This PowerPoint presentation shows how to use the built in I2C process of the Raspberry Pi Linux Operating System to do the same thing.

1. CUSTARD PI 6 & I2C
USING THE RASPBERRY PI I2C UTILITIES
8 Relay card with ribbon connector and I2C bus interface
18th Nov 2013
SF Innovations

2. FUNCTIONS FOR CONTROLLING THE CUSTARD PI 6
RELAY CARD
Original set of Instructions
This PowerPoint presentation shows how to use the built in I2C process
of the Raspberry Pi Linux Operating System to do the same thing.
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In an earlier instruction we showed how to control the Custard Pi 6 8relay card using the functions provided in cpi6.py routine. This used “bit
banging” to provide a basic I2C bus serial interface to address the
Custard Pi 6 board and switch relays ON and OFF.

3. CUSTARD PI 6 - FEATURES
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4. CUSTARD PI 6 - ADDITIONAL DETAILS
To Custard Pi 6
Notch to the right
The 12V adaptor to supply the Custard Pi 6 is NOT
supplied. This can easily be purchased on Amazon or EBay.
Spec: 12V DC, 1 Amp
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To Raspberry Pi
Notch to the right

5. GPIO CONNECTIONS
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Only 4 pins used
3.3V and 0V to power the I2C chip and driver
&
I2C SDA and SCL pins

6. USING THE CUSTARD PI 6
We supply a set of routines to make it very easy to control the Custard Pi
6.
Just download the file “cpi6x.txt” and place this in the same directory as
the program that you are developing. Rename it as “cpi6x.py”.
Addressing the board
You can use up to 8 different Custard Pi 6 boards to control a total of 64
relays.
Use switch S1 to set the address of the card that you are using.
Download cpi6 control cpi6x.txt
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Then just use the following commands to control each individual relay on
the card.

7. USING SWITCH S1 TO SET THE ADDRESS
S1 pos 2 S1 pos 3 S1 pos 4 Address
ON
ON
add0
OFF
ON
ON
add1
ON
OFF
ON
add2
OFF
OFF
ON
add3
ON
ON
OFF
add4
OFF
ON
OFF
add5
ON
OFF
OFF
add6
OFF
OFF
OFF
add7
Position 1 is not used.
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ON

8. SETTING UP THE I2C BUS – STEP 1
At the command prompt type:
sudo nano /etc/modules
Add the following two lines to this file
i2c-bcm2708
i2c-dev
Then save and exit the file using CTRL-x and Y.
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This uses the nano editor to make some changes to the modules file.

9. SETTING UP THE I2C BUS – STEP 2
Make sure that you have the I2C utilities installed by executing the
following two commands. The Pi will need to be connected to the Internet
for this.
If you get a 404 error do an update first:
sudo apt-get update
Note : The installation could take a few minutes to do, depend on how
busy the server is.
Now add a new user to the i2c group:
sudo adduser pi i2c
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sudo apt-get install python-smbus
sudo apt-get install i2c-tools

10. SETTING UP THE I2C BUS – STEP 3
On the Raspberry Pi, the I2C and the SPI buses are usually disabled.
This is done in the /etc/modprobe.d/raspi-blacklist.conf file.
sudo nano /etc/modprobe.d/raspi-blacklist.conf
If the I2C and the SPI is blacklisted, you will see the following commands.
blacklist spi-bcm2708
blacklist i2c-bcm2708
Insert a # in front of these to comment them out.
Then save and exit the file using CTRL-x and Y.
After editing the file, you will need to reboot for the changes to take
effect.
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If this file is not present then there is nothing to be done. Otherwise edit
the file by typing the following at the command prompt.

11. SETTING UP THE I2C BUS – STEP 4
Now we need to test if the I2C bus is working correctly.
Connect up the Custard Pi 6 board (or any other I2C bus device) and run
the following command.
Or
sudo i2cdetect -y 0 (for Rev 1 boards which uses port 0)
If everything is OK, then the I2C address of the device will be shown as
on the following slide.
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sudo i2cdetect -y 1 (for Rev 2 boards which uses port 1)

12. SETTING UP THE I2C BUS – STEP 4
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I2C devices with address 40 and 70 present on the bus.

13. USING THE CUSTARD PI 6
First, set all the pins to be as outputs by using the following command.
board1=cpi6x.add1
cpi6x.setasoutput(board1)
cpi6x.setbit(board1, cpi6x.ONrelay0)
The following command clears relay 0 on board 1 – ie turns it OFF
cpi6x.clrbit(board1, cpi6x.OFFrelay0)
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The following command sets relay 0 on board 1 – ie turns it ON

14. PYTHON PROGRAM
This program sets
relays 0,1&7 on
board 1 ON and then
turns them all OFF
again.
This is done
continuously until
the program is
aborted by a CTRL C.
When testing, please
make sure that
switch S1 is set
correctly for add1.
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#1/usr/bin/env python
import RPi.GPIO as GPIO
import time
import cpi6x
GPIO.setmode(GPIO.BOARD)
#start program
board1=cpi6x.add1
cpi6x.setasoutput(board1)
while True:
cpi6x.setbit(board1, cpi6x.ONrelay0)
cpi6x.setbit(board1, cpi6x.ONrelay1)
cpi6x.setbit(board1, cpi6x.ONrelay7)
cpi6x.clrbit(board1, cpi6x.OFFrelay0)
cpi6x.clrbit(board1, cpi6x.OFFrelay1)
cpi6x.clrbit(board1, cpi6x.OFFrelay7)
GPIO.cleanup()
import sys
sys.exit()

15. Blog dedicated to electronics & Raspberry Pi
Custard Pi 5 available from stockists
Up-to-date info on stockists on website
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Further information