Linksys E7350 Serial Port Problem or downgrade method

Installing and Using OpenWrt
1

Hi there, I want my E7350 install OpenWRT, but the device installed the newest offical firmware already.
There has no method to downgrade firmware,but I took this page https://openwrt.org/toh/linksys/ea8500#changes_to_tftp_procedure_with_signed_linksysbelkin_firmwares I think mabay I can using U-Boot to fix firmware sign problem?

I tring to connect console, and find 5 pins try out 3 pin for Tx Rx and GND.
But here are some problem happend.
Using 115200 8N1,I got correct output but always send wrong input.
For example I press "1" the console will get "1g" or "2" get "23"(and enterkey) and arrow, enter key will not work.

Enable local echo for checking my KB not broken, connect RPi console checking my dongle run well.
Trying every baud rate or other option be sure in the right config.
I using Winddow Putty, Linux screen,minicom but get the same result.

What's problem about this situation?
I just want to install OpenWRT onto E7350 :frowning:

1 Like
2

You do not seem to be alone in this issue

4

I am wondering if we need to move this discussion to the "for developers" area for better exposure? There is a older thread for this model in that area already but it closed in September. Maybe that could be reopened instead of starting a new one?

5

Belkin RT1800 latest firmware is https://www.belkin.com/uk/support-article/?articleNum=208588

As the e7350 and rt1800 are identical can you downgrade to this.

6

So if you can get serial working properly, the boot loader allows uploading through tftp without a header. So sysupgrade image.

1 Like
7

I see the hint in this thread said "New replies are no longer allowed." I thinkg I can't reopen that thread :frowning:

I will get a try, but in console show that firmware will verify GPG sign,and the public key store in the runing firmware (or online URL) not uploading firmware file.

There is my secend problem,the console not works well.
Get the right output but wrong input,I can't choose the option I want in U-Boot menu as I mention at first post.

8

yeah I dunno. It worked for me when I tried it. /i use a cp2102 adapter.

1 Like
10

Tried this firmware and it gets to around 40% and then errors out saying upgrade failed.

11

Could you please post a better picture or a diagram of the pin connection layout for RX, TX, GND?

1 Like
13

Cool. I have a different 3.3v usb serial adapter so a diagram where to connect the Rx, Tx, and Gnd will work. I am holding on a bit though to see if there is another workaround rather than having to open up the unit.

1 Like
14

Are they prepopulated?

15

This is the usb-serial adapter cable that I have:link. It comes with a Tx, Rx, and Gnd connector which connect to the serial header on the router circuit board. Hopefully the router serial header is populated?

16

It is on these routers

17

are there detailed instructions anywhere I can add to the wiki?

18 
printenv
autostart=yes
baudrate=115200
boot_ver=V1.0
bootcmd=mtkautoboot
bootcount=10
bootdelay=0
bootfile=openwrt-ramips-mt7621-belkin_rt1800-squashfs-sysupgrade.bin
bootfile.firmware=openwrt-ramips-mt7621-belkin_rt1800-squashfs-factory.bin
bootimage=2
bootmenu_0=Startup system (Default)=mtkboardboot
bootmenu_1=Upgrade firmware=mtkupgrade fw
bootmenu_2=Upgrade bootloader=mtkupgrade bl
bootmenu_3=Upgrade bootloader (advanced mode)=mtkupgrade bladv
bootmenu_4=Load image=mtkload
bootmenu_5=Upgrade firmware with code pattern=mtkupgrade pfw
ethact=eth@1e100000
fdtcontroladdr=8ffece60
fileaddr=80010000
filesize=69cc35
ipaddr=192.168.1.1
loadaddr=0x80010000
mtddevname=u-boot
mtddevnum=0
mtdids=nand0=ranand
mtdparts=mtdparts=ranand:512k(u-boot),512k(u-boot-env),512k(factory),48m(firmware),-(firmware_2)
netmask=255.255.255.0
partition=nand0,0
serverip=192.168.1.2
stderr=uartlite0@1e000c00
stdin=uartlite0@1e000c00
stdout=uartlite0@1e000c00

so installing factory.bin via web interface does not work, tried both available rt1800 firmware.
Trying to tftpboot the current snapshot, error cant find kernel.

Saving Environment to NAND... Erasing NAND...
Erasing at 0x80000 -- 100% complete.
Writing to NAND... OK
OK
#####CBT_BOOT_VERSION=[V1.0]######
#####boot_count=[11] boot_part=[1] boot_change=[1]######

Loading from nand0, offset 0x180000
** Unknown image type
no partition number specified

Loading from nand0, offset 0x180000
** Unknown image type
=>

so could someone advise how to get out of uboot please

19

dont connect GND until after initial boot up

So the error message when tftpbooting is can't find kernel.
Doesn't matter what I try.

Can someone tell me if my uboot printenv is correct?
This was from today's snapshot, tried both sysupgrade and factory images.

Anyone have a working version as snapshot could be broken.

tftpboot
Using eth@1e100000 device
TFTP from server 192.168.1.2; our IP address is 192.168.1.1
Filename 'openwrt-ramips-mt7621-belkin_rt1800-squashfs-sysupgrade.bin'.
Load address: 0x80010000
Loading: T #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 ##################
	 433.6 KiB/s
done
Bytes transferred = 6933557 (69cc35 hex)
Automatic boot of image at addr 0x80010000 ...
Wrong Image Format for tftpboot command
ERROR: can't get kernel image!

git commit from @neheb matches what is trying to load

*** Loading image ***

Input load address: 0x80010000

Available load methods:
    0 - TFTP client (Default)
    1 - Xmodem
    2 - Ymodem
    3 - Kermit
    4 - S-Record

Select (enter for default): 0

Input U-Boot's IP address: 192.168.1.1
Input TFTP server's IP address: 192.168.1.2
Input IP netmask: 255.255.255.0
Input file name: sysupgrade.img                                             

Using eth@1e100000 device
TFTP from server 192.168.1.2; our IP address is 192.168.1.1
Filename 'sysupgrade.img'.
Load address: 0x80010000
Loading: T #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 #################################################################
	 ##################
	 1.2 MiB/s
done
Bytes transferred = 6933557 (69cc35 hex)

*** Loaded 6933557 (0x69cc35) bytes at 0x80010000 ***

Run loaded data now? (Y/n): y
Wrong Image Format for <NULL> command
ERROR: can't get kernel image!
20

Very strange. My RT1800 is in production right now so I can’t really do any testing.

My advice currently is to try flashing stock firmware, as old as possible and try flashing the factory. After two reboots of course.

21

Well that was a painful learning experience,

tl;dr tftpboot the belkin_rt1800-initramfs-kernel.bin

after that flash sysupgrade after scp it to the device.

@neheb my firmware version is FW_RT1800_V1.1.00.005, it's probably something ancient in the firmware causing the issue.

22

My RT1800 arrived with "Current firmware version: 1.0.00.005"
Updated it with FW_RT1800_V1.1.00.016_Prod_20210723_code.bin
Web interface showed "Firmware Version 1.1.00 build 16 Jul 23, 2021"
Then upgraded it with -factory.bin first, then finally with -sysupgrade.bin (built with Luci) using scp/ssh.

23

Nice to know you have a -factory.bin that works, can you share it?