PMOD Adaptation

A project log for FUSBee5

FPGA module featuring an ECP5, dual Hyperram, USB 3.0 and 48 IOs.

KnusperkeksKnusperkeks 07/12/2020 at 21:370 Comments

In order to do some more useful experiments I finally designed a breakout board with PMOD  connectors. Both PMODs on the sides are standard ones with 3.3V or 5V (selectable by a jumper). The header on the bottom is a double PMOD in the ULX3S style with 40 pins in total, which is a very clever and nice idea. Thanks to the Radiona folks!

For ease of use and accessibility the headers (especially left and right) should be 90° angled (but the silkscreen for the straight ones is less crowded so I used it here). On the top are 4 additional LEDs for status indications. All signal traces are routed over a solid gnd plane, but without any length matching and impedance consideration (on 2 layers...yeah...).

I thought, the 2x40 pin Bergstak connector has an equal footprint for plug and receptacle and was nearly right. The only little detail is, that the two positioning pins on the bottom are of different diameter and if you would read the drawing very careful, you could recognise the need for a 180° rotation. Or just get the drill out and fix it...preferably before you soldered both connectors to the pcbs and try to mate them! ;)

With a specification of 100 mating cycles these were one of the better 0.8mm pitch connectors I found and they are available in many pin counts, heights and even a lower cost version. → Not bad at all :)
The suggested footprint in the datasheet can be used for handsoldering.

Current status of the FUSBee5 board:

Short term plans: