SPI FLASH Recovery for XO-1.75 Using CForth

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Revision as of 20:05, 21 July 2011 by Wmb@firmworks.com (talk | contribs) (Fixed horrible typo)
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If you have an XO-1.75 that will run CForth but will not run OFW, possibly because you are a firmware developer and have installed a test version whose OFW component is horribly broken, you can load a new version of OFW into the SPI FLASH from CForth.

Attach a serial port to your semi-dead XO-1.75.

Make sure your terminal emulator supports binary mode downloads. For minicom, this typically requires an auxiliary "bin-xfr" program - see http://dev.laptop.org/~wmb/bin-xfr.c , http://dev.laptop.org/~rsmith/bin-xfr.c , or see Using Minicom on an XO. For TeraTERM, check the Binary option in the Send File dialog.

Get into CForth by holding down the rotate key and powering on. 

 ok init-spi .spi-id
 ok 0810.0000 0800.0000 do key i c! loop
 <Send a rom image file, e.g. q4b03.rom, over serial, in binary mode>
 ok 0802.0000 e.0000 2.0000 reflash

The serial download takes just under 2 minutes (1 MiB at about 10,000 bytes/second). The reflash step takes about 20 seconds. If the download is taking much longer than 2 minutes, check to see if your terminal program adds "pacing" delays after each character. Pacing can make a large download take *forever*.

After that finishes you can power off and back on, and hopefully your machine will work.

The recipe above reflashes only the portion of the FLASH that contains OFW, leaving the (already working) CForth portion alone.

You can reflash the whole thing if you prefer, but I tend to be conservative in this state, not wanting to risk screwing up CForth. But for completeness, here is the recipe for reflashing the whole thing. Only the last command is different. 

 ok init-spi .spi-id
 ok 0810.0000 0800.0000 do key i c! loop
 <Send a rom image file, e.g. q4b03.rom, over serial, in binary mode>
 ok 0800.0000 10.0000 0 reflash

Using Minicom on an XO

First, install minicom: 

yum install minicom

Now install the binary transfer program: 

wget http://dev.laptop.org/~wad/bin-xfer
chmod a+x bin-xfer

Thanks to Danny Sung at http://www.dannysung.com/wmain/linux/tips/sending-binary-files-via-minicom/ for the script.

Attach a USB/serial adapter, and set up minicom to use it: 

olpc-nosleep sudo minicom -s USB0

You will need to change the serial port to be /dev/ttyUSB0.

You also need to change the “File transfer protocols”. You can add a section there called “binary”, point it at your file, and specify:

  • Name: Binary
  • Program: /home/olpc/bin-xfer -o %l
  • Name: Y
  • U/D: U
  • FullScr: Y
  • IO-Red: N
  • Multi:N

If you placed bin-xfer somewhere other than your home directory, don't forget to use the correct pathname! Save the configuration.

To send the binary file, type CTRL-A s and select Binary mode.

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