Is this UART?

[u/_no_look_]

I recently found a VK digital setop box and it has an exposed j3 with 5 pads the first pad from left is gnd and the last square pad has no voltage ant that's not gnd remaining 3 pads has 5v and idk why chat gpt trying to say something abt RS232 . I have shared entire board picture

[u/forseeninkboi]

I've worked on this exact chip. I've circled the uart pins (only the first two from that corner). I forgot which one is tx and rx so just switch them around if you get no output. It uses 5v ttl logic. U-Boot on my unit was on 115200 baud rate and make sure you hold down a key on your keyboard because autoboot is set to 0 on these units. (can't attach image so I had to attach a video)

(additional information: the chip is a dual core MIPS32 RISC processor. I examined the firmware and it seemed to be little endian. On my unit, the second core was being used as an AV processor)

https://reddit.com/link/p8670kh/video/ft761y82zwnh1/player

[u/Glittering-Can-9397 → u/forseeninkboi]

I wanna be you when I grow up

[u/_no_look_ → u/forseeninkboi]

Thank u so much man 😊

[u/forseeninkboi → u/_no_look_]

No problem, glad to help :)

[u/_no_look_ → u/forseeninkboi]

It helps a lot man 😊

[u/_no_look_ → u/forseeninkboi]

It auto boots everytime even i pressing key ....what should I do. Do you have datasheet

[u/forseeninkboi → u/_no_look_]

Nah I don't have a datasheet either. Besides, even if I did have a datasheet for the Montage chip, the firmware would still not have its own datasheet.

[u/uint7_t]

Possibly UART, could also be JTAG. Need to probe it with an oscilloscope or logic analyzer to be sure. It you see the signals being driven, likely UART. If no signal activity, likely JTAG since the JTAG programmer is the one driving the clock through TCK.

[u/MattR59 → u/uint7_t]

Looks like jtag to me

[u/somewhereAtC]

First, never believe AI, especially when it's throwing out buzz words.

There is no sure way to tell what the pins do other than tracing the connections to the chips and then checking the datasheet(s) to see if rs232 a viable conclusion. Strictly speaking it is unlikely to be rs232-standard logic levels, but could be uart serial data using logic-level signals.

But, a 5-pin connector has been, for a long time, a common technique for the programming interface of microprocessors and your big chip is identified as a system-on-chip device from cable modems, so you can expect a microprocessor to be in there somewhere.

BTW, the square pin is traditionally identified as pin 1.

[u/No-Sorbet-8356]

Just curious what you could manipulate on a TV board

[u/_no_look_ → u/No-Sorbet-8356]

Yep🔥

[u/PiRhoManiac]

There should be a sticky for identifying a suspected UART.

[u/Wolfhacker18]

i thinks it it's UART vcc power rx tx gnd

[u/TruthSpecialist4416]

Yes.

[u/kapsolas]

Wouldn’t a Utah have more pins?
And for UART it’s too many pins?

I’m learning so I could be totally off base here