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Three Output States from One Pin

See this thread for the original discussion/design of using one pin,set to High,Low or Hi Impedance to generate three output states to allow control to two outputs. Handy if you are short 1 pin. Initially used on the Picomite to use a single pin to control both Touch CS and SD CS on an LCD Panel.
A new Pico PCB for V5.09.00 - comments

The Truth Table

Pin Status Output 1 Output 2
HiZ (set as input) 1 1
0 (set as output) 0 1
1 (set as output) 1 0

The circuit (courtesy @Turbo46 on TBS)
Note1: The symbol for Q3 is incorrect, should be an NPN the same as Q2
Note2: Change all 10K to 1K and all 100K to 10K

The circuit works when you change Q3 into an NPN transistor. Works perfectly. I've substituted 1k for all 10K and 10K for all 100K Three output states from one pin www.thebackshed.com_forum_uploads_matherp_2024-02-14_220010_pxl_20240210_191321546.jpg


circuit_ideas/three_output_states_from_one_pin.txt · Last modified: 2024/03/04 08:58 by gerry