upc2

upc2 is a replacement for the venerable upc terminal program Kynesim uses to boot things. It is a combined bootloader and console with a flexible and extensible set of protocols, and can easily handle multi-stage boots.

Usage

upc2 [--help] [--serial <device>] [--log <filename>] <boot-stage>*
        [--script <filename>] [<baud>]

  --help              Outputs a syntax help message.
  --serial <device>   Specifies the serial device to communicate with,
                      by default "/dev/ttyUSB0".
  --log <filename>    Logs output from the serial connection to the
                      named file.  Does not log console input sent to
                      the serial connection.  Protocol handshakes may
                      be omitted depending on the protocol.
  --script <filename> Reads the named file as if its contents were more
                      command-line parameters
  <baud>              The baud rate used for serial communications once
                      all uploads have been completed.  If omitted, a
                      baud rate of 115200 will be used.
  <boot-stage>        Stages of booting are specified by a sequence of
                      command-line arguments:
    --grouch <filename>  The file to upload.  This is the first
                         argument of any boot stage.
    --baud <baud>        The serial baud rate to use for this boot
                         stage.  The first boot stage defaults to a
                         115200 baud rate; subsequent boot stages
                         default to the baud rate of the previous
                         stage.
    --protocol <name>    The protocol to use to upload the file.  At
                         present two protocols are supported;
                         "grouch", a simple in-house protocol, and
                         "xmodem", the venerable XMODEM protocol.
                         The protocol defaults to "grouch".
    --defer              Drop into console mode to allow user
                         intervention.  Upload is continued by the
                         escape sequence `C-a c`

Baud rates can be abbreviated with "k" for kilobaud and "m" for megabaud, so 1 megabaud can be specified as "1m".

For example, imagine a device with a two-stage boot connected to /dev/ttyUSB1. The first stage is a file "hub.bin" sent using XModem at 115200 baud. The second stage is a file "nfs.cpio" sent using grouch at 1 megabaud. The final result should be give a serial terminal at 115200 baud again. The up2c command line for this is:

upc2 --serial /dev/ttyUSB1 \
  --grouch /path/to/hub.bin --protocol xmodem --baud 115200 \
  --grouch /path/to/nfs.cpio --protocol grouch --baud 1m \
  115200

Keyboard handling

Uploads can be interrupted by the key sequence C-a x, which will cause upc2 to quit.

During uploads, input from the console is not passed through to the serial connection. Once the uploads are complete, the serial connection is switched to the specified baud rate and upc2 becomes a console program. Commands are given to the program through escape key sequences beginning with a C-a:

• C-a x Quits upc2
• C-a h Prints a console help message
• C-a C-a Sends a C-a through the serial connection
• C-a l Lists the boot stages
• C-a c Continues a deferred upload (see --defer above)
• C-a <digit> Selects the boot stage numbered <digit> when in console mode. Does not immediately start the upload.
• C-a n Selects the next boot stage when in console mode.
• C-a p Selects the previous boot stage when in console mode.

Other escape sequences may be added as needed, so users should not expect C-a <key> to send <key> to the serial connection without checking. Traps have been laid for the excessively bold.

[email protected] 2015-12-01

[email protected] 2015-12-02