Geiger counter

geigercounter.py

import time
import datetime
import RPi.GPIO as GPIO
from collections import deque

counts = deque()
usvh_ratio = 0.00812037037037  # This is for the J305 tube

geigerChannel = 7

# https://sourceforge.net/p/raspberry-gpio-python/wiki/BasicUsage/
GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(True)


# This method fires on edge detection (the pulse from the counter board)
def countme(channel):
    global counts
    timestamp = datetime.datetime.now()
    counts.append(timestamp)


# Set the input with falling edge detection for geiger counter pulses
GPIO.setup(geigerChannel, GPIO.IN)

# https://sourceforge.net/p/raspberry-gpio-python/wiki/Inputs/
GPIO.add_event_detect(geigerChannel, GPIO.FALLING, callback=countme)

loop_count = 0

# In order to calculate CPM we need to store a rolling count of events in the last 60 seconds
# This loop runs every second to update measurements and removes elements from the queue
# that are older than 60 seconds
while True:
    loop_count = loop_count + 1

    try:
        while counts[0] < datetime.datetime.now() - datetime.timedelta(seconds=60):
            counts.popleft()
    except IndexError:
        pass  # there are no records in the queue.

    if loop_count == 10:
        # Every 10th iteration (10 seconds), store a measurement in Influx
        measurements = [
            {
                'measurement': 'sensor',
                'fields': {
                    'cpm': int(len(counts)),
                    'usvh': "{:.2f}".format(len(counts) * usvh_ratio)
                }
            }
        ]
        print(measurements)
        loop_count = 0

    time.sleep(1)

install.sh

pip3 install spidev RPi.GPIO
python3 geigercounter.py