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I don't actually need to debrick this WNR2000v3, I'm just trying to learn how to connect to an embedded device using a serial connection to see if I can do it.

I believe I have setup the wires so that they correspond to the following diagram (please let me know if I have not)...

Diagram from https://johanbijker.blogspot.com/2012/07/tp-link-mr3420-serial-connection-with.html

I found this in a blog about serial connecting to another router using minicom.

pi@raspberrypi:~$ sudo -i
root@raspberrypi:~# ps -ef | grep ttyAMA0
root       818     1  0 19:34 ttyAMA0  00:00:00 /sbin/getty -L ttyAMA0 115200 vt100
root       920   913  0 19:36 pts/0    00:00:00 grep ttyAMA0
root@raspberrypi:~# kill 818
root@raspberrypi:~# minicom -b 115200 -o -D /dev/ttyAMA0

Then it says to power on the router...

Found additional information about which pin was which on the UART of the router from this page:

WNR2000v3

The serial port is at JP1: 115200 8N1 at 3.3V. Pads are, from left to right with the ethernet ports on right: [Vcc] [Tx] [Rx] [GND]

Wiring Setup

When I used minicom I did receive a bit of output, but eventually it falls apart, and I'm unable (as far as I can tell) to communicate back to the serial terminal:

Welcome to minicom 2.7                                                                

OPTIONS: I18n                                                                         
Compiled on May  7 2017, 05:18:49.                                                    
Port /dev/ttyAMA0, 15:32:21                                                           

Press CTRL-A Z for help on special keys                                               



U-Boot 1.1.4-g98735ae5 (Mar 24 2011 - 15:19:45)                                       

WNR2000v3 (ar7241) U-boot dni17 V1.3                                                  
DRAM:                                                                                 
sri                                                                                   
ar7240_ddr_initial_config(138): virian ddr1 init                                      
#### TAP VALUE 1 = 0x2, 2 = 0x2 [0xadfe85da: 0xd6b9dbf9]                              
32 MB                                                                                 
Top of RAM usable for U-Boot at: 82000000                                             
Reserving 283k for U-Boot at: 81fb8000
Reserving 192k for m
                    Reserving 44 Bytes for Board Info at: 81f87fd4

                                                                  Reserving 36 Bytes for Global Data at:0

                                                                                                        0

                                                                                                        8


                                                                                                        f

                                                                                                        4

                                                                                                        B

                                                                                                        l

                                                                                                        l

                                                                                                        l

                                                                                                        h

                                                                                                        .

Is it possible the resister I'm using is too strong?

resistor

Or do I need to change something in my minicom settings?

Edit

Thanks to Joan's input about minicom, I'm now able to read:

U-Boot 1.1.4-g98735ae5 (Mar 24 2011 - 15:19:45)                           

WNR2000v3 (ar7241) U-boot dni17 V1.3                                      
DRAM:                                                                     
sri                                                                       
ar7240_ddr_initial_config(138): virian ddr1 init                          
#### TAP VALUE 1 = 0x2, 2 = 0x2 [0xadfa85da: 0xd6b9dbf9]                  
32 MB                                                                     
Top of RAM usable for U-Boot at: 82000000                                 
Reserving 283k for U-Boot at: 81fb8000
Reserving 192k for malloc() 
                            Reserving 44 Bytes for Board Info at: 81f87fd4

Reserving 36 Bytes for Global Data at: 81f87fb0                                       
                            Reserving 128k for boot params() at: 81f67fb0                                                                          

      Stack Pointer at: 81f67f98                                                


                                id read 0x100000ff                              

                                                  sector count = 64             

                                                                   Flash:  4 MB 

                                                                               In:    serial                                                                    
                                                                               Out:   serial                                                       
                                                       Err:   serial                                          

                                      Misc:  force GPIO1 output high            

                                                                    Net:   ag7240_enet_initialize...                                                            

                    Fetching MAC Address from 0x81fea470                        

                                                        Fetching MAC Address from 0x81fea470                                                                    

            Virian MDC CFG Value ==> 4                                          

                                      : cfg1 0xf cfg2 0x7014                    

                                                            eth0: 84:1b:5e:73:15:7d                                                                             

   eth0 up                                                                      

          Virian MDC CFG Value ==> 4                                            

                                    : cfg1 0xf cfg2 0x7214                      

                                                          eth1: 84:1b:5e:73:15:7c                                                                               

 ATHRS26: resetting s26                                                         

                       ATHRS26: s26 reset done                                  
                                              Trying eth1                       
                                                         eth1 link down         

                                                                       FAIL     

                                                                           Trying eth0                                                                          

      eth0 link down                                                            

                    FAIL                                                        




                        Retry count exceeded; boot the image as usual                                                                   
                        nmrp server is stopped or failed !                                                        

Although, I've edited the above to make it easier to read...it isn't coming in one character at a time, but it does seem to be displaying out of alignment.

I've also started receiving some sort of prompt, but I can't input into it, when I do the cursor starts flying across the screen...it looks like this:

Unknown command '^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G
^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G^G' - try 'help'






ar7240>    NTERRUPT>                                                                                            


                    Unknown command 'NTERRUPT>' - try 'help'                                                    

                                                            ar7240> ERRUPT>                                     


                                                                           Unknown command 'ERRUPT>' - try 'help'

                                                                                                                 ar7240> 


                                                                                                                         ar7240>  


                                                                                                                                  ar7240> 
leeand00
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2 Answers2

1

It looks like you need to add a newline character.

In Minicom settings select Screen and Keyboard and then experiment with the Add linefeed and Line Wrap options.

joan
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1

It does not look like a layer-1 (hardware) problem.

The first problem I see is that for each newline it only does a linefeed. In the little that I have used minicom, this was a constant battle. You need to tell it to convert incoming nl to cr, nl.

nl = newline character. cr = carriage return character.

ctrl-alt-delor
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