Asus RT-AC5300 serial pinout

[sx00199]

hey there,

Does someone know the serial pin layout?

Looking at https://cdn2-techbang.pixcdn.tw/sys...ef8c50426517b29530d4e935a42411.jpg?1450262506
I believe the serial is at the top right...
Can someone tell me the tx,rx and gnd pin (from left to right?)

Thx in advance

 

[Pierino]

Usually asus labels them. You can figure out ground with a volt meter. Vcc is usually one of the end pins with a square look to the pin out. It will look different than the other three. Vcc will measure around 3v.

Take your negative lead and touch it to a ground spot on the board, like an antenna mount or a USB. Then take the other lead and touch the pins one at a time. When you have continuity, you'll know that's ground.
As long as you connect your ground serial wire to that, you should be ok.
Then hook your other 2 wires to the pins that aren't the vcc.
If you don't get any output from your serial console, switch the 2 wires around.

The picture is blurry but I think vcc is the right most one.

 

[sx00199]

Thanks for responding. Unfortually asus "forgot" to label them

I'm picking up a multimeter tomorrow, so I'll try your directions.
Thanks again!

 

[RMerlin]

I can't check on mine because it's no longer disassembled (I opened it, drilled a hole in the venting slots to run some three terminal wires through, connected a serial adapter and closed the case), but generally what was posted before should be enough to get you up and running: pin 1 (the one with a square marker) is VCC, which must NOT be connected. 2 and 3 are tx and or rx (you can test both ways to determine the correct pin order), and pin 4 is Gnd.

 

[sx00199]

Thanks all for your help.

I hooked up my serial cable, it's an USB2TTL one, 4 pins, 3.3V.

Once hooked up to the correct pins, all my router does is light up the LAN, POWER and blink the WAN1 led. No serial console or whatsoever.
Once I unhook the serial connector, all my router does is light up WAN for 0.5 SEC, then constant POWER led.

No IP, No Recoverymode (30/30/30) no response to WPS button (clear nvram).

Am I toast or can I try something else?

 

[themiron]

Once hooked up to the correct pins, all my router does is light up the LAN, POWER and blink the WAN1 led. No serial console or whatsoever.

WAN1 blinks because you mixed up RX & TX pins

 

[Marin]

hey there,

Does someone know the serial pin layout?

Looking at https://cdn2-techbang.pixcdn.tw/sys...ef8c50426517b29530d4e935a42411.jpg?1450262506
I believe the serial is at the top right...
Can someone tell me the tx,rx and gnd pin (from left to right?)

Thx in advance

I am getting ready to connect a serial too and I couldn't see the picture. Would you be able to send me a picture of it if you still have it? Would you also be able to let me know what your VCC, RXD, TXD and GRD ports were? Thank you so much!!

 

[Marin]

I can't check on mine because it's no longer disassembled (I opened it, drilled a hole in the venting slots to run some three terminal wires through, connected a serial adapter and closed the case), but generally what was posted before should be enough to get you up and running: pin 1 (the one with a square marker) is VCC, which must NOT be connected. 2 and 3 are tx and or rx (you can test both ways to determine the correct pin order), and pin 4 is Gnd.

So I connected serially to my ASUS RT-AC5300 and through Putty and I cannot get to the cfe > commands by pressing Ctrl +C. It takes me straight to the DD-WRT login (had Kong’s 3/25/18 firmware installed prior to this bricking) and it keeps telling me that my login is incorrect despite entering my user name and password. Does this mean that my CFE is corrupt? Is there a way to bypass this DD-WRT login info in Putty? Do you think it is time for JTAG recovery? I am new at this but I hate not making any efforts at reviving this if there are any.

 

[Pierino]

Start pressing control and c as soon as you power up the router.
This should interrupt the boot process. Then type nvram erase. That should reset it.
There is no jtag support for this.

 

[Marin]

Thank you very much! I did do this but maybe I didn’t wait long enough to see anything showing in Putty. I kept pressing Ctrl+C as soon as I turned on the router but didn’t see anything pop up in Putty screen for me to enter any commands (it wouldn’t let me type anything). Does this take some time to show up? How do you know when it is time to do this?

I will try this process again. Also, I read above that if the WAN light is blinking you need to switch RX and TX places-I tried this and the WAN light is solid so this makes sense. Does the power light and all other ones come on eventually?

Also, if I am successful with nvram erase, do I need to go back to flash the original DD-WRT firmware (or the bin file) or would it be possible for me to flash the original Asus stock firmware from TFTP and Putty.

I have one more question. I have an Ethernet cable attached to WAN1 of the router which is also attached to my PC but somehow I turn on the router and try to press Ctrl +C, my LAN icon in my computer states that the “Ethernet cable is unplugged”. I have configured the IP as static so I can use TFTP later. When I unplug the serial cable, the Power LED lights up and then it seems to recognize the “unknown network”. The interesting thing is that if plug the serial cable after I start up my router, only then I begin to see boot info appearing in Putty. Do I have to worry much about the Ethernet cable issue since communication to erasing NVRAM in Putty along with other commands are primarily going through the USB cable? I am assuming that the Ethernet cable will be needed when I flash the new firmware, correct?

Thank you very much!

 

[Pierino]

If you get putty output by hooking up the wires after it boots, that's ok. Strange but ok.
Also, the Ethernet goes into one of the LAN ports then to your pc. Not the wan port.
Yes, you will need an Ethernet cable going from your pc to a LAN port of the router.

 

[Marin]

If you get putty output by hooking up the wires after it boots, that's ok. Strange but ok.
Also, the Ethernet goes into one of the LAN ports then to your pc. Not the wan port.
Yes, you will need an Ethernet cable going from your pc to a LAN port of the router.

Yes, I am sorry-i meant to say LAN1

 

[Pierino]

Where are you located? If you want to pay for two way shipping, I can try for you.
I've fixed a few routers for people on the dd-wrt forum.

 

[Marin]

Des Moines, Iowa. I tried again to stop the reboot but was unable to. The load still takes me to the DD-WRT login section (kongac 3/25/18 firmware version) and despite what I put in, it keeps telling me login is incorrect.

Putty’s output still works when I plug in the serial after i turn the router on but not before.

Pressing Crtl +C does not do anything. The reboot continues no matter what and then everything stops at DDWRT login.

 

[Pierino]

I'm willing to try if you want me to.

 

[Marin]

So I am able to get to the CFE> commands through serial. I need some help in flashing the stock firmware through TFTP and have some questions:

1. After I do “nvram erase”, the DD-WRT wiki indicates, that I flash the stock firmware using this command: “flash -noheader : flash1.trx”. I have TFTP pulled up with the right IP address and folder with stock firmware but nothing downloads. Putty gives an error “TFTP server error.

2. Are there any other commands to flash your stock firmware?

3. Do I need to reboot the router after nvram erase?

3. Does the flashing firmware need to be a .trx file or a .bin one instead? I see many YouTube videos, people change the name of their firmware to match what their router is looking for. Do I need to do this?

4. Attached is a screen shot of what I have entered (according to DD-WRT wiki at ahttps://www.dd-wrt.com/wiki/index.php/Serial_Recovery) and the response I am getting.

5. Also, what type of stock firmware do I need to flash (the most recent Asus one or one of the older ones)?

6. Since this router was flashed with DD-WRT (Kong’s 3/25/18 firmware) when it was bricked, should I use this .bin file to flash instead?

Do you have any suggestions/advice at what I am doing wrong?

Thank you!

 

[Pierino]

flash -noheader : nflash1.trx
Best to recover it with stock fw. Or if you want use the trx build of Kong’s. Are you getting ping responses of ttl=100?
http://www.desipro.de/ddwrt/K3-AC-Arm/Asus-RT-AC5300-firmware.trx

 

[Pierino]

I also prefer to use tftpd32. You could use the cfe mini web server or the asus firmware restoration utility.

Set your pc like this:
192.168.1.9, 255.255.255.0, 192.168.1.1
If you don’t ping responses of ttl=100 after the became erase then you can’t upload the firmware and you will get a timeout error.

 

[Marin]

I am happy to announce that the router is fixed and all the lights are flashing!! After I did a nvram erase, instead of using TFTP, I simply issues a reboot command in Putty, then did a hard 30-30-30 reser once unnoticed that lights were flashing.

This led me to Asus CFE recovery page. I uploaded the the stock firmware, waited until it rebooted and VOILA!!!

Thank you all for your help!!

 

[Pierino]

Don’t do a 30/30/30 on newer routers. Especially not asus routers.