parkit.py

import RPi.GPIO as GPIO
import time

#GPIO Mode (BOARD / BCM)
GPIO.setmode(GPIO.BCM)

# Define the update rate of this program
# Avoid large values as this will needlessly cycle and heat
# the BCM chip on the board. In theory this value could be as
# low as 0.5 - 1 Hz given our usecase, but 50 is used for responsivity
CLOCK_RATE_HZ = 50

# Input Pins: We recieve signals here
READ_STATE_C = 5
READ_STATE_D = 6
READ_STATE_E = 13
READ_STATE_F = 19

# Ouptut Pins: We send signals here
OUT_INPUT_A = 23
OUT_INPUT_B = 24
OUT_CLOCK = 14

#set GPIO direction (IN / OUT)
GPIO.setup(
   [READ_STATE_C, READ_STATE_D, READ_STATE_E, READ_STATE_F],
   GPIO.IN, pull_up_down=GPIO.PUD_DOWN
)
GPIO.setup(OUT_INPUT_A, GPIO.OUT)
GPIO.setup(OUT_INPUT_B, GPIO.OUT)
GPIO.setup(OUT_CLOCK, GPIO.OUT)

STATE_LIST = {
	'0000' : 'HW_INIT',
	'0001' : 'BOOT_SUCCESS',
	'0010' : 'NET_CHECK',
	'0100' : 'MS_OFFLINE',
	'0101' : 'OFFLINE_EMPTY',
	'0110' : 'OFFLINE_TAKEN',
	'1000' : 'MS_ONLINE',
	'1001' : 'ONLINE_FREE',
	'1010' : 'ONLINE_TAKEN',
	'1011' : 'ONLINE_RESERVED',
	'1111' : 'HW_DISABLED'
}

FAULT_STATE_UNKOWN = 'FAULT_STATE_UNKNOWN'

SIG_NO_OP = (0, 0)
SIG_ALPHA = (0, 1)
SIG_BETA =  (1, 0)
SIG_GAMMA = (1, 1)

def send_clock():
    GPIO.output(OUT_CLOCK, True)
    time.sleep(0.1)
    GPIO.output(OUT_CLOCK, False)

def send_signal(signal):
    GPIO.output(OUT_INPUT_A, signal[0])
    GPIO.output(OUT_INPUT_B, signal[1])

def read_state():
    Qc = GPIO.input(READ_STATE_C)
    Qd = GPIO.input(READ_STATE_D)
    Qe = GPIO.input(READ_STATE_E)
    Qf = GPIO.input(READ_STATE_F)

    code = f"{Qc}{Qd}{Qe}{Qf}"

    if code in STATE_LIST:
        return STATE_LIST[code]
    
    return FAULT_STATE_UNKNOWN

# This calls a system command to measure CPU temp
def get_cpu_temp():
    temp_result = subprocess.run(['vcgencmd', 'measure_temp'], stdout = subprocess.PIPE)
    
    # Chop out the temperature value from the stdout
    return temp_result.stdout.decode('utf-8')[5:-3]

import subprocess

def main_loop():
    time_sample = time.time()
    temperature = 38.0
    while txt := input('SIGNAL SELECT :> '):

        if txt == 'alpha':
           send_signal(SIG_ALPHA)
        elif txt == 'beta':
           send_signal(SIG_BETA)
        elif txt == 'gamma':
           send_signal(SIG_GAMMA)
        else:
           send_signal(SIG_NO_OP)

        send_clock()

        if (t := time.time()) - time_sample > 1:
            time_sample = t
            temperature = get_cpu_temp()
        
            state = read_state()
            print(f"STATE CHANGE: {state: < 20} Temp={temperature}C     ")

        time.sleep(0.1)

if __name__ == '__main__':
    try:
        main_loop()
        # Reset by pressing CTRL + C
    except KeyboardInterrupt:
        print("Measurement stopped by User")
        GPIO.cleanup()