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using_analog_reference.jpg

The folks at Little Bird Electronics have a nice tutorial about how and why to use the analog reference input on a microcontroller to improve analog voltage measurements.

Their tutorial focuses on the AREF input for the Arduino, however the technique is applicable for almost every micrcontroller with analog inputs. In fact, we’re doing something similar in the Make It Last build series, by using a fixed 2V reference to have consistent readings while using batteries that are continuously draining.


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Comments

  1. elliot says:

    Tell me how do you encode 5 voltage levels in 2 bits?

    1. Matt Mets says:

      I think the diagram is ok- there are four distinct areas that the sensed voltage can fall under:

      0v-1.25v: reads 00
      1.25v-2.5v: reads 01
      2.5v-3.75v: reads 10
      3.75v-5v: reads 11

  2. pff says:

    i really dont know how to feel about this.
    i would love to think people would just have a flip through the datasheet if they needed to do adc, and this would all be common sense to anyone who has even a flicker of understanding enough to be able to make their own useful project using the micro controller of choice.
    I guess not, since i constantly see people connect the AREF to +VCC in project that dont use adc at all. i would love to believe that all these people are just following best practice to tie unused pins stable, but i fear that is just not the case, and these people are simply clueless.
    Arduino is great for teaching some principles i guess, but if you make the hardware platform so simple that anyone can use it without any background knowledge, then i guess this is what you end up with.
    I’d like to think that maybe a few years ago this would simply not be worth of report, anyone who could use a micro controller could use it properly, had some basic background knowledge of what they were doing, course or self taught, they understood it, and could read a data sheet.
    ho-hum.