Dewbly voltage => 3v3

Posted on by crackingcontraptions_3voi0v
On Sat, Nov 15, 2014 at 12:05 PM, David Carkeek <dcarkeek@gmail.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.

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I’m not sure how the SEGGER knows how to adjust, but I found this bit in the SEGGER documentation.

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David:

Jtag:                                                              SWD:

Inline image 1             Inline image 2
Wire for SWD, correct?
Can you look on your board to see what pins I used on the module for SWO and RESET? Or maybe just take a picture and send it to me.
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Mik:
I think we should configure it for SWD. I have not yet used JTAG on the Dewbly, and I seem to be able to do everything I wanted to do with SWD… so far anyway.

I described all the connections we used on the Dewbly on p43-44 of this document. I just tested it out again, and it works fine. Please tell me, or better still amend the document if there is anything missing or wrong. In a few months I won’t remember all the details.

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