I'm trying to use an M2-to-SATA adapter to connect a 2.5" ssd to the M2 slot (I already have the ssd lying around and I'm planning to use the on-board SATA port for another disk). I got one of these: http://www.iocrest.com/en/product_details546_a.html The Udoo x86 user manual says the m2 slot supports both SATA and PCIe. However, I can't get Udoo x86 to see the disk (neither from the boot menu of the BIOS configuration, nor from a linux distro booted from usb). This is my current setup (having disconnected all non-relevant cables): If I connect the same disk to the on-board SATA port then it works perfectly, so I'm sure the problem doesn't lie in the disk itself or in the SATA or power cables. Am I doing something wrong or is this actually not possible? Is there something that needs to be configured in the BIOS settings?
Make sure your specific M.2 --> SATA adapter board's M.2 pin 69 goes to Ground. This will tell Braswell to configure that key-B socket to be in SATA mode (as opposed to PCIe mode.) BTW, that M.2 slot is for M.2 SATA SSD which is 3V IO. You have to make sure your external 2.5" SATA SSD can supports this low voltage operation. Most of the regular SATA SSD drives are 5V type.
I've read that pin 69 (CONFIG_1) must be grounded, but I can't tell whether the adapter grounds it or not. Any tip on how to ensure it's grounded? As for the voltage required by the SSD, shouldn't the power cable supply the required 5V? The adapter I'm trying to use provides only the SATA port (so I guess it only uses pins 41,43,47,49 of the M.2 port, and probably pin 69). To provide power to the SSD I'm using the SATA power connector on the Udoo itselt (CN30), which should provide the 5V required (see the photo I posted before). Am I missing something? Thank you!
No, it's not what about the supply voltage but the signal voltage. M.2 spec is different than the regular sized (2.5" or 3.5") SATA interface. (3V vs. 5V) I'd suggest you ask the vendor on my post #2 questions.
After some testing I did, it seems the problem is with pin 69 not being grounded. I've put a little piece of electrical tape over pin 69 on the adapter and I placed a tiny piece of aluminium foil between the adapter and the M.2 port, short-circuiting pin 69 and 71, which should be grounded (and probably other pins too, but judging by the Udoo manual the surrounding pins don't do anything). The SDD started working! Now, has anyone got a better idea of how to ground pin 69? Otherwise I'm grabbing a power drill and a soldering iron and I'm going medieval on the adapter... About the signal voltage: I can't seem to find any reference to the 3V or 5V, all the references I found (without access to the SATA specifications) point to differentials of less than 1V, but I can't find anything definitive.
Okay, found the info on SATA signal IO (differential pair.) For each signal lead, typical signal swing is in between Ground and 400mV. <-- this is consistent with the recent LVDS This should close my previous concern on that front. I.e., non-issue.
