Serial connection DAP-X1860 AX1800

Attempting to access the DAP-x1860 serial console on stock firmware fails for me.
Got it opened up, soldered UART header. Hooked up UART with either a USB tty adapter or Raspi 4 GPIO RX/TX/GND but on either I cannot get any output.

I access the device via screen /dev/ttyUSB0 115200 respective screen /dev/serial0 115200.
I would expect to see some bootlog (as others already provided such in the development thread).
(During normal boot as well as when entering recovery)

Was further preparation of the board necessary in order to gain access?
Any ideas how I could debug this?

You probably need to provide an image with labels to show what you've hooked up to GND / TXD / RXD here.. and ideally a link back to the development thread so that other people can more quickly get up to speed with exactly what device you're talking about.

Are you sure 115200 is the right baud rate? (and I assume you have it configured for 8 N 1 also?)

Header is probably far right on internal photos pg 6 ?
Can't make out any details though, I'm on a cell phone :frowning:

You may be able to find more information here:

@JayBraker - Please don't bifurcate this discussion though (it can cause all sorts of confusion) -- It is best to keep your discussion here, or we can actually merge your thread into that one if you'd like (let us know).

Right, I'm pretty sure screen is configured for 8N1 as it worked on different devices expecting this config but I will check again with minicom which allows me to specify the conf

I uploaded 2 pictures showing the used header + board labels:
Black wire to the very left is tx on my serial device, grey is gnd, red is rx
Already swapped black and red, no success

psherman provided the correct link - I'm not sure about throwing this into the Support Thread, the people there probably had success with serial connection but its not really of majro concern if they got it working..

Yeah, thats it
The labels seem somewhat off in the fcc docs but its just really blurry

Pics of my board in latest reply


adding part of pic here ...

At least this thread was not closed after 3 days of inactivity yet :slightly_smiling_face:

Many USB TTL adapters have the RX LED connected directly to the data line (pulling it to a high level), which prevents some devices from booting. This happens for me with DAP-X1860 as well, the status LED will just stay faint orange if the adapter is connected during plug-in. In that case, you can either add a series resistor, de-solder the RX LED, try a different TTL adapter, or just connect the RX line a couple seconds after plug-in, when the status LED has turned bright red. This may result in missing the uboot countdown, but you can keep reset button pressed during power-on, and will end up in the http recovery. Connecting the console and pressing Ctrl+C will get you back to uboot shell.

From a running device, you should be able to connect the console at any time, but there is not much output to see after is has fully booted. Usually, the first thing to connect is GND and TX -> RX (router to TTL adapter) and see if something shows up, only then connect the RX <- TX line as well.

If it still does not work, check the soldering on the GND pin with a multimeter, this is usually a lot more difficult as the GND plane absorbs a lot of heat, it may look like correctly soldered, but have no contact.