RE: Questions about I/O ,crystal of nRF51822

wlgrd — Sun, 21 Jun 2015 20:47:52 GMT

You should mark the answer as accepted

RE: Questions about I/O ,crystal of nRF51822

John — Tue, 22 Oct 2013 00:52:44 GMT

Thank you very much

RE: Questions about I/O ,crystal of nRF51822

Håkon Alseth — Thu, 17 Oct 2013 12:12:58 GMT

Hi Alice,

The GPIO on nRF51822 can not handle more than VDD+0.3V. Example: If you're running on 3.3V, the maximum voltage on a GPIO is 3.6V.

If you use it purely as a input, I would suggest using a resistor divider. If output, use a transistor buffer. If bidirectional, then you will have to use a level shifter.

Yes, you can source the nRF-device from an active crystal. This is done by connecting it to pin "XC1" and leaving XC2 unconnected.
Yes, it will then fallback to LDO operation. However, I would strongly recommend that you read Stefan's post in this thread before designing in the DCDC: devzone.nordicsemi.com/.../ldo-vs-dcdc-nrf51822

Best regards Håkon