Help recording data from 1.8V serial interface
Jakob Cornell
Hi folks,
I have a Kindle-shaped brick that's been sitting around for a while and it's time to either fix it or get rid of it. The model I have is the subject of this teardown which gives details about some pads on the main board where the system is said to produce boot loader and OS logs.
Have you dumped serial data before with a 1.8V logic level? Would a logic analyzer be able to do this in a convenient way? In terms of hooking it up to my PC I'm not sure how close this interface is to RS-232; maybe just needs a level conversion? How would you go about this?
Thanks,
Jakob
Anthony Canino
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Jakob Cornell
I was able to use Anthony's USB/serial adapter to dump the logs and it appears the OS is booting fine!
Since that went so well why not increase the difficulty? Here's the logic board from a printer that's acting very strangely. Try as I might I haven't been able to get diagnostic information through any documented means (Samsung management software via USB, paper printouts, web portal via built-in AP).
In addition to the top and bottom rows of mysterious test points there are four interesting looking pads in the bottom right. There's 3.3V across the outer pair and the other two seem to lead back to what I presume to be the (undocumented) MCU or SoC in the middle.
Maybe there's a UART behind this, or maybe it's I2C? I could assume UART and guess at a baud rate and which pad is TX, but I would love a more systematic approach. Any ideas?
Jakob