Introduction: Raspberry Pi Isolated GPIO Board With 12-24VDC to 5VDC Power Supply

By ARMTRONIX

This instruction-table will help you to setup of the Raspberry Pi with the Isolated GPIO Board.

The features of the board are

1) 12 to 24V input and output(industrial standards).

2) Raspberry Pi pin to pin matching Headers so that you can stack it on Pi.

3) Four Input and Four Output Terminal Blocks.

4) One Common Ground Terminal Block for sensor Ground connection.

5) On board 24V to 5V converter to power on pi directly .

Step 1: Details

Above image.1 shows input power supply connecter, fuse holder, P1 header for connecting to raspberry pi and input, output connecters. IN1, IN2, IN3, and IN4 are inputs (24V). OUT1, OUT2, OUT3 and OUT4 are output (24V). OUT_GND1 common ground, P1 shows raspberry pi one to one matching header.

Above image.2 Shows the P1 header pinout.
We have used eight gpio’s for four input and four output from the raspberry pi header .On the isolated gpio board, Four input gpios are:

Gpio6 -----> Pin No.31 ----->IN4

Gpio13 -----> Pin No.33 ----->IN3

Gpio19 -----> Pin No.35 ----->IN2

Gpio26 -----> Pin No.37 ----->IN1

and Four output are

Gpio4 -----> Pin No.7 ----->OUT4

Gpio17 -----> Pin No.11 ----->OUT3

Gpio27 -----> Pin No.13 ----->OUT2

Gpio22 -----> Pin No.15 ----->OUT1

DIN is output from sensor/push button and input to board.

Step 2: Ribbon Cable Connection and Wiring of Sensors ,relay ,pushbutton

Refer the pic 1 for FRC connection

Diagram 2 shows the wiring of sensor, push button and a relay.

1] Sensor A three-wire sensor has 3 wires present. Two power wires and one load wire. The power wires will connect to a power supply and the remaining wire to some type of load. The load is a device that is being controlled by the sensor. Raspberry pi isolated gpio board inputs are two terminal block where we connected sensors two wires, one is to power on the sensor and other is output of the sensor, 3 rd wire is to connect ground. Refer above image.

2] Push Button Push button has four connecting points two for input other two for output, above diagram show the connection of input and output of push button. Refer above image.

3] Relay Above image show the wiring connection of relay, we can drive motor through relay, connection of relay and motor shown in diagram, COM should connect 12/24V(depends on relay) power supply.

Also If you want complete Ground isolation and dont want to use the 12/24VDC to 5V DC on board powersupply you can do this by unmounting resistor R32, J1. This is useful in case some emi from the load is effecting the Pi

Step 3: Video of Application

First Video is an application where two 24VDC buttons are used , One for Reboot and the other one for Shutdown

For Reboot Code

For Shutdown Code

Both have to run during boot .This can be done by running a shell scrip on boot (using rc.local).

Here is an example of the script name " start_python.sh"

#!/bin/sh
# launcher.sh

# navigate to home directory, then to this directory, then execute python script

#/bin/login -f root

cd /

cd /root/Desktop/startup

sleep 30

python /root/Desktop/startup/reboot.py &

python /root/Desktop/startup/shutdown.py &

Copy the above on start_python.sh file and set permission using chmod .eg

chmod 755 /root/Desktop/startup/start_python.sh

after this go to

nano /etc/rc.local

and add this at the bottom

sh /root/Desktop/startup/start_python.sh

Second Video I am just triggering all the outputs in a particulate sequence and have connected for back lit push buttons .

Here is the Code

to run the code you will need to open terminal and type

python file name

file name here will be the name of the python script