[RT-AC56U] Reboot cycle after update to original firmware 374.291

[ScipioWarrior]

Hi! I ordered the USB to TTL cable, this one to be exact, and followed the instructions on the previous page. I can get PuTTY to recognize and connect to the cable and open a window, but after turning on the router nothing shows up in the window. Something is definitely recognized on the router side because all of the lights on the LAN ports stay lit, which is not normal behavior. Here is how I have it connected in case that is the issue:

Thanks for any help!

 

[RMerlin]

Hi! I ordered the USB to TTL cable, this one to be exact, and followed the instructions on the previous page. I can get PuTTY to recognize and connect to the cable and open a window, but after turning on the router nothing shows up in the window. Something is definitely recognized on the router side because all of the lights on the LAN ports stay lit, which is not normal behavior. Here is how I have it connected in case that is the issue:

Thanks for any help!

If nothing shows up then one of the following must be the problem:

1) You have inverted TX and RX - try swapping them
2) You have the wrong serial parameters (should be 115200, 8N1, None)
3) Your serial adapter doesn't work or is not compatible (make sure it's design to support 3.3V level signaling)
4) Your bootloader is toasted, and the router fails to even start booting

Based on the LED pattern, if the same issue occurs even without the serial adapter connected, then the router's bootloader or HW is probably toast.

 

[ScipioWarrior]

If nothing shows up then one of the following must be the problem:

1) You have inverted TX and RX - try swapping them
2) You have the wrong serial parameters (should be 115200, 8N1, None)
3) Your serial adapter doesn't work or is not compatible (make sure it's design to support 3.3V level signaling)
4) Your bootloader is toasted, and the router fails to even start booting

Based on the LED pattern, if the same issue occurs even without the serial adapter connected, then the router's bootloader or HW is probably toast.

OK, I swapped the TX and RX and stuff is showing up in the PuTTY window. This is what it says:

Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 800MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Null Rescue Flag.
boot the image...
go load
Loader:raw Filesys:tftp Dev:(null) File:: Options:(null)
Loading: TFTP Server.
Failed.
Could not load :: Error
Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)
Loading: .... 4171200 bytes read
Entry at 0x00008000
Starting program at 0x00008000
console [ttyS0] enabled, bootconsole disabled
serial8250.0: ttyS1 at MMIO 0x18000400 (irq = 117) is a 16550
brd: module loaded
loop: module loaded
pflash: found no supported devices
bcmsflash: found no supported devices
Boot partition size = 524288(0x80000)
lookup_nflash_rootfs_offset: offset = 0x200000
nflash: squash filesystem with lzma found at block 29
Creating 4 MTD partitions on "nflash":
0x000000000000-0x000000080000 : "boot"
0x000000080000-0x000000200000 : "nvram"
0x000000200000-0x000002000000 : "linux"
0x0000003aa834-0x000002000000 : "rootfs"
PPP generic driver version 2.4.2
PPP MPPE Compression module registered
NET: Registered protocol family 24
PPTP driver version 0.8.5
=== PPTP init ===
u32 classifier
    Actions configured
Netfilter messages via NETLINK v0.30.
nf_conntrack version 0.5.0 (3990 buckets, 15960 max)
xt_time: kernel timezone is -0000
ip_tables: (C) 2000-2006 Netfilter Core Team
TCP cubic registered
NET: Registered protocol family 10
ip6_tables: (C) 2000-2006 Netfilter Core Team
NET: Registered protocol family 17
L2TP core driver, V2.0
PPPoL2TP kernel driver, V2.0
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
Registering the dns_resolver key type
Restarting system.

And then it repeats. The issue I'm having now is that it isn't responding to ctrl c. If I hold it down while the router is off a blue LED nest to "TXD" blinks rapidly, but as soon as I turn it on it ceases blinking and the CFE> prompt never shows up.

 

[RMerlin]

And then it repeats. The issue I'm having now is that it isn't responding to ctrl c. If I hold it down while the router is off a blue LED nest to "TXD" blinks rapidly, but as soon as I turn it on it ceases blinking and the CFE> prompt never shows up.

Keep Ctrl-C pressed after your turned it on, and give it at least 30 secs. Before it starts loading the kernel, it should finally manage to break the CFE boot process and give you CFE access.

If it still fails, you could try increasing your keyboard's key repeat speed in Windows' control panel. I have no idea how small the opportunity window is for breaking the CFE boot process, but it's quite small.

 

[ScipioWarrior]

Keep Ctrl-C pressed after your turned it on, and give it at least 30 secs. Before it starts loading the kernel, it should finally manage to break the CFE boot process and give you CFE access.

If it still fails, you could try increasing your keyboard's key repeat speed in Windows' control panel. I have no idea how small the opportunity window is for breaking the CFE boot process, but it's quite small.

After keeping ctrl c pressed for minutes at a time, it still hasn't given me CFE access. I decided to compare my output to MickeyRooney's earlier in the thread, and they're noticeably different. You can see the differences at this link: https://www.diffchecker.com/1bikhjb7

Not only does his output have a large section at the beginning that mine doesn't have, but the rootfs partition is labeled differently and most notably mine seems to restart before his does. This is the output at the end for his that isn't present in mine:

Northstar brcmnand NAND Flash Controller driver, Version 0.1 (c) Broadcom Inc. 2012	68	Restarting system. 
181	NAND device: Manufacturer ID: 0x01, Chip ID: 0xf1 (AMD NAND 128MiB 3,3V 8-bit) 	 	
182	Spare area=64 eccbytes 56, ecc bytes located at: 	 	
183	 2 3 4 5 6 7 8 9 10 11 12 13 14 15 18 19 20 21 22 23 24 25 26 27 28 29 30 31 34 35 36 37 38 39 40 41 42 43 44 45 46 47 50 51 52 53 54 55 56 57 58 59 60 61 62 63 	 	
184	Available 7 bytes at (off,len): 	 	
185	(1,1) (16,2) (32,2) (48,2) (0,0) (0,0) (0,0) (0,0) 	 	
186	Scanning device for bad blocks 	 	
187	Options: NO_AUTOINCR,NO_READRDY,BBT_SCAN2NDPAGE, 	 	
188	Creating 2 MTD partitions on "brcmnand": 	 	
189	0x000002000000-0x000008000000 : "brcmnand" 	 	
190	0x000004000000-0x000006000000 : "jffs2" 	 	
191	VFS: Mounted root (squashfs filesystem) readonly on device 31:3. 	 	
192	devtmpfs: mounted 	 	
193	Freeing init memory: 216K

 

[RMerlin]

If you reach the NAND driver as shown above then it's too late and you are already past the bootloader and into the kernel.

Sent from my Nexus 4 using Tapatalk

 

[ScipioWarrior]

If you reach the NAND driver as shown above then it's too late and you are already past the bootloader and into the kernel.

Sent from my Nexus 4 using Tapatalk

Even if I completely leave it alone, it never reaches the NAND driver - it still restarts right before it would show up.

 

[RMerlin]

Even if I completely leave it alone, it never reaches the NAND driver - it still restarts right before it would show up.

Once you reach

Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)

then you are leaving the CFE environment and starting to boot the Linux kernel.

Try increasing your keyboard repeat speed as suggested, and double check that the rx and tx lines are properly connected.

 

[ScipioWarrior]

Once you reach

Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)

then you are leaving the CFE environment and starting to boot the Linux kernel.

Try increasing your keyboard repeat speed as suggested, and double check that the rx and tx lines are properly connected.

OK, I'm pretty certain at this point that there is an issue with the adapter or the router. Switching TX and RX causes the LAN port lights to stay lit and increasing the key speed doesn't help. Is there anyway to confirm there is definitely an issue with the adapter before I go and order a different one? Or is there something I'm missing?

 

[SkyKilla]

I tried doing nvram erase and then nvram commit and rebooting, but it didn't seem to work since I still can't get into recovery mode using WPS and reset buttons. Neither is eth0 configuration mentioned anywhere during startup.

Other way, but I get same symptoms. Web GUI wasn't start after firmware flashing. Telnet on 192.168.1.1 was still accesible and I decided to clear nvram, giving commands:
....
nvram erase
nvam commit
reboot
(did it several times before in same situations)
....
and get "reboot cycle hell". Now, I'm affraid, nvram cleanig (even via usb-to-ttl cable) will take no effect.

 

[roundaway]

Very much appreciate the detailed directions to recover a bad flash.

Flashed a different firmware without erasing nvram before and locked it up. Steady power light and send/receive lights on the back. Could never get it to recovery mode. Ordered a cable and connected using the guidance here. First time the TX and RXD were reversed. Second time money! Appreciate everyone sharing there troubles and how they fixed them. Thanks RMerlin for great firmware and ability to help us noobs.

P.S. If someone above hadn't mentioned the two screws on the backside of the router I never would have looked/felt. I thought the ASUS text info was silkscreened on the plastic. Turns out to be a semi-rigid plastic label. You can press with your fingers to find the holes. The one above the power button has a paper VOID Warranty so I just pressed harder with the screw driver.

 

[leoo2001]

Sorry to revive this old tread but after unsuccesufull flash of Merlin 380.58 Im expiriencing the same issues like MikeyRooney and SkyKilla and the logs are similar. I have prolific pl2303 serial adapter that connects withoutut issues, but no mather how many times i did nvram reset command trough putty, cfe always fails to initialize ethernet and cannot go into recovery mode or flash new firmware. Code: nvram set vlan1ports="1 2 3 4 8*" dont seems to help either.
If someone have found workarround please share. Im without internet and have to wait untill Monday to buy a new router. The wife will kill me....

 

[kikiqqp]

1. download merlin firmware 378.56_2 or ASUS RT-AC56U firmware 3.0.0.4.378.9459
2. download reply programs 2.0.0, can be found in the package cd-rom discs or here
3. off your AC56U router power
4. get net cable(RJ45 cable) comm to AC56U
5. set your computer ip 192.168.1.1 and subnet mask 255.255.255.0
6. press the reset button (between the power button and USB) and press the power button
7. your AC56U power led are flash
8. open reply programs 2.0.0, set firmware reply it

This recovery, but then if you upgrade the new version merlin firmware of the same mistakes, I suspect asus have some lowquality eeprom memory to AC56U

 

[nikuz]

Hello. Can somebody help me?

I tried the commands in sequence:
1) nvram erase
2) nvram commit
3) reboot (or power off / power on)

But it didn't help me. Still cycle rebooting.

This is my serial output log:

Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 800MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Null Rescue Flag.
boot the image...
go load
Loader:raw Filesys:tftp Dev:(null) File:: Options:(null)
Loading: TFTP Server.
Failed.
Could not load :: Error
Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)
Loading: .... 4026368 bytes read
Entry at 0x00008000
Starting program at 0x00008000
console [ttyS0] enabled, bootconsole disabled
serial8250.0: ttyS1 at MMIO 0x18000400 (irq = 117) is a 16550
brd: module loaded
loop: module loaded
pflash: found no supported devices
bcmsflash: found no supported devices
Boot partition size = 524288(0x80000)
lookup_nflash_rootfs_offset: offset = 0x200000
nflash: squash filesystem with lzma found at block 28
Creating 4 MTD partitions on "nflash":
0x000000000000-0x000000080000 : "boot"
0x000000080000-0x000000200000 : "nvram"
0x000000200000-0x000004000000 : "linux"
0x00000039a814-0x000004000000 : "rootfs"
PPP generic driver version 2.4.2
PPP MPPE Compression module registered
NET: Registered protocol family 24
PPTP driver version 0.8.5
u32 classifier
    Actions configured
Netfilter messages via NETLINK v0.30.
nf_conntrack version 0.5.0 (3992 buckets, 15968 max)
xt_time: kernel timezone is -0000
ip_tables: (C) 2000-2006 Netfilter Core Team
TCP cubic registered
NET: Registered protocol family 10
ip6_tables: (C) 2000-2006 Netfilter Core Team
NET: Registered protocol family 17
L2TP core driver, V2.0
PPPoL2TP kernel driver, V2.0
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
Registering the dns_resolver key type
Restarting system.

So, i can't initialize bootloader mode and i can't restore firmware via TFTP.

 

[leoo2001]

I had similar problem and after a week of investigation and trying, ended buying a new (better) router. Looks like bootloader of AC56U is real junk. Probably is doable with a JTAG, but I didn't find much information how to do it. In my case the serial cable was useful only to read the logs , none of the nvram commands didn't effect.

 

[nikuz]

Hi Leoo2001,

I also note that nvram show command will get the same data always, even after nvram erase and nvram commit. Looks like commands take no effect.

I use this TTL to USB adapter:
http://www.aliexpress.com/item/2pcs...th-Free-cable-Dust-proof-Cover/748107716.html

Driver is here:
http://www.prolific.com.tw/US/ShowProduct.aspx?pcid=41&showlevel=0041-0041

 

[leoo2001]

I already have TTL to USB adapter that I managed to work with Windows 10 without any issues. The thing is that we are talking about serial adapter and what may get back to live our routers is JTAG box, but looks like that there is not ARM drivers available. More information about Jtag and serial ports in this thread

http://www.snbforums.com/threads/pins-on-rt-ac56u.18211/

 

[nikuz]

Oh, it's really sad. It was good router. And it's not cheap to buy the new one like this one

 

[nikuz]

Hi,

I finally got the full linux console on my RT-AC56U. Problem was with specific entries in my nvram. When i tried to get all content from the nvram by nvram show, my console freezes on specific entries with ssh keys:
vpn_crt_server1_client_crt
vpn_crt_server1_crt
sshd_authkeys
sshd_hostkey
vpn_crt_server1_client_key
vpn_crt_server1_key
vpn_crt_server1_ca_key

So, i just tried to remove this entries by nvram unset. Like:
nvram unset vpn_crt_server1_client_crt
etc.

After that i tried to get full nvram content by nvram show. My console didn't freeze anymore and i got the content. Then i tried again nvram erase and nvram commit. And finally reboot.

And, as i said before, i got full linux console. I can check file system, devices, ifconfig finally shows me ip address and other parameters.

Right now i do not have PC with Ethernet port, so i can't connect to the router for update firmware. I will try to do it tomorrow.

 

[silentwolf]

1. download merlin firmware 378.56_2 or ASUS RT-AC56U firmware 3.0.0.4.378.9459
2. download reply programs 2.0.0, can be found in the package cd-rom discs or here
3. off your AC56U router power
4. get net cable(RJ45 cable) comm to AC56U
5. set your computer ip 192.168.1.1 and subnet mask 255.255.255.0
6. press the reset button (between the power button and USB) and press the power button
7. your AC56U power led are flash
8. open reply programs 2.0.0, set firmware reply it

This recovery, but then if you upgrade the new version merlin firmware of the same mistakes, I suspect asus have some lowquality eeprom memory to AC56U

hi，do you successfully upgraded to 380.59 on your AC56U？