hi, i wanted to ask something about the RK3588 module. would it be possible to buy the one with a smaller amount of RAM, and when chips are cheaper, buy my own chips and solder them on to make a custom 32GB one? while i’m pretty sure it’s physically possible as long as i get chips with the same size, contacts, etc, i’m wondering what i’d need to do to get the chips ready. i’m assuming i’d need to flash firmware of some sort on the ram chip so it can properly communicate with the CPU and other bits which i can absolutely do, but i’m wondering if that’s all i’d need to do (and if so where said firmware would be acquired)? or if there’s other things i’d need to change?
i ask since i’m planning to save for the RK3588 to grab it later this summer and with the lack of availability of the 32 GB model now, i want to see if i could grab the 16GB one and upgrade later (since i don’t care about the flash memory much at all due to using an SSD in my Pocket Reform) when chips are cheaper/available and how much effort such an upgrade would take. if it’s as simple as grabbing some off digikey or similar, then reflashing and soldering then that’s easy.
if anyone can give some input on the feasability of doing this that’d be awesome.
The RK3588 modules use FBGA LPDDR4 memory chips, which are already in place from the fab, so not added by us. In theory they could be replaced but that would probably not be worth the amount of work it would take to do such a replacement unless you were doing it for the express purpose to learn the process. After seeing your post here I tried to look at where one would even get a hold of the raw chips, Mouser has a listing for them but doesn’t have any in stock. Have you done surface mount soldering with such a fine ball grid before?
part of it would be learning, part of it would be because of wanting the upgraded model.
and no i haven’t done it before, actually any surface mount soldering period, but it seems easy enough from the videos i’ve watched. that said i know full well things might go wrong, to keep murphy’s law in mind, etc. so i’m willing and happy to take my chances and learn.
I have been doing some surface mount replacements for much smaller chips that don’t need balling and it is very much not as easy as it looks in the youtube videos. I haven’t yet attempted reballing yet either, though I would like to take a shot at it in the near future.
I would highly recommend not trying to do such a replacement on an expensive device such as the rk3588 as your first try at SMD soldering, try doing it with something small and cheap first as you will most likely make many errors in the process. Try with something you already own that is low risk. Also I have no idea how the flashing of the LPDDR4 would go if it was already flashed in someway from the factory and if the replacement chips would be recognized without changing something in the firmware or controller first. So even if you magically had no issues on your first attempt, you would be on your own figuring out if the firmware recognized the upgraded capacity or model of the chips
The videos people put on youtube make it look easy… it isn’t. Definitely don’t attempt your first SMD work on something valuable. I attempted to upgrade the EMMC on an old chromebook I put linux on. It did not go well… but that’s okay it wasn’t worth anything to me or anyone else at that point. This became my learning board though and I learned how to take chips off without lifting pads and put the ones that aren’t bga back on. I steer clear of working on BGA chips.
so what i’m hearing is find some old computers at the transfer station and practice on those, or one of the, idk, half dozen old DDR1-3 ram sticks i have laying around from aforementioned devices before i try on the RK3588?
if you can successfully move a nand chip from one stick of ram to another (try on some super old 1gb ram stick no one is ever gonna use) and get that transfer to work successfully please post about it here! it IS possible but it takes some serious skill.