On Sat, Nov 15, 2014 at 12:05 PM, David Carkeek <email@example.com> wrote:
I thought the DW1000 I/O supply could be run at 1.8V, but it can’t. It’s 2.8V – 3.6V. There are separate 1.8V-optional supply pins for digital and analog circuits (to save power) but they can run at 3.3V. So for the time being, since the nRF51822 can run at 3.3V, the whole board will be 3.3V so all the I/O’s will be 3.3V. Later we will have to determine if running the nRF51822 at 1.8V for power saving is needed, then level shifting the signals connected to the DWM1000.I assume the Segger adjusts to the proper I/O voltage by means of its Vref pin.
I’m not sure how the SEGGER knows how to adjust, but I found this bit in the SEGGER documentation.