Hello,
I was trying to change Vref to read smaller voltages, but as I supply smaller voltage to the Vref pin, it's always 3.3v. I can't find anything to configure this pin or so, to be able to change it. If you have anything that may help, please let me know. Thanks, Hashem
There are no LPC2388 section. Keil don't have thousands of sections for all the possible processors. The closest you can get is to post to the ARM section. But there are huge numbers of ARM chips.
The LPC23xx chips can use different reference voltages. So next is that you have to tell exactly what electrical design you have. Are you using a specific development board, or your own design? Maybe the development board already have 3.3V directly connected to that pin, with just some filtering components to keep the reference stable?
Oh, well I guess I got confused when I first posted. Thanks for telling me.
Basically I am using MCB2300 Evaluation Board (http://www.keil.com/mcb2300/mcb2388.asp)
I am trying to read voltages that are less than 3mVolts. According to the user manual I have the reference voltage for the ADC is Vref and initially Vdd. Also the manual describes this pin to be an input pin to change the reference voltage.
the manual: (http://www.keil.com/dd/docs/datashts/philips/lpc23xx_um.pdf)
I am trying to read voltages that are less than 3mVolts. directly to an ADC, you have to be kidding
Erik
The voltage changes by factor of .5 mVolts (coming from very sensitive sensors). I am trying to see a posibility of capturing this change with changing the refrence voltage and not adding any amplifiers.
Hashem
The lowest VREF allowed for LPC23xx is 2.5V. With a 10-bit ADC, that still leaves you at 2.5mV steps (can I assume that you did check the datasheets?). So this would be a good time to stop experimenting with the voltage reference and instead condition your signal.