Hello.
I'm sorry if I'm posting in wrong forum.
I bricked my router and I need a UART to unbrick it. I'm new to UART's and stuff like that and I don't know what UART to choose. One guy told me mostly I need 3.3V. That UART will be okay https://www.ebay.com/itm/Metal-case-USB2-0-to-TTL-UART-5PIN-Module-Serial-Converter-CP2102-STC-PRGMR/222503843286?epid=1250535213 ?
Also I find in my local shop this USB To TTL Adapter FTDI FT232RL, jumper 3.3v-5v, USB, it will be okay ?
I just read that in case I use a 5V UART on a device where 3.3V need to be used it could blow the chip
On router back it says 24V-2.5A
If I need to provide some more info just say it and I will do it

 

Before you go buy a USB/serial board, I would recommend that you familiarize yourself with the method of unbricking for your particular router.

Yes, using 3.3V USB/serial board to communicate with another 3.3V serial port is an important consideration.

Some routers can be unbricked using a serial port - see tutorial here. Some routers can be unbricked using the LAN connector - see tutorial video here.

"On router back it says 24V-2.5A" That sounds like the power supply input that the router wants (the wall wart or whatever is supply that to the device). That information is good to know but is not going to be helpful with the unbricking.

So,
What router do you have - actual brand and part number?
What OS are you using?
What instructions are you going to follow to accomplish the unbricking?

If you can provide those answers, it would help.

 

What router do you have - actual brand and part number?

UBNT EdgeRouter X

What OS are you using?

Windows I will use PuTTy

What instructions are you going to follow to accomplish the unbricking?

https://openwrt.org/toh/ubiquiti/ubiquiti_edgerouter_x_er-x_ka#opening_the_case
http://sector5d.org/openwrt-on-the-ubiquiti-edgerouter-x.html
In think there is spaming that's a bootloader error like in second video and I will just replace file with a correct bootloader

First at all I want just to buy a UART that will work with my router and see what is happening there

 

Sounds like you have a plan - good deal.

I have used this one with success in a variety of situations. Recommended because 1) it really does switch line to TX at 3.3V - you just change the position of the on-board switch, (some only switch Vcc), 2) genuine FTDI (as far as I can tell) and I have never had any driver issues (not as easy to say with some other boards). It is not the cheapest, but it is a good one in my opinion.

Edited for clarity and to add.
With the USB/serial board I linked to, you do not need to be cutting and soldering traces - just use the switch.

If you don't like the paper clips and you expect to be bricking the router again in the future, you can solder header pins on the router:

You will also need jumpers.

Edited again. You can easily test the USB/serial board by connecting RX to TX on the USB/Serial board. Then, in Putty you will see what you type - just an easy test before you go into the router.

 

Sounds like you have a plan - good deal.

I have used this one with success in a variety of situations. Recommended because 1) it really does switch line to TX at 3.3V - you just change the position of the on-board switch, (some only switch Vcc), 2) genuine FTDI (as far as I can tell) and I have never had any driver issues (not as easy to say with some other boards). It is not the cheapest, but it is a good one in my opinion.

Edited for clarity and to add.
With the USB/serial board I linked to, you do not need to be cutting and soldering traces - just use the switch.

If you don't like the paper clips and you expect to be bricking the router again in the future, you can solder header pins on the router:

You will also need jumpers.

Edited again. You can easily test the USB/serial board by connecting RX to TX on the USB/Serial board. Then, in Putty you will see what you type - just an easy test before you go into the router.

It's only US Shipping. I'm not from US.
I don't want to buy online because I will need to wait ~10-20 days for it.

This is only one that I found in our local shop USB To Serial 232 Adapter FT232RL (5V-3.3V jumper)

How do you think this will be okay ?

 

It's only US Shipping. I'm not from US.
I don't want to buy online because I will need to wait ~10-20 days for it.

This is only one that I found in our local shop USB To Serial 232 Adapter FT232RL (5V-3.3V jumper)

How do you think this will be okay ?

Maybe. So, you want to plug it in to your PC and look (with a meter) at the lines when the switch is 3.3v to make sure that TX really is working at 3.3V. Of course, you want to make sure that the router is 3.3V as well. In other words, you just want to make sure that you are matching the voltages on TX/RX on both sides. Not being paranoid, but they are sometimes misleading (see video below).

 

Maybe. So, you want to plug it in to your PC and look (with a meter) at the lines when the switch is 3.3v to make sure that TX really is working at 3.3V. Of course, you want to make sure that the router is 3.3V as well. In other words, you just want to make sure that you are matching the voltages on TX/RX on both sides. Not being paranoid, but they are sometimes misleading (see video below).

I can just get any voltage meter from ebay or it's better get this like in video, but I can't find like this on ebay

 

I can just get any voltage meter from ebay or it's better get this like in video, but I can't find like this on ebay

Pretty much any volt meter.

 

Pretty much any volt meter.

When I connect from Putty it's just a blank screen and nothing happen ?
What can be the problem ? I tried to use speed 9600 and 115200, where I can find what speed I need to use ?
It can be possible that I can't see nothing in putty because UART is lower voltage then 3.3V ?
Any more reasons why I see blank screen in putty ? How much time usually do I need to establish connection ?

 

When I connect from Putty it's just a blank screen and nothing happen ?
What can be the problem ? I tried to use speed 9600 and 115200, where I can find what speed I need to use ?
It can be possible that I can't see nothing in putty because UART is lower voltage then 3.3V ?
Any more reasons why I see blank screen in putty ? How much time usually do I need to establish connection ?

Did you look at the voltage on the pins of the USB/Serial chip and your router connections? If so, what were they in each case?

Please explains the details of your connection:

What did you connect to what - which lines went where?

What are the voltages between GND and each of the other pins on the USB/serial chip with the hat switch on 3.3 and also when on 5V?

When you plug the USB/serial board into the PC, can you see which COM port it has occupied? If not, then the driver on the PC is not loading. If so, then make sure you have that COM port selected in Putty.

Sorry for so many questions, but I can't see what is happening on your end.

 

Please explains the details of your connection:

All like here
https://openwrt.org/toh/ubiquiti/ubiquiti_edgerouter_x_er-x_ka#opening_the_case

What are the voltages between GND and each of the other pins on the USB/serial chip with the hat switch on 3.3 and also when on 5V?

I gave it to a friend of mine, and he tested with volt meter. He said is okay.

When you plug the USB/serial board into the PC, can you see which COM port it has occupied? If not, then the driver on the PC is not loading. If so, then make sure you have that COM port selected in Putty.

Yes, I can see. But his name(driver name) is USB Serial Port, but not FT232RL. I tried to change COM port too, nothing changed.
Jumper is set on 3.3V

 

All like here
https://openwrt.org/toh/ubiquiti/ubiquiti_edgerouter_x_er-x_ka#opening_the_case


I gave it to a friend of mine, and he tested with volt meter. He said is okay.



Yes, I can see. But his name(driver name) is USB Serial Port, but not FT232RL. I tried to change COM port too, nothing changed.
Jumper is set on 3.3V

Well, based on what information you have provided, I am sorry, but I don't know what the problem could be. Maybe the router is gone.

 

Well, based on what information you have provided, I am sorry, but I don't know what the problem could be. Maybe the router is gone.

So the speed set in putty does not matter ?
There is a problem with UART drivers/UART or router ?
voltage is lower than 3.3V also can cause this error, right ?

 

So the speed set in putty does not matter ?
There is a problem with UART drivers/UART or router ?
voltage is lower than 3.3V also can cause this error, right ?

An easy way to test whether your USB/serial board works is to plug the board into your PC with nothing else connected - just the USB/serial board. Then, connect the TXD line to the RXD line. Open Putty and what you type should also appear in the Putty window. If the USB/serial board works and is recognized by your PC, that will work. Doing this, essentially tells you that the drivers and the USB/Serial board are good and installed correctly and that Putty is configured correctly.

Once you get to that point, you can start investigating further.




edited to add pic

 

View attachment 156417

An easy way to test whether your USB/serial board works is to plug the board into your PC with nothing else connected - just the USB/serial board. Then, connect the TXD line to the RXD line. Open Putty and what you type should also appear in the Putty window. If the USB/serial board works and is recognized by your PC, that will work. Doing this, essentially tells you that the drivers and the USB/Serial board are good and installed correctly and that Putty is configured correctly.

Once you get to that point, you can start investigating further.




edited to add pic

Thank you.

Do you know how I can change this https://www.ebay.com/itm/Metal-case...CP2102-STC-PRGMR/222503843286?epid=1250535213 to run at 3.3V ? I don't see it to have any button,switch or jumper.

I have a voltmeter now photo
Sorry for advertisement, this is only photo I found with my model.
How to check voltage ?
Where should be arrow of voltmeter set ?
I plug black cable in COM Input and red in VΩmA and after that use one connect with ground and other to connect with 3V3. What color should go to 3v3 and what to GND ?

 

Thank you.

Do you know how I can change this https://www.ebay.com/itm/Metal-case...CP2102-STC-PRGMR/222503843286?epid=1250535213 to run at 3.3V ? I don't see it to have any button,switch or jumper.

I have a voltmeter now photo
Sorry for advertisement, this is only photo I found with my model.
How to check voltage ?
Where should be arrow of voltmeter set ?
I plug black cable in COM Input and red in VΩmA and after that use one connect with ground and other to connect with 3V3. What color should go to 3v3 and what to GND ?

I do not see a way to switch that one to 3.3V.

Using your first pic as an example:

Using a meter - "black cable in COM Input and red in VΩmA and after that use one connect with ground and other to connect " to.... TXD and RXD and DTR and 3.3V and 5V. If it is a 3.3V device, then no pins except for 5V will be above 3.3V. If pins are above 3.3V then you can damage the router if it wants only 3.3V signals.

Remember the video I posted in #6? The "danger" is that TX is at 5V and if it is transmitting to a device on the other end (your router) and that device can not take a voltage above 3.3V, then there can be damage. That is why you check the voltage on all of the pins.

Colors of the leads don't really matter (it's nice for GND-black and 5V or 3.3V-red).

 

Using a meter

The arrow should be set where I draw a red dot or in other place ?

 

The arrow should be set where I draw a red dot or in other place ?

I would suggest that you read the manual for the meter - now that you have the tool it is a big advantage to learn how to use properly - right?. That being said, it looks to me like the "arrow" should be set to the 9V notch.

 

I would suggest that you read the manual for the meter - now that you have the tool it is a big advantage to learn how to use properly - right?. That being said, it looks to me like the "arrow" should be set to the 9V notch.

Where is 9V it's Battery test.
from 200m to 500 it's DC voltage, 500 to 200 it's AC Voltage.
I can list other options but I think i need one of this to test UART

 

You want to measure a DC voltage. That voltage should be no more than 5V but you want to set the meter to a scale higher than the highest voltage that you expect. If you set it much higher than the voltage that you are measuring you will lose some resolution, but you can certainly start higher and move lower. If I am understand you, then there is a 20VDC scale and that is probably fine. Again, the instruction manual for the meter is your friend.