RP2040 hardware design document - minor suggestions

[pdw-mb]

I have a few very minor suggestions for the RP2040 hardware design document:

• The schematic for the minimal board includes an additional 10uF capacitor (C17) that is not mentioned in the text. It would be good to explain why this is there, if it is needed in addition to the 10uF capacitor on the regulator output, and if there are any constraints on its positioning.
• Section 2.3 provides some useful information on crystal selection. The suggested crystal has a max ESR of 50 ohms, but I've struggled to find 12MHz crystals with this specification, particularly in a smaller package. Crystals with a max ESR of 80 ohms seem much more readily available. Any additional comments on how R5 should be adjusted for crystals with a higher ESR and/or what issues to look out for when using a higher ESR would be very helpful. My limited experience is that an 80 ohm ESR seems to work just fine with the suggested 1K resistor, but I don't know what issues I should be looking out for.
• Section 3.5, just above figure 25 "how do we attached the Raspberry Pi Pico" should be "attach"

I should add that this is a really excellent document. My PCB design experience is limited to what I did at school 25 years ago, and this document enabled me to successfully transfer my Pico-based prototype onto a custom PCB on the first attempt.

[lurch]

~ping @dp111~

[aallan]

This is talking about the Hardware Design book for RP2040, so not @dp111. Mike wrote it.

[lurch]

Ooops, sorry!