juuso wrote:Due increasing count of bricks (few days ago - Denny`s ES series, today - mine D series once again) it is needed to have some "safe" and relative easy way to send "toggle" to the micom to switch boot flags. Last brick - due internal errors while flashing rootfs (squashfs errors of flashed partition, despite the bml.restore & sync procedure went without any error.)
Maybe it is possible to locate micom config eeprom and make short circuit during TV boot or maybe send there some voltage to some specific pin? Another thoughts?
1) Micom EEPROM (should be easy to locate - small one, usually close to the Weltrend chip) reset/shorting may help, or not - you have only 50/50 chance default partition after reset will be the one you want to select (i.e the one still in working order). There is a good chance after micom reset you will lose serial console settings (not a biggest problem - console will be still available on 74HC4052D chip pins), and watchdog setting too.
2) Forcing partition select by SoC GPIO <-> Weltrend GPIO pins/trace shorting: in theory it should work (at least in Valencia/Genoa/Echo-P based TVs), but in reality the proper pin/track will be really hard to find - there are 30+ possible candidates on the Welltrend side, and I don't see any easy method to round them down by using the scope/voltometer etc.
3) Tap into serial/rs232 connection between main SoC and Micom (e.g with Arduino, Raspberry Pi etc. - beware of the rs232 voltage level, should be 3.3V or maybe even 2.5V in recent models) and try to issue raw partition toggle command directly to micom. With the scope those 2 serial connection traces should be relatively easy to locate, even on bricked TV. But after main SoC power-up, it will be a "live" connection, I'm not sure such solution may be possible without frying something on the SoC side.. And before SoC power-up (in standby mode), micom will probably refuse to accept any commands issued on this connection.
4) Samsung still includes "main reset switch" on all (?) their recent mainboards (switch is generally missing - not soldered, but the circuity it is connected to actually exists). I wonder if shorting this switch pads may be actually good for something - e.g., it may trigger the Micom configuration reset or something.. I guess it will have the same risks involved as 1), plus some additional unknown ones
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Tried to make short circuit on every (
) 8-pin chip on the mainboard
Probably not a best possible idea - usually some of those "8-pin chips" are in fact transistors belonging to various voltage regulator circuits!
