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1st February 2018, 08:16 | #1 | Link |
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Serial settings for the newer LG drives
Many (all?) of the newer LG drives - those based on the Mediatek ARM SoC, not the Renesas drives - appear to have 3.3v (CMOS logic) serial headers on the back, next to the SATA/power connectors. Based on a quick look with an oscilloscope, it seems that the ramp down/up for one bit is somewhere between 113 ~ 120 kilohertz, so I'd guess that the serial line speed is 115200. However, when I connect a USB<->Serial device I get garbage in minicom. Does anyone on this forum know the correct settings?
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1st February 2018, 09:56 | #2 | Link |
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You can first try to play with the several standards settings for an RS232 port COMs :
Parity bit : None, Odd, even Stop Bits : 1,2 This will make 6 settings to test. I doubt you'll have to test for 7 bits data... But, do you know what you're supposed to receive and/or send ? It's not because it's a serial link that you're supposed to receive text. There is often serial link on devices for testing/maintenance purpose, which send (or receive) pure binary data/information. Last edited by jpsdr; 1st February 2018 at 09:59. |
3rd February 2018, 17:30 | #3 | Link |
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These are correct settings. MTK firmware does not log strings, instead it uses a custom binary log format with message IDs and arguments encoded as binary. Useless without formware source code. What exactly you wanted to see there?
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4th February 2018, 06:20 | #4 | Link |
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I was hoping that there was some way to upgrade, downgrade, or patch areas of the firmware via the serial console. Maybe implement some sort of rudimentary GDB backend, if possible. Would you be willing to share what you know of the binary protocol (if anything)? Can you confirm the remainder of settings for the serial interface, including data bits, stop bits, parity, and flow control?
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5th February 2018, 21:24 | #6 | Link |
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Indeed, the 8n1 serial configuration seems to be in widespread use. I don't remember ever using a serial device with settings other than those. However, this is a highly specialized device which is probably hostile to unauthorized users and it wouldn't surprise me if some parameters were nonstandard. The problem is that since the protocol is binary I have no way of telling whether the data I see is garbage as a result of say 2 stop bits instead of the usual 1 stop bit.
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5th February 2018, 22:00 | #7 | Link | |||
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