Archer C2 v1.1 blank MAC address after debrick

Installing and Using OpenWrt
1

Hello guys,

First of all, let me explain the problem step by step.

  1. After various flashs of OpenWRT, OEM firmware, I bricked Archer C2. not booting, TFTP recovery not working anymore. I'v read somewhere that the u-boot chip has been erased.
  2. I managed to debrick Archer C2 by re-flash u-boot using CH341A chip programmer, resolder it back on board. Flashed OEM firmware in TFTP, rounter boots and became working again.

However, I found out that Wireless (both 2.4G/5G)is not working, because no MAC address was detected for wireless module.

Can somebody guide me on how to restore the MAC address in order for Wireless to work again? Thank you in advance.

2

You need to restore not only u-boot but "radio" flash partition too. This partition of size 64k (0x10000 in hex) resides at offset 0x7f0000 of flash.

3

Thank you for your response Serge.
Is this partition part of u-boot program inside the Winbond chip?

Sorry I am new into Openwrt, can you help me by give some guide on what should I do to restore this partition and regain wireless function?

5

In this file (device config description)


you can see flash layout.
You need to update "radio" partition 
			radio: partition@7f0000 {
				label = "radio";
				reg = <0x7f0000 0x10000>;
				read-only;
			};

with your eeprom containing calibration info and mac address for internal wifi

&wmac {
	ralink,mtd-eeprom = <&radio 0x0>;
};

and external 5G wifi

&pcie0 {
	wifi: mt76@0,0 {
		reg = <0x0000 0 0 0 0>;
		mediatek,mtd-eeprom = <&radio 0x8000>;
		ieee80211-freq-limit = <5000000 6000000>;
	};
};

In openwrt command line it may be done with commands:

opkg update
opkg install kmod-mtd-rw
insmod mtd-rw i_want_a_brick=1
mtd unlock radio
mtd write radio.bin radio

where radio.bin is your data copied to device before procedure.
radio.bin may be obtained from the dump of original flash:

dd if=original_flash.dump of=radio.bin bs=64k skip=127

If you didn't save original flash dump than you may use any dump from the same device model but you lose original wifi mac addresses in this case.

1 Like
6

Thank you again for spend your time to help.

I kept a record of all MAC addresses of our home devices, but I don't have original dump file. Can I use dump from same device and and edit MAC address in any binary editor?

7

Yes.
2.4G mac offset is 0x4 and 5G mac offset is 0x8004 in radio.bin

8

Although im not sure what to do with the source code you posted above, I will do some searches. :grinning:
Will keep you updated after some attempts.

9

I wanna say THANK YOU SO MUCH! After some searches, I managed to find a dump, dd out the radio.bin, changed MAC in Hex editor. upload to OpenWRT through SHH, execute the commands you given. Now it worked!!! Thank you again, you are my hero and saved my day! :kissing_heart: :kissing_heart: :kissing_heart: