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PIC remote potentiometer

Dual remote potentiometer with PIC12C508

Circuit diagram and operation description with freely downloadable PIC-project source code


Operation principle

PIC12C508 microcontroller with software programmed two separate up/down counters with pulse width modulated (PWM) outputs.
Counters can contain values 0..32. Power-on values are zeros.

Two alternative input functions:

1. Pulsed inputting. Every close action of the UP button increases the counter value while DOWN-button decreases it. Minimum input pulse width 10 ms, maximum width 800 ms. (These values include safety reserve. Theoretically limits are min: 4 ms, max: 1 s)

2. Continuous inputting. Holding UP or DOWN button closed makes repetitive increasing/decreasing actions to the counter with 1 s intervalls.

Counting from min to max (or max to min) takes a half minute time when using the continuous inputting mode while with the pulsed inputting same action can be done withing one second.

The inputs have software controlled debounce filtering 4 ms.

Outputs are equipped with simple RC-filters to convert PWM outputs to dc level 0..5V signals.


Above are the waveforms of the PWM-outputs at several counter values. Pulses are 50 us wide. Minimum counter value is 0, when the output is continuously 0 V. Maximum counter value 32 holds the output continuously + 5 V.

Free Download of the PIC project source:
I'm sorry about mixing english and finnish in comments. Try to understand indeed :-)
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19.October .2002