generating potentiometer adjustable, non-inverted voltage square pulses from microcontroller gpio output

Question

I would like to generate a square signal with SW adjustable duty cycle, phase etc using the output pin of a microcontroller (3.3V). Frequency <100Hz. However, I also want

1. the amplitude of the high state to be in ~ 2-7V range adjustable with a trim potentiometer from a 12V supply rail,
2. When the signal is low it should be close to zero.
3. no spikes or disconnected states between transitions to high/low
4. signal to be zero when the microcontroller output is zero (non-inverted).

The signal will be fed into high impedance op-amp inputs which will driveflash/strobe circuits, so it is like a common analog input signal to multiple strobe circuits. What is the simplest way to do this? A mosfet, analog switch IC or ?

Thank you!

Answer 1

Another option is simply an N-MOSFET. 99.9% of the time you can do the inversion in the MCU itself and remove U1, but on the off-chance that you can't for whatever reason, add an inverter U1. Also, restrict your pot range by adding lower and upper fixed resistors:

^{simulate this circuit – Schematic created using CircuitLab}

An even simpler option is to replace both the inverter and the MOSFET with an open-drain (or open-collector) 12V-tolerant non-inverting buffer.

Answer 2

I would use an analog mux. You require "no spikes", this is a vague requirement, but a fast analog mux should meet your needs.

Depending on which analog mux you choose, you may need a level shifter.

^{simulate this circuit – Schematic created using CircuitLab}

Answer 3

here's another, not particularly precise, but just for variety. pot is 7K. falstad link