Computing stuff tied to the physical world

Meet the Output Plug

In Hardware on Nov 17, 2009 at 00:01

Here is another I2C I/O plug:


It combines the MCP23008 8-bit port expander with a ULN2803 darlington array which can drive up to 500 mA @ 50V. The ULN2803 includes clamping diodes, so that relays and other small inductive loads may be tied directly to this plug.

Here is an example with a little unipolar stepper motor:


The red-black wire is from a 12V lab supply.

This demo sketch pulses the lower 4 bits of the output plug to rotate this motor back and forth by 200 steps:

Screen shot 2009-11-12 at 15.46.22.png

The above was inspired by some sample code by Chad Phillips. It has been added the the Ports library as “output_stepper” example sketch.