Posted: Fri May 22, 2020 1:19 Post subject: Recent R7000 board revision - serial not working.
Wanted to see if anyone has had any problems getting the serial port on the R7000 working. I had one R7000 and bought another specifically for dd-wrt, so I had a working model while I played...
Have a current R7000 dd-wrt setup, so that works, but for the life of me I could not get the serial port to work. Its *possible* I damaged the board, however it definitely detects the serial port being present - just doesn't send anything. The USB dongle could be damaged (I will test/buy more), but I wondered if anyone could verify that there is not now some special trick or unlock for the serial port...
I tried:
* GND, RX, TX
* GND, TX, RX
* (with sudo) screen, putty, plink, minicom (none of which appeared to see a terminal, or effect a change)
* socat (which didn't appear to log anything)
* several USB 3.0 ports on a recent linux laptop
* a USB port on a desktop windows
* Trying to hold down a key as I powered up the router with the serial attached.
I should note the R7000 had a known-bad version of firmware on it to begin with, when I upgraded it, things started to work fine again w. regard to being able to flash DD-WRT and OpenWRT.
I can provide board numbers etc. if anyone can confirm theirs , or has anything they could think of to try...
As I said, next steps for me would probably be to try to use the Serial Port to send a message to a device I can control like a Teensy or Raspberry Pi, but that's a bit more work that I was prepared for just trying an initial flash.
The first link is more or less what I've already followed.
I don't have a Macbook Pro, I have a laptop with USB 3.0 ports (full female A ports, not USB C ports), my cable adapter is different too but essentially the same thing: https://www.amazon.com/gp/product/B01LRVQIFQ/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&psc=1
- there's no reason this should not work and it succeeds at a loop back test (connect RX to TX and observe characters echo when running `screen /dev/ttyUSB0 115200`).
The images in all these guides are incorrect/misleading. I did find some images on the internet which show '1', '2' - GND, '3' - TX, '4' - RX, which seem to correspond better (my board has the pin placement in a completely different location/orientation that most of the online photos, but has the numbers 1 and 2 next to two of the pins). I will open my other router today and compare boards, I strongly suspect they are *different boards*.
Anyways, I get to about the equivalent of step 12 (I said I tried holding down keys, I suppose I could retry mashing ^C however other sources mentioned just triggering the port with any key...) and nothing happens.
I suppose I will retry that last step today, but otherwise not particularly helpful to me, sorry.
I will post back with images/more info when I have it.
Joined: 08 May 2018 Posts: 14244 Location: Texas, USA
Posted: Fri May 22, 2020 15:11 Post subject:
You can verify the +3.3v and GND pins with a multimeter and work from there. DO NOT CONNECT THE +3.3v LEAD. USB adapter TX to router board RX, and adapter RX to TX on the board.
Hold CTRL+C and apply power.
ALSO, if this is an R7000P, it will be different. Somewhere in the forum, I posted a picture in a thread specific to the R7000P with proper labeling of the pins. _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
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Off of the board I already verified with a multimeter yesterday which was the 3.3V lead pin (the first - well actually there are two, but).
I did so again with my other board:
With respect to what I believe is ground the first is 3.3V, the TX is 3.3V as well, the RX is 0.0 V.
My USB dongle, w respect to the GND both RX and TX seem to be idling high (not sure this is correct).
So I'm going to buy some more serial cables (can't hurt to have a couple extra?) and see if I can get this usb to ttl cable working with anything else today...
The boards are definitely slightly different models, constructions.
I'm pretty sure they are both r7000s, even took a picture of the label on the one from yesterday.
Ok, so I verified that this is indeed a new version of the R7000 from 2018. I am not sure that the newer version identification info has been incorporated in FreshTomato or DD-WRT at present. The board_id information is DIFFERENT (see white labels on boards).
EDIT: I forwarded your original images to the developer to inquire if the 12/2018 revision has been properly added to the firmware support. I also contacted the FreshTomato dev team as well.
Also, to verify GND, you use the shield of the USB port or the actual GND from the power supply input jack. Then you verify the rest of the pins. At least that is how *I* do it.
