Full size SD Card Reader Prototype

UFP needs 5.1k pull down resistor on booth CC pins to get recognized

Please can you point out where and why 4.7k is used?

Alright you win, but it only requires one 5.1k if you are using USB 2 and as a plug not a receptacle.

And they are still missing.

Hi Josh, i’m not here to compete, i would like rather work together.

If i got it right my expansion card is a UFP device, so it has to present 5.1k on CC ( i can only use A5 pin - because the expansion card can’t be rotated) pin in order that the DFP or DRP device ( in this case framework laptop) supplies 5V to UFP per Type-C spec. And i have to ensure that i don’t draw more current than 0.5A because i’m an USB2.0 device and default is 500mA. If i’m an UFP it doesn’t matter if i use plug or receptacle connector.

Please can you tell what i’m missing , and where i’m missing the 4.7k ?

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You just need a 5.1k ohm resistor on A5.


To be fair, even the TB3 SINGLE IC is very expensive ($150) as the Intel evaluation board and other cheap Thunderbolt to PCIe bridge shows. It is also a very large footprint and you wont fit it inside a expansion unit. Unless you opt for things like 6-layer PCB (which will furthermore drive up the cost)

That would be a good question to ask.
Personally I don’t own any SDIO equipment, but I know there are things like SD-card sized WLAN card and some more exotic ones like SD card-to-SATA adapters. Which uses SDIO and probably wont work without said fancy PCIe SD chip.
I think a single physical chip will be able to handle both. Some Realtek stuff …

But really. I think that if you actually own any SDIO equipment, you won’t be choosing Framework for such limited legacy support and is probably still rocking a 5th or 6th gen Intel.

A bit unrelated, but as a temporary workaround I have put together my own DIY SD card reader that fits in the expansion card bay.