First, thank you to our supporters!

NRFICE has surpassed our funding goal in the first two weeks of the campaign, and continues to gather support. For this we can only thank our supporters!

Corrections to The Design

Just to bring you all along with the details of the project, I’d like to use this week’s update to explain a design error that was missed in the first prototype build.

NRF5340 Special Pins for the LFXTAL on the Fanstel BT40F

The nRF5340 is the MCU on NRFICE. However, for convenience and to help with FCC/CE certification, we chose to mount the Fanstel BT40F module, which is an SMD mountable board with the nRF5340 and the required additional parts to operate and drive the antenna. When designing with the nRF5340, as with other Nordic Semi parts, it is optional whether to include an external 32.768kHz crystal. According to Fanstel’s product descripti0n, the BT40F does in fact integrate the 32.768kHz crystal, which we implemented in our design.

One ramification of this design choice is that two pins, P0.00 and P0.01 of the MCU, cannot be used for GPIO. In fact, connecting these pins to other circuitry will disable the 32kHz crystal function causing a debugging challenge.

However, in our original design, P0.00 and P0.01 were connected to the FPGA and to the expansion header.

The issue is now corrected, we have reworked the boards and tested to make sure we fixed the problem properly. To keep the ability to probe the two nets, we simply added a do-not-load resistor.

Thanks Again, Stay Tuned

Thank you to our supporters for making the NRFICE campaign a success! We look forward to completing the campaign and shipping our first production run. Stay tuned for next week’s update.