FEDEVEL
Platform forum

mostafa222 , 10-19-2021, 11:39 PM

Hi Dear Robert.
I Have two MMC Socket that i want to connect them to MMC Port Of Microcontroller like below picture.
at one moment, only one socket is used. i have two question
1. what topology should i use to draw pcb so i did not loose speed?(T Branch or FlyBy or ...)
2. where should i place pull up resistors(at the end side of one of socket or i must place pull up resistors for each socket)?

qdrives , 10-21-2021, 05:17 PM

First simple question: what are the distances?

mostafa222 , 10-22-2021, 12:40 AM

From micro to each socket, 3 cm

robertferanec , 10-23-2021, 01:44 AM

Not an ideal situation. However, if I would have to, I would use fly-by and I would place the one which will be used more and has higher speed as the second one. Still I would try to keep the distance between the pads of the first socket and pads of the second socket very short (e.g. maybe I would place them on the top of each other). If termination resistors are required I would place them at the end of the tracks (behind the last socket).

mostafa222 , 10-24-2021, 10:50 PM

Thanks so much

ibocakir06 , 10-25-2021, 10:16 AM

I would not do this as you talked about above.

You should use an SDIO switch/multiplexer.

robertferanec , 10-25-2021, 10:35 AM

- @ibocakir06 is right, that would be the proper and best solution