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

=== Power ===
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.

=== RPi I2C ===

== Without device tree ==
<code>
sed -i 's/^blacklist/#blacklist/g' /etc/modprobe.d/raspi-blacklist.conf
</code>

== With device tree ==
<code>
echo "device_tree_param=i2c1=on" >> /boot/config.txt
</code>

== With and without device tree ==
<code>
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
</code>

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

=== I/O ===
^RPi revision	^I2C device	^Default MCP Address|
| 1		|/dev/i2c-0	|0x20|
| 2		|/dev/i2c-1	|0x20|

=== Pickle Microchip PIC ICSP ===

Low Voltage Programming with VPP at 3V3 or 5V

Separate data I/O connections (only supported option)

==Wiring==

<code>
SLICE OF Pi/O                     PICMicro
=============                     ========

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

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

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

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

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

A4--------------------------------PGM (1)
</code>
   - Not used by all LVP compatible devices. 

==Config==
<code>
VPP=0     # A0
PGC=1     # A1
PGDO=2    # A2
PGDI=3    # A3
PGM=-1
DEVICE=MCP230XX
IFACE=/dev/i2c-1
ADDR=0x20
SLEEP=0
#VPP_RUN + PGD_IN_PULLUP
BITRULES=0x1010
</code>
===Resources===

[[https://wiki.kewl.org/downloads/Slice_Pi.pdf|Assembly manual]]