RTS5170 - only on ebay/ali, and can't find datasheet - Page 1
Forum section: electronics / projects

author: marcosscriven
author_rank: Contributor
timestamp: June 18, 2023, 11:10:54 am
content: I'm trying to create an EMCC to USB adapter - I appreciate there's already lots of solutions, but none quite fit what I need. In case it matters, those requirements are1.8V logic level - because it's in circuit being driven at that levelworks in 1-bit mode - because only DAT0 is accessible on the board I'm targettingexposes CLK/CMD/DAT0 - so I can wire from the board to the adapterUnderstands special EMMC boot partitions - this the reason basic emmc->sdcard adapters don't work for my purposesIn looking for SDcard readers that *can* understand EMMC boot partitions (rather than just exposed the main region as FAT32), I found the RTS5170 chipHowever, I can't for the life of me find the datasheet, by Googling "RTS5170 pdf" or "RTS5170 datasheet". There's the RTS5169, but not the RTS5170.Also, I can't find this chip on Realteks site, and it's not on any of the major suppliers' sites.It does somehow seem to be on Ali/ebay, so I've no idea if that's trustworthy, or if there's a more modern equivalent?

author: magic
author_rank: Super Contributor
timestamp: June 18, 2023, 02:26:41 pm
content: Linux has a driver for RTS5129, RTS5139, RTS5179 and RTS5170 called rtsx_usb. You could use it for inspiration to write your own driver or simply use Linux.For a one-off build, those chips could be harvested from laptop SD card modules, which are plentifully and cheaply available from e-waste recyclers. You need to find a laptop model with the chip you are after.I have a nice board for Lenovo G500 G505 G510 laptops which contains one of those chips (sorry, forgot which one) because it's the only USB SD card reader I know which exposes full SD command interface to Linux and isn't just a standard mass storage device.BTW, if anybody would like to use such a board as a card reader, beware that it needs 3.3V power rather than 5V as is standard on USB. I bodged a suitable LDO onto mine. Without this, 5V would be applied to cards.

author: magic
author_rank: Super Contributor
timestamp: June 18, 2023, 02:56:51 pm
content: The Lenovo G500 SD card daughterboard is precisely RTS5170.It has also occurred to me that you likely want the datasheet for things like pinout rather than command interface and writing driversThe board still isn't the datasheet, but it could serve as a reference design at least.With Realtek it's possible that the chip was never really available to anyone but large computer OEMs, so Chinese surplus or recyclers may actually be the only options for acquiring it. Some Chinese vendors may also be dishonest recyclers, you never know with those aholes. The IC may be discontinued by now and I don't know of other such chips. Most everybody these days seems to be selling mass storage SD readers because they don't need special drivers.

author: marcosscriven
author_rank: Contributor
timestamp: June 18, 2023, 03:28:29 pm
content: Quote from: magic on June 18, 2023, 02:56:51 pmThanks - yes, exactly - I was looking for both pinouts, as well as making sure what the recommended pull ups, caps etc. were. Plus it's clear from some boards there are in built regulators.I did find one board that uses thishttps://github.com/ignasurba/mmcblkNXHowever, they use a 3.3V LDO on there, whereas as they don't for the 1.8V. It just bugs me working blind.But I see what you mean about it maybe being only for OEMs originally.One other options I've mooted is an RP2040, which with PIO can do SDIO at a reasonable speed. However, there'd be a lot of work to get it to do more that mass storage.Yet another option was using this level shifter:https://shop.exploitee.rs/shop/p/low-voltage-emmc-adapter- but that takes ages to deliver, and I'm still left with solving the SDIO problem.The RPi SD readers do indeed work via SDIO, but the main one doesn't seem to like 1-bit, and the extra one will need wiring up.Overall I felt spinning up something that combined all these things was the best bet (short of taking the EMMC of the target, which I only want to do as a last resort).