The Slice of Pi/O is an I2C expansion board for the Raspberry Pi.

The Slice of Pi/O may be configured in 3V3 or 5V modes of operation via a jumper.

Power may be taken from the board on PWR and GND if a suitable 4-pin header is fitted.

sed -i 's/^blacklist/#blacklist/g' /etc/modprobe.d/raspi-blacklist.conf

echo "device_tree_param=i2c1=on" >> /boot/config.txt

echo 'SUBSYSTEM=="i2c-dev", MODE:="0666"' >> /etc/udev/rules.d/10-local.rules
echo "options i2c_bcm2708 baudrate=400000" >> /etc/modprobe.d/modprobe.conf
echo 'i2c-dev' >> /etc/modules
reboot

For the MCP23017 a baudrate of 900000 has been tested and appears to work satisfactorily. You should experiment with this value.

Low Voltage Programming with VPP at 3V3 or 5V

Separate data I/O connections (only supported option)

SLICE OF Pi/O                     PICMicro
=============                     ========

PWR-------------------------------VDD

GND-------------------------------VSS

A0--------------------------------VPP

A1--------------------------------PGC

A2--------------1000R--------+----PGD
                             |
A3---------------------------+

A4--------------------------------PGM (1)

1. Not used by all LVP compatible devices.