> What you're talking about does not make any sense. an ADC measures > voltage. ADC's do not have sensors connected to them. >
Sorry, I probably have not phrased my use-case clearly enough... I'm connecting sensors to the ADCs. These sensors change their resistance when sensing something. So I want to measure the voltage over the sensors using the ADCs. The sensors need 5V power to operate, but provide separate pins for measuring their resistance. On Arduino I was simply using the 5V rail to power the sensor and feeding the measurement pins, which obviously wouldn't be such a good idea on the BBB (as the OP has nicely demonstrated ;) ). A resistor-based voltage divider seemed a bit wasteful to me since quite some power goes straight into heat just for the sensors. Hence the idea to use a switching DC-DC converter for the measurement circuit. > ADCs can use op-amps ( I suppose ) to scale input voltages to except-able > levels for a given ADC. > Yes and I was wondering how to achieve this, especially how to scale _down_ a voltage using an op-amp, i.e. from 5 V to 1.8 V, since this is what's required for the OP's problem if I'm not mistaken. So far my understanding of an op-amp was that it could scale voltage up (hence the amp part of it's name). But as I said, I'm keen to learn and any pointers to suitable sources of information are greatly appreciated. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/091f2850-db68-4b03-865c-eb86a869125d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
