Unable to access through serial console - Archer C20 V1

Installing and Using OpenWrt
1

I am trying to access the serial console in my router TP Link Archer C20 V1. I think I have set up everything as required, yet I fail to see the console screen running when I start the router. I recently bricked (or so I think) while trying to install OpenWRT. Could someone please guide me on how to do this the right way? I want to update the wiki page (https://openwrt.org/toh/tp-link/tp-link_archer_c20_v1) with more images and steps after successful installation.

Images of the board and connection: https://imgur.com/a/Wj73JQs

2

Aside from the solder joints eventually not making a good connection to the pads, are the resistors R137, R600, R54 and R601 (bottom side, just next to the serial port) populated or did TP-Link effectively cut the traces there?

3

I could do the soldering again but I think the resistors are empty. Here is a closer look.

IMG-20191003-WA0005
IMG-20191003-WA0005.jpg1280×1086 149 KB

4

While I don't have much faith in the solder joints, R600 and R601 are definately missing, but appear to be needed.

Disclaimer: I don't own that particular device, so I'm merely trying to interpret the provided images, which aren't quite clear enough to provide definitive advice.

5

Any other way to recover? My Ethernet still detects the network when connected to the router LAN. Does that mean the router still works? No LEDs are on our blinking.

6

Use TFTP mode
http://downloads.openwrt.org/releases/18.06.4/targets/ramips/mt7620/openwrt-18.06.4-ramips-mt7620-tplink_c20-v1-squashfs-factory.bin

Download Factory image :point_up: then rename it to (ArcherC20V1_tp_recovery.bin) or (tp_recovery.bin) then upload the image to router via TFTP Server

2 Likes
7

Great. Same steps? Should I change my Ethernet IP to 192.168.0.66 (openwrt method) or 192.168.1.2 (TP link method)? Also no LEDs are lighting up. Should I try to press and hold reset button while trying to power up the router?

8

https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=161a3be5adb21135eb75da81247fa5e04b6ea676

9

  1. Download the http://downloads.openwrt.org/releases/18.06.4/targets/ramips/mt7620/openwrt-18.06.4-ramips-mt7620-tplink_c20-v1-squashfs-factory.bin as shown in the table above.

  2. Configure a computer with static IP 192.168.0.66/24 and a TFTP server

  3. Rename the downloaded firmware file to tp_recovery.bin or ArcherC20V1_tp_recovery.bin and place it in the tftp server's root directory.

  4. Connect the computer to one of the router's Ethernet ports while the router is off. Press and keep pressed the router's reset button and power it up. After about 7-10 seconds release the reset button. The power LED will flicker rapidly for ~3 seconds, indicating download of the firmware file.

  5. The router will write the firmware to flash during ~40 more seconds of occasional power LED blinks, and then will reboot by itself, ready for use

1 Like
10

Or you can follow this metod that posted by slh :wink:

Using tftp mode without UART connection but require some
manipulations with target image

  • Download and unpack TP-Link Archer C20 v1 firmware from original web
    site

  • Split uboot.bin from original firmware by this command (example):

    dd if=Archer_C20v1_0.9.1_4.0_up_boot(160427)_2016-04-27_13.53.59.bin of=uboot.bin bs=512 count=256 skip=1

  • Create ArcherC20V1_tp_recovery.bin using this command:

    cat uboot.bin lede-ramips-mt7620-ArcherC20-squashfs-factory.bin > ArcherC20V1_tp_recovery.bin

  • Place ArcherC20V1_tp_recovery.bin in tftp server directory.

  • Configure PC with static IP 192.168.0.66/24 and tftp server.

  • Connect PC with one of LAN ports, press the reset button, power up
    the router and keep button pressed for around 6-7 seconds, until
    device starts downloading the file.

  • Router will download file from server, write it to flash and reboot

1 Like
11

Thanks for the steps but none of the LEDs are lighting up when I switch on my router

12

Are you able to use lan port or not?!

13

Yes. LAN port seems to get detected when I connect even though no LEDs are on.

14
15

it doesn't matter if your router is able to download the factory image via tftp

16

Excellent. Let me try that and update.

17

You should see something like this :point_down:

progress

18

I use Ubuntu. I'll follow atftp method. Shouldn't make a difference I guess

19

I don't know this metods are for Windows 10

20

Don't forget to rename the recovery image to ArcherC20V1_tp_recovery