fvrsetup settling time

[Baker Steve]

The Microchip reference material states that once the FVR is activated, it requires time to stabilise – but fails to say for how long.

Does anyone know?

 

[Technical]

If you step into the fvrsetup like this post example the firmware processing time is generally enough without extra delays

Post in thread 'adc resolution on picaxes, down to 100mV'

Mar 1, 2023

Is it possible to program any of the picaxe micros :adc: down to as little as 50 millivolt levels ie the picaxe gives a different output for every step level change of 50mv either up or down..?

Years ago I delved deeply into why the manufacturer of the base chip said not to do this, and never got a satisfactory answer. However, there is an errata sheet that says if you DO use a lower internal reference voltage, you should "step in to it", rather than invoke it in one fell swoop. Using the internal 1.024 volt reference lets you discriminate 1 millivolt per step on a 10 bit ADC like...

• rq3

 

[Baker Steve]

Thanks. But I don't understand what Microchip mean by 'step into it'. What is your interpretaton?

 

[Technical]

Stepping down means using 3 commands, fvrsetup FVR4096 then a 2048 then a 1024, rather than just a single 1024 command.