(Yea, in response to prospective elongation. But maybe this is a better place to be more earnest/less guarded that birbsite)
Cleaned relay contacts allowed operation for a few minutes before failing again, confirming the source of the problem. Will replace all of them with new ones.
Made a cutie keepsake with the relatively intact on.
Misc interesting find while analysis bootstrap code 2/?
Samsung engineer: we have DMA at home
DMA at home: huge ass stmia/ldmia
Misc interesting find while analysis bootstrap code 1/?
If the device comes out of reset from power up state, do things normally. However if powered down, get a jump adress from some power-safe, forgo all setup and just jump there
This is compatible with what I remeber of PalmOS behaviour, and explains the JTAG-unavailable-while-screen-off thing
slightly sex
Incidentally, you find this gem in the mcu ds. Not everyday do I get to put CW sex for datasheet screenshot eheh
Quick gear shift: out with the logic analyzer, in with the USB-to-jtag converter. Then get to work on an openocd config file. To that end, you will have previously found out what's on board. (L) is a Samsung s3c2410a20 arm920t, for instance, (F) is a 256mb NAND, and (A) is a 128mb SDRAM. Downloading and quickly perusing the datasheets helps to plan/set goals. Here I want to dump NAND and also get the setup code used by Palm OS to understand how it all work together.
Incidentally you identify a /reset signal, when low the Palm reboots. So you get this pinout, and can go to the more software side of things as you have full jtag with access to the mcu.
So you have 10 wires, one for each pad. You need to identify the 4 jtag signals (jtck, jtms, jtfi, jtdo). You use the micontroller to generate jtck and jtms, only the minimal amount required for the device to talk to you, and you try every combination until you get results on the logic analyzer. (here we see it shift out the TAP idcode on channel 0, so that's a win for 2,5 and 8 as jtck, jtms and jtdi respectively)
Here: photography | grey market HRT | feels
Over there:
@liothique@tech.lgbt : electronics | computational chemistry
Am of the gay.
she/her