Voltage Reference

Created Wed, 22 Jun 2011 12:10:38 +0000 by ex2939

ex2939

Wed, 22 Jun 2011 12:10:38 +0000

Hi!

I'm working with the chipKit Max 32 that has a voltage reference of 3.3V. I want to change it to 5V. How can I do it ? I tried to use the analogReference(), but does not work.

Thanks.

hairymnstr

Wed, 22 Jun 2011 14:17:48 +0000

According to the datasheet [url]http://ww1.microchip.com/downloads/en/DeviceDoc/61156G.pdf[/url] the +Vref and analogue input pins are NOT 5V tolerant so I don't think you can make the onboard ADC work with a 5V reference.

You'll need some external signal conditioning or an external 5V ADC chip.

GeneApperson

Fri, 24 Jun 2011 19:17:32 +0000

Correct... The absolute max voltage on any analog capable pin on a PIC32 part is 4V. That is the reason for the clamp diodes and current limiting resistors on all of the pins on PORTB. The digital only pins are 5V tolerant.

Mark

Sat, 25 Jun 2011 01:58:25 +0000

The analogRefence command does not do anything at this point. If we get figured out how it should behave, then I will change it.

Mark