The hardware hackers interface for the Raspberry Pi

1. CUSTARD PI 7
ADVANCED INFORMATION
The Hardware Hackers Interface for the Raspberry Pi
19th Nov 2013
SF Innovations

2. OVERVIEW OF FEATURES
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2 Relay outputs
4 Open Collector outputs
2 Built in Switches
8 General Purpose Digital I/O
4 Analogue inputs
1 Analogue output
16 pin LCD Interface
LED indication on most ports
Screw terminal connection on most ports
Flexible Power Supply
Board can be powered from Raspberry Pi
Board and Rpi can be powered from 5V supply
Board and Rpi can be powered by 2 separate 5V supplies
LED indication of 5VPi, 5V and 3V3 supplies
Fused 5V and 3V3 available on screw terminals
Prototyping area with pads for 14-pin SMT IC
Ribbon Connector (26 way) to the Raspberry Pi GPIO
Second Connector (26 way) to daisy chain a second Custard Pi -7

3. LAYOUT OF COMPONENTS
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This PCB board size 15cm x 11 cm

4. PROTOTYPING AREA
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5. RELAY AND OPEN COLLECTOR OUTPUTS
This is provided using the MCP23008 8-port I/O expander which works
on the I2C bus.
The 2 spare pins of the MCP23008 are used for the 2 key inputs from the
on board switches.
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This is followed by the Darlington Driver, the ULN2801 which drives the
relays and provides the 4 Open Collector Outputs. There are 6 LEDs
which indicate the status of these outputs.

6. LCD INTERFACE
This is provided using the
MCP23008 8-port I/O expander
which works on the I2C bus.
The functions to drive the display
will be provided on the www.sfinnovations.co.uk website.
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A 2 x 16 character display has a
16pin connector on a 0.1 inch
pitch and can easily be connected
to the Custard Pi 7 with a ribbon
connector.

7. 8 GENERAL PURPOSE DIGITAL I/O
This is provided using the MCP23008 8-port I/O expander which works
on the I2C bus.
The functions to control these I/O will be provided on the www.sfinnovations.co.uk website.
www.sf-innovations.co.uk

8. 4 ANALOGUE INPUTS AND ANALOGUE OUTPUT
This is provided using the PCF8591 8-bit AtoD DtoA convertor which
works on the I2C bus.
The functions to control these I/O will be provided on the www.sfinnovations.co.uk website.
www.sf-innovations.co.uk

9. POWER MANAGEMENT
There are 3 powering options.
#2 Both can be powered from the board
5V. Same as above but make sure that
only the board 5V is plugged in.
#3 Both are independently powered. In this
case make sure that jumper on J14 is on
right hand side.
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#1 The Rpi and the Custard Pi 7 can both
be powered from the Rpi 5V supply. In this
case jumper J14 is on the left hand side
and the board 5V and the Rpi 5VPI are
both connected together. Make sure that
only the Rpi 5V supply is connected.

10. POWER CONNECTORS
There is a 3-way ground connector provided.
The 3V3 and 5V supply outputs on the screw terminal are fused at 100mA
to prevent users from taking too much power from these rails.
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11. The Custard Pi 7 provides Raspberry Pi hardware hackers with a handy
board that is packed with features.
Blog dedicated to electronics & Raspberry Pi
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Further information