Opto-isolator inputs configuration
File /etc/rc.local
Edit the file with this command (Inserted at the end of the file just BEFORE exit 0 )
sudo nano /etc/rc.local
#INPUTS echo "24" > /sys/class/gpio/export & sleep 2 echo in > /sys/class/gpio/gpio24/direction echo "25" > /sys/class/gpio/export & sleep 2 echo in > /sys/class/gpio/gpio25/direction echo "26" > /sys/class/gpio/export & sleep 2 echo in > /sys/class/gpio/gpio26/direction echo "27" > /sys/class/gpio/export & sleep 2 echo in > /sys/class/gpio/gpio27/direction
Tests of opto-isolator inputs
A second way is to use the distributed +5V to feed the external contact. In this case, it will be necessary to link pine 9 or 10 of connectors J26 (screenprinting OPTO INPUTS) with the mass plan. In this case, the opto-isolation is not operational because the power supply comes from the card.
The following python code allows you to check the states of each of the 4 inputs.
sudo nano test-input.py
- | test-inputs.py
#!/usr/bin/python import time from RPi import GPIO GPIO.setmode(GPIO.BOARD) GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) GPIO.setup(22, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) GPIO.setup(37, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) GPIO.setup(13, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) while True: inputval1 = GPIO.input(18) inputval2 = GPIO.input(22) inputval3 = GPIO.input(37) inputval4 = GPIO.input(13) print "INPUT1="+str(inputval1) + ",INPUT2="+str(inputval2) + ",INPUT3="+str(inputval3) + ",INPUT4="+str(inputval4) time.sleep(1)
The tests will be launch with this command
sudo python test-input.py
Here are the results of the tests for the channels 1 to 4.
CTRL-C to exit