reading current value on ADS channel A1
Vm1 = AnalogIn(ads,ADS.P2).voltage # reading voltage value on ADS channel A2
Vn1 = AnalogIn(ads,ADS.P3).voltage # reading voltage value on ADS channel A3
GPIO.output(8, GPIO.LOW)# stop current injection
I1= (Ia1 - Ib1)/Rref;
Vmn1= (Vm1 - Vn1);
if (n % 2) == 0:
# return averaged values
output = pd.DataFrame({
return output
Initialization of GPIO channels
......@@ -86,32 +140,29 @@ for i in pinList:
GPIO.output(i, GPIO.HIGH)
Reading the quadripole file
Main loop
N=read_quad("ABMN.txt",nb_electrodes) # load quadripole file
for g in range(0,nbr_meas): # for time-lapse monitoring
Selection electrode activées pour chaque quadripole
for i in range(0,N.shape[0]): # boucle sur les quadripôles, qui tient compte du nombre de quadripole dans le fichier ABMN
# call switch_mux function
for i in range(0,N.shape[0]): # loop over quadripoles
# call the switch_mux function to switch to the right electrodes
# run a measurement
run_measurement(stack, injection_duration, R_ref, coef_p0, coef_p1)
# save data and print in a text file
# reset multiplexer channels
GPIO.output(12, GPIO.HIGH); GPIO.output(16, GPIO.HIGH); GPIO.output(20, GPIO.HIGH); GPIO.output(21, GPIO.HIGH); GPIO.output(26, GPIO.HIGH)
GPIO.output(18, GPIO.HIGH); GPIO.output(23, GPIO.HIGH); GPIO.output(24, GPIO.HIGH); GPIO.output(25, GPIO.HIGH); GPIO.output(19, GPIO.HIGH)
GPIO.output(6, GPIO.HIGH); GPIO.output(13, GPIO.HIGH); GPIO.output(4, GPIO.HIGH); GPIO.output(17, GPIO.HIGH); GPIO.output(27, GPIO.HIGH)
GPIO.output(22, GPIO.HIGH); GPIO.output(10, GPIO.HIGH); GPIO.output(9, GPIO.HIGH); GPIO.output(11, GPIO.HIGH); GPIO.output(5, GPIO.HIGH)
time.sleep(sequence_delay);#waiting next measurement
time.sleep(sequence_delay); #waiting next measurement (time-lapse)
Save result in txt file
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