Legal Removal Request

Post: The IO Pi Plus only uses the two I2C pins on the GPIO port while the Expander Pi uses the I2C and SPI pins. One issue you may find combining an Expander Pi with 3 IO Pis is the voltage level translator used on the Expander Pi I2C port stops working properly if the pull-up resistance drops below 5K. Each IO Pi has a 10K pull-up resistor on the I2C line so running three in parallel would drop their resistance down to 3.3K which is below the Expander Pi limit. 4 IO Pi Plus boards should work fine in parallel and will give you 128 inputs or outputs. You could combine this with an ADC board to give you the analogue inputs. One way to increase the number of input pins would be to use multiplexers on the GPIO or IO Pi pins. Something like a [url=http://uk.farnell.com/texas-instruments/cd4512be/ic-logic-4000-data-selector/dp/1607677]CD4512BE[/url] or similar logic device would allow you to read 8 inputs using 4 pins effectively doubling the number of available inputs.