PIC16F628A the Voltage Reference (VRCON) anybody using it?

[William At MyBlueRoom]

The PIC16F628A has a 16 stage Voltage Reference (VRCON). I've wondered if it can be used as a D/A for a speaker. How fast is it? How much current does it source?

Might be fun to build a text to speech SPO256-AL2 type device.

 

[Jay.slovak]

I have experimented with PICs voltage reference, and it could serve as a primitive D/A.
It's drive capabilites are very bad, OPamp is necessary. (You can't even connect LCDs contrast pin directly to it). I think that it could serve as a good fast , low resolution D/A, but I doubt it can be used for tone generation (PWM would work perfectly). Keep in mind that it's output is not rail-to-rail, and is affected by VDD noise and instabilty.

 

[Pommie]

I used it in conjunction with one of the comparators to measure the voltage of a 12v battery that was powering the circuit. A 9.1V zener got it into the right ball park and then by adjusting VRCON and checking the comparator you can work out the main battery voltage. Not very accurate but good enough for a battery low indicator.

Never tried it the other way around.

Mike.