Scenario: You accidentally flashed the wrong OpenWRT image to your VoCore, and it is now stuck in a boot loop.
At this point, the only way to fix, as outlined here http://vocore.io/wiki/index/id:14 is to use the TTL adapter.
Once I connected via the TTL, sure enough i could see u-boot struggling with the linux partition on the flash, and continually resetting the board.
Following the instructions to send the vocore.dock2.bin file (the correct rom for the vocore with dock) i found that the instructions to then write the image to flash from uBoot did not seem to work, and it returned
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Booting image at bc050000 .
Image Name: MIPS OpenWrt Linux-3.10.49
Created: 2015-11-25 4:21:27 UTC
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 1010595 Bytes = 986.9 kB
Load Address: 80000000
Entry Point: 80000000
Load Kernel: ................
Verifying Checksum ... Bad Data CRC
What i did instead was then type bootm which makes the vocore boot from the file we sent it, from RAM instead of booting from flash
at this point, you can observe the vocore booting OpenWRT, and after a minute or so, the VoCore Wireless network will become avaiable.
I connected to that from my laptop, and used the luci web interface (http://192.168.61.1/ ) to re-flash the correct rom file (vocore.dock2.bin in my case) and waited for the process to complete.
Once it had rebooted back in to OpenWRT, I confirmed that it was able to boot on it's own by observing the console and power cycling the device and waiting for OpenWRT to finish booting, and sure enough the process seems to have unbricked the vocore. at this point I detached the serial console and power and re-attached the dock, and everything seems to be working normally.
Hope this helps someone!
Edit: Here are the commands I entered in sequence to perform the above operation
First insert the USB TTL adapter and connect it to the VoCore
Open Up a terminal and enter the following commands (I did this from MacOSX but it should be the same for Linux Users)
first place your firmware image (vocore.dock2.bin) in your home directory, and/or make sure your command line is in the same folder as the rom file you need to send the vocore.
(you can use pwd and ls to verify this)
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kermit
then from kermit entered the following
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set line /dev/tty.usbserial
define sz !sz \%0 > /dev/tty.usbserial < /dev/tty.usbserial
set speed 57600
set carrier-watch off
set prefixing all
set parity none
set stop-bits 1
set modem none
set file type bin
set file name lit
set flow-control none
set prompt “MacOS Kermit> ”
then powered up the VoCore and waited for the boot loader to start appearing, if it does not, try hitting return a couple of times or check the connection and installed drivers for your TTL adapter, if it is connected you should see a light flickering on the adapter (a red one if supplied by Vonger with your VoCore). If the blue light is flickering you may have it connected wrong (it should be Tx to Rx and Rx to Tx)
once u-boot started scrolling up the screen, hit x repeatedly until it drops you in to a command prompt for u-boot, it should appear as
VoCore>
this step may take a few attempts
now enter the following:
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loadb
to put u-boot in to the appropriate mode to receive the new rom file
then press the following key combos
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CTRL+/ followed by C
to return to kermit locally without terminating the connection
then enter the following:
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send vocore.dock2.bin
You should see the following screen
wait for the process to complete (it can take 10-15 minutes)
then enter
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connect
to return to u-boot
At this point you can either attempt to flash the file directly, but this can be complicated, and as I mentioned above I had issues with this. The easyest and probably safer option is to boot the new rom directly from RAM, to do this,
enter
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bootm
and observe as openwrt begins booting.
eventually you should see the OpenWRT command line appear by hitting enter a few times, by which time you can now connect to the VoCore via the built in WiFi (it should be an open network called VoCore_xxxx or OpenWRT) and log in to Luci with the user root and password vocore
and navigate your way to the luci firmware update page (System -> Backup/Flash Firmware) and upload the vocore.dock2.bin file and follow standard procedure.
once it is done, you should find the VoCore can now boot on it's own.
Good Luck!
(some useful links)
[url]vonger.cn/upload/firmware/vocore.dock2.bin[/url] Vonger's ROM build for the dock2
https://downloads.openwrt.org/barrier_breaker/14.07/ramips/rt305x/ correct version of OpenWRT for Ramips rt305x (look for openwrt-ramips-rt305x-vocore-squashfs-sysupgrade.bin)
http://vonger.cn/?p=780 the post i based most of this process off