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Put the scope on the PWM output & hooked up the display. The wave form went really strange so I hooked the scope straight to the sender wire without the LCD display.
With the ignition on, there is a square wave present on the sender wire.
It has an amplitude of 3V at full and down to an amplitude of 1.8V at empty.
The frequency is approximately 230Hz.
I think this is the reason the gauge is not working with the current PWM.
The gauge still works fine with the trim pots though. Maybe a digital potentiometer driven by the PWM?
I am starting to think that using my custom LED gauge may be easier. It is a series of LEDS driven by an LM3914. It was originally going to reference the pack voltage via a voltage divider down to 3.2V.
I can probably drive it with the PWM output & an RC filter instead.
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