Hi, I want to know how I can connect an external reference voltage for my STM32F407. The internal reference voltage is at 3.3 volts and my input goes beyond that voltage to about 5 volts. When I feed the 5 volts as input to my microcontroller, I get a wrong reading. So, I want to change the reference voltage to 5 volts using an external source. How do I do that?

 

"Normally" there is a register reference manual on processors, but
I cannot seem to find one online. Lots of manuals, ap notes, even
on ADC but none seem to cover Vref setup.

Maybe contact their FAE or post directly on their support website
if no one else posts on his thread.

Regards, Dana.

 

I had a very quick look at the manual RM0090. You can't do it.

VDDA must be less than or equal to VDD and VREF must be less than or equal to VDDA.

 

Asleep at the switch on this one, ebp correct, so you would use a voltage
divider at input and account for that in code.

Regards, Dana.

 

Asleep at the switch on this one, ebp correct, so you would use a voltage
divider at input and account for that in code.

Regards, Dana.

Thanks. I'll try that out.