IO expansion

enrico.migchels — Thu, 07 Oct 2021 04:55:45 GMT

Current Revision posted to Documents by enrico.migchels on 10/7/2021 4:55:45 AM

When the number of pins on your programming device run out, you might consider upgrading to a bigger device. In stead of this 'easy way out' you can consider adding more functions to 1 pin.

Expanding a programming device with an extra output is possible when an extra level to an output is added ('0', floating and '1'). The floating state can be made if the pin is defined in your running code as 'input' (an external resistor divider will define the floating voltage).

In the schematic below the 3 states on pin 2 of the controller will do the following:

'0' : T1, T2 deactivated.

'floating' : T1 on, T2 deactivated.

'1' : T1 and T2 on.