Nucleo board USB and SDIO signal integrity

Mikk Leini · ‎2015-08-25

Posted on August 25, 2015 at 20:45

I am thinking of building several ''shields'' with GSM, GPS, LCD, MicroUSB and MicroSD connectors to stack up on the STM32F401 Nucleo board (by the dual row connectors, not Arduino) but i'm worried about the signal integrity of the USB and SDIO traces. It's a pity that ST didn't put user USB (not even connector footprint) on the Nucleo boards. So now i'm not sure at all if the USB (device) will work flawlessly if the connections go through the 0.1'' pinheaders. The headers go up and down so whether i connect my extension board bottom or top there will always be a stub on D+/D- unless i cut the other header. But nothing can be done about the non-matched impedance and other issues. I have similar worries about SDIO also.

Does anybody have experience with Nucleo board and USB/SDIO ? Or can somebody with better electronic knowledge comment this? Most secure option what i could think of is that i put USB and MicroSD on the expansion board that goes right on top of Nucleo board and i cut all the USB and SDIO pins which go further up. Would that be enough to avoid troubles?

I ordered the Chinese Waveshare XNUCLEO board also which has the user USB on main board, but unfortunately they haven't connected OTG_FS_VBUS (PA9) pin to USB VBUS :((

#nucleo-usb-sdio-signal-integrity

Tesla DeLorean · ‎2015-08-25

Posted on August 25, 2015 at 21:27

I think ST refers to that as the Morpho header

I've hung MicroSD cards off the STM32F4-DISCO headers with no ill effects.

I think there have been a couple of members who put SDIO cards on the NUCLEO's. I've personally been frustrated by the USART connectivity on the NUCELO's

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Mikk Leini · ‎2015-10-08

Posted on October 08, 2015 at 21:44

Just for the record: i created the top stackable board for Nucleo with full-speed USB and SDIO running at 24 MHz. They both work. But just in case i cut the USB and SDIO male headers of the board to stop them going upwards to the next stacked board. General USB spec said that stubs should be kept short so that's why i cut them. I don't bother checking the signals with good oscilloscope until i don't see an issue.

PS.

One more bad thing about Waveshare XNUCLEO board: SWD debug connector doesn't contain reset signal so if your SW is screwed you can't access it.