Supporting ZSUN Wifi Card Reader (16MB Flash, 64MB RAM, AR9331)

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I have done the Recovery Mode feature to u-boot. I tested on my device and seems work well.

What's that:

A new feature of u-boot. By Inserting TF card during booting the device can boot to Recovery Mode, with basic wireless support and mtd command, so we can flash the firmware and bring the device back. It's alternatives of u-boot with Ethernet mode and web flash features.

NOTE: It's another new version of u-boot, pls follow the setps below and make sure you have flashed the new u-boot before flash rec series firmwares.

How to use it:

  1. Take the TF card out.
  2. Power up the zsun sdreader, LED start twinkling.
  3. Insert the TF card in 3 seconds.
  4. The LED stop twinkling for a while, then twinkling faster.
  5. After it stop twinkling again, connect the Wi-Fi 'OpenWrt'.
  6. Set the IP address to 192.168.1.2, subnet mask to 255.255.255.0.
  7. Connect the device by command telnet 192.168.1.1.
  8. cd to /tmp, download the firmware.
  9. Flash the firmware by command mtd write firmware.bin system

Follow the setps to flash it:

  1. Download this unlocked LEDE and flash it in luci.
  2. Download new u-boot to /tmp as uboot.bin, cd to /tmp in ssh.
  3. Flash the uboot by command mtd write uboot.bin u-boot
  4. Erase u-boot env by command mtd erase u-boot-env
  5. Download this Recovery Mode init firmware and flash it in luci.

Technical Details

It's mostly like recovery for android, a tiny dual system. When boot start up, if there is no TF card, it will wait for 3s for inserting it. If insert it will boot from recovery partition, otherwise keep doing normal boot. If normal boot faild it will automatically go to recovery mode.

By reduce 2MB from rootfs and change the range of firmware mtd partition, I create a new recovery partition after firmware.

The new mtdparts: 64k(u-boot)ro,64k(u-boot-env)ro,12032k(rootfs),2048k(kernel),2048k(recovery)ro,64k(nvram),64k(art),14080k@0x20000(firmware)

I build a openwrt 15.05 image with only basic wireless support(even dhcp is removed) to reduce the size under 2MB, then put it in.

Cause the recovery partition is out of firmware, it won't be flashed in the feature. I mark it read only also for safe.

The lede-unlocked.bin is a special firmware, with two kernel in 0x9FBE0000 and 0x9FEB0000.
The offical u-boot will boot from 0x9FEB0000
My old u-boot will boot from 0x9FEB0000 and 0x9FDE0000
The new u-boot will boot from 0x9FBE0000 and 0x9FDE0000
So it can be boot by all of those u-boot.

But after flash openwrt-18.06-rec_init.bin the recovery get out of firmware, if you want to get it back there is a lede-unlocked_rec.bin which can flash by luci.

NOTE: After flash the new uboot, you can't flash old firmware directly. The firmwares build from 18.06_rec is for the new u-boot. Firmware and imagebuilder will add to weekly building soon.

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