prevent script running twice consecutively - Python

Question

I have the following two Python scripts one sends a motor forward while the other script sends it backwards. Each script is operated by it's own button on a remote.

Script A

import RPi.GPIO as GPIO
from time import sleep
import json
GPIO.setmode(GPIO.BOARD)
GPIO.setup(22,GPIO.IN,pull_up_down=GPIO.PUD_UP)
GPIO.setup(19, GPIO.OUT)
GPIO.setup(21, GPIO.OUT)
GPIO.setup(23, GPIO.OUT)
abort = False
counter = 0
# read config
try:
 with open('config.json') as readfile:
 data = json.load(readfile)
 if data['lastrun'] == 'scripta':
 print('scripta already run')
 abort = True
except:
 pass
data = {'lastrun': 'scripta'}
if abort:
 quit()
print('turn motor clockwise')
pwm=GPIO.PWM(23, 100)
pwm.start(0)
GPIO.output(19, False)
GPIO.output(21, True)
pwm.ChangeDutyCycle(35)
GPIO.output(23, True)
sleep (0.5)
while True:
 input_state = GPIO.input(22)
 if input_state == False:
 counter = counter + 1
 print counter
 if counter == 2:
 GPIO.output(23,GPIO.LOW)
 exit()
 GPIO.cleanup()
 sleep (0.3)
pwm.stop()
# write config
with open('config.json', 'w') as outfile:
 json.dump(data, outfile, sort_keys=True, indent=4)
GPIO.cleanup()

Script B

from time import sleep
import RPi.GPIO as GPIO
import json
GPIO.setmode(GPIO.BOARD)
GPIO.setup(22,GPIO.IN,pull_up_down=GPIO.PUD_UP)
GPIO.setup(19,GPIO.OUT)
GPIO.setup(21,GPIO.OUT)
GPIO.setup(23,GPIO.OUT)
abort = False
counter = 0
# read config
try:
 with open('config.json') as readfile:
 data = json.load(readfile)
 if data['lastrun'] == 'scriptb':
 print('scriptb already run')
 abort = True
except:
 pass
data = {'lastrun': 'scriptb'}
if abort:
 quit()
print('blind going up')
GPIO.output(19,GPIO.HIGH)
GPIO.output(21,GPIO.LOW)
GPIO.output(23,GPIO.HIGH)
while True:
 input_state = GPIO.input(22)
 if input_state == False:
 counter = counter + 1
 print counter
 if counter == 2:
 GPIO.output(23,GPIO.LOW)
 exit()
 GPIO.cleanup()
 sleep (0.3)
# write config
with open('config.json', 'w') as outfile:
 json.dump(data, outfile, sort_keys=True, indent=4)
GPIO.cleanup()

The scripts include code designed to prevent a script running twice consecutively. Having run script A when I try to run it again it aborts as it should. Then I run script B which is fine however it doesn't abort on a second button press for some reason indicating that perhaps it isn't writing to the file as it should.

Many thanks!

Answer 1

How about using a config file to store the last run script:

scripta:

# scripta
import json
abort = False
# read config
try:
 with open('config.json') as readfile:
 data = json.load(readfile)
 if data['lastrun'] == 'scripta':
 print('scripta already run')
 abort = True
except:
 pass
data = {'lastrun': 'scripta'}
if abort:
 quit()
print('turn motor clockwise')
# write config
with open('config.json', 'w') as outfile:
 json.dump(data, outfile, sort_keys=True, indent=4)

scriptb:

# scriptb
import json
abort = False
# read config
try:
 with open('config.json') as readfile:
 data = json.load(readfile)
 if data['lastrun'] == 'scriptb':
 print('scriptb already run')
 abort = True
except:
 pass
data = {'lastrun': 'scriptb'}
if abort:
 quit()
print('turn motor anti-clockwise')
# write config
with open('config.json', 'w') as outfile:
 json.dump(data, outfile, sort_keys=True, indent=4)

• Nick C: thanks. This sounds like what I am looking for. I edited the question to hopefully make it clearer but it seems that what you have provided should do the job. Just need to study it a little as I'm not familiar with the procedure. If it works I will mark your answer as the solution. Thanks!
• CoderMike: How does the remote button work - is it connected to the Pi?
• Nick C: Yes it is. The idea is to prevent anything happening if the wrong button is pressed. It also solves the problem of double presses though I suspect that latter could be achieved within lirc itself.
• Nick C: I will mark this as solved anyway as I'm sure it is. Just not sure I will have the chance to test it today.
• CoderMike: So I assume there are 2 buttons - why not just use one python script - would be much simpler? If so post your existing code.