barone.patr...@gmail.com wrote: > [-- text/plain, encoding quoted-printable, charset: UTF-8, 17 lines --] > > I would like to use the BBB to measure the voltage on two battery banks > (12V and 24V). The batteries can go well above the nominal voltages however > to 15 and 30 volts at max respectively. In addition to using a resistive > voltage divider to step down the voltages to the 1.8V required by the ADC > is there a way to ensure that the voltage never excedes 1.8? I've been > reading around about zener diodes and it seems like they would work, but > I'm not quite sure about the implementation. Any advice? > I puzzled over this for quite a while, in the end I used low-power, low-voltage OP amps running from the 1.8 volt reference output on the BBB. The ones I have used are LM10CN which take a minsicule current (so work OK even though the reference output isn't really supposed to supply current) and have inputs which can stand up to 40 volts. This guarantees that you can't overdrive the ADC input.
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