Projects/VizioTVServicePort
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[edit] Vizio Television RJ-12 / RJ-11 Service Port & command line access
[edit] Introduction
The lab was generously given a Vizio VX37L television that had failed. During the process of trying to determine which board the failure was in, the question of the 6 conductor RJ-12 connector came up.
A forum post says that a Vizio technician had a user connect a telephone line to this port to do a remote firmware upgrade by calling the customer after a phone line had been connected. The television main board does not seem to have the hardware to support this, as there is no line coupling transformer or modem IC. So further inspection was in order. Do not hook a telephone line to the port unless Vizio tech support says to do so.
A part of me was hoping to find the ability to control the television via RS-232 commands, for easier integration into the 757 Labs AMX control system. This does not appear to be a likely scenario, and we will have to reply on IR transmitter.
After some checking with an o-scope on the pins, it's apparent that data is transmitted on the pins. After further inspection and testing, I figured out that it's possible to get access to the television's processor command line interface.
From this point I was able to see that the main board for the television was crashing upon start up. The unexpected shutdown of the TV was likely due to a problem on the main board. I did not troubleshoot the actual board, but replaced it.
[edit] The connector
On the back of the Vizio television is a RJ-12 connector. It has 6 pins.
- Pin 1 : Unknown
- Pin 2 : TX (black on my cable)
- Pin 3 : Unknown
- Pin 4 : Ground (Red on my cable)
- Pin 5 : RX (yellow on my cable)
- Pin 6 : Unknown
Given the layout of the pins, you can use a 4 conductor telephone cable to build your interface cable.
It could be the case that the RX and TX may need to be swapped. If you are having issue, this is the first place to look.
[edit] The serial setup
THE PORT IS NOT COMPATIBLE WITH STANDARD RS-232!!!!
It appears to use a 3.3 volt signaling. This is becoming more common in modern electronics. The easiest solution is to use a USB to serial adaptor that is setup for 3.3 volts. There are available from internet websites for use with some smaller Arudino kits. The cable I used came from lab member Mike O, and is a Nokia CA-42 serial cable. These cables are available very cheap from eBay and other sites. It has 3 wires in the cable that are as follows:
- Nokia CA-42 cable
- Green = Ground
- Yellow = TX
- White = RX
The baud rate for the television is 115200 bps, 8 data bits, 1 stop bit and no parity. No need for hardware handshaking.
[edit] Once you build your cable and cable up
Once you've connected the television to your carefully crafted 3.3 volt serial cable and connected to your computer, open a terminal program. On Linux you can use minicom or screen. On Windows XP hyperterminal will work. No idea what Mac has available and set it to use the USB serial adapter and set the proper baud rates.
Turn on the TV. You should see the initial boot up of the television.
[edit] TV bootup output
YSPLL now is 324000000 Hz DMPLL is set as 378.0 MHz The memory is DDR-I 2 Chips DQS 0 - (0 ~ 41) set 20[0x14 - 0x2b](0xe9) DRAM is set as 32 bits Set PSPLL to 148500000 Hz... Set VPLL to 81000000 Hz... Set ADCPLL to 81000000 Hz... Set B2RPLL to 148352000 Hz... Calibrate APLL1 to 270950400 Hz... Calibrate APLL2 to 294912000 Hz... MT5371 Boot Loader v0.2 Booting... Decompression image to 0x02b00000...OK! Image size: 5113232 bytes (0x02b00000 - 0x02fe058f) Starting image... Before IRRX State: 0 After IRRX State: 0 DRAM_CLK: 189000000 bApiTunerInitInUSA ch1 calibration start input offset calibration is 2 Transition point is 17 ch1 calibration is done input offset calibration is 0 Transition point is 17 DTV>
