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