Slice of PI/O
The Slice of PI/O, shown in Figure 9-3, is a small, low-cost board that provides eight buffered inputs and eight buffered outputs using the same MCP23S17 port expander as the Pi Face. It does not, however, have the Darlington driver of the Pi Face and, therefore, cannot drive high-power loads. The maximum load directly from the MCP23S17 is 25mA, which is enough to drive an LED with suitable series resistor, but not enough to drive a relay dir-
ectly. Figure 9-3 The Slice of PI/O The board takes all the I/O pins to edge connectors, and each of the 16 I/O pins can be configured as either an input or output.