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Topic: Can 5V be put into an analog pin with 1.1v ref. ? (Read 421 times) previous topic - next topic

sparkylabs

I want to make a circuit for PWM control, i have a hand controller that will be controlling it and I think the easiest way to get good linearity is to put a larger resistor in series, the resistance of the controler is 0-60 ohms, with with a 1K resistor in series the resistance total would vary by 6% so would stay pretty linear, this would mean very poor resolution though so ideally I'd need to power the two from a higher voltage to get the voltage range up - or drop the measured range to match the outputted range. 1.1V ref with 5V supply is a good starter point. But it means that when the 0-60 resistor becomes disconnected which it does with the trigger at rest the ful 5V would go into the micro, will this be a problem with the micro powered from 5V ?
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Grumpy_Mike

#1
Jun 23, 2013, 08:02 pm Last Edit: Jun 23, 2013, 08:55 pm by Grumpy_Mike Reason: 1
No problem putting 5V into an analogue pin no matter what the referance, it will however read 1203 1023 like all voltages above the reference.

CrossRoads

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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sparkylabs

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Grumpy_Mike

It is not off the scale it is the top of the scale.

sparkylabs

well 5V is off the scale for a 1.1Vref and will give 1023 by default so I'll take anything over 1000 as my mark
My shop: www.sparkylabs.co.uk/shop

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