Custom hardware design

Hardware
#1

I designed a simple breakout board for the IMP003 to give this interesting module a try but I have had questions about requirements, many of which have been answered (Thanks Hugo!). But I notice that in section 4 of the document “Designing Hardware with the imp003” the SPI flash is shown with the WP connected to GND via a 100 K resistor. This turns on write protect, which seems wrong. Shouldn’t the WP be pulled up to VDD?

Also, there is allusion to a pcb antenna design but I can’t find the detailed antenna dimensions, so I took a guess. Similarly, many of the illustrations seem to show a pi network for antenna tuning, surely there must be some recommended values for at least the terminal capacitor (1 - 5 pF, I would think). But I can’t find any of this antenna design info. Can anyone point to a link?

I am sure once I assemble my first board and try to do something with it I will have all kinds of other questions, but one I am wondering about now is if I build a board from scratch, can I just use the blink up with a blank SPI flash memory and program the board using the IDE, or do I somehow have to load some enabling software first like with the nRF51?

#2

The /WP pin doesn’t enable protect unless the protection register enables it first, but yes IMO it shouldn’t be pulled low in most designs.

https://www.electricimp.com/docs/hardware/imp003_hardware_guide/ has general guidelines and you should copy the antenna from these gerbers: https://www.electricimp.com/docs/hardware/resources/reference-designs/impee-fcc003/

That design also has the required pi network details.

Yes, you just put a blank SPI on there. The imp will populate it on first powerup (takes a few seconds) then you can blink it up as normal.