SPI FLASH Recovery/XO-4

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Contents

You Need

  • the bricked laptop, called the target, (which cannot be a B1 because the SPI FLASH operating voltage is 1.8V not 3.3V),
  • a working XO-1.5 laptop, with latest Firmware, and a serial cable, called the host,
  • a third computer to act as a terminal to the host, a serial cable, with serial port configured for 115200 bps,
  • wire, soldering iron, antistatic environment,
  • twelve pin headers, in four rows of three,
  • six 15cm lengths of female to female pin header jumper cables,

Setup

  • remove main battery and power cords from target and host laptops,
  • disassemble the target and host to PCB level,
  • place the PCBs upside down on a non-conductive but antistatic surface, with top edges close but not touching, adding insulation or adhesive if there is a risk of movement,
  • connect the serial cable between the host and the terminal and verify normal operation of the host, then turn off the host,
  • short the D4 component position next to J3 on the host, this provides 3.3V to J3 when the host is powered, but without protecting the host from power flowing from the target, be sure not to power the target,
  • add a 2K resistor between pins 1 and 2 of J3 on the host, this compensates for a weak pullup,
  • install pin headers on J3 on the host,
  • install pin headers on J2 on the target,
  • connect each pin of J3 on the host to J2 on the target in turn, using the jumper cables, pin 1 of J3 to pin 1 of J2,
  • add power cord to host only.

Transfer

  • turn on the host, while on the terminal use ESC to interrupt the host startup and obtain the Ok prompt,
ok
  • ensure the host is running Q3C12 plus svn 3622 or later,
  • configure the host SPI FLASH user interface for XO-4 SPI FLASH (after this, do not use it for reflashing of the host without first rebooting),
ok use-layout-xo-4
  • copy the SPI FLASH to a USB drive,
ok excavate u:\copy.rom
SPI FLASH is type 14.1540ef, W25Q16, 2 MB.
1fc000 
ok 
  • write the intended image,
ok recover u:\new.rom
Reading u:\new.rom
Got firmware version: CL4   Q7B27  Q7B
Checking integrity ...
SPI FLASH is type 14.1540ef, W25Q16, 2 MB.
Writing
1e0000 
Writing

Verifying
1e0000 
Verifying

ok 
  • turn off the host.
ok power-off

Testing

  • disconnect the cable between the target and the host,
  • attach serial cable to target,
  • attach power cable to target,
  • test the target by using ESC to obtain the Ok prompt.

Reasssembly

  • remove the header or ensure internal plastic is cut to permit it to remain.
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