6.4. XModem source

The XModem source is treated differently to other sources. It provides a way to obtain files over a serial connection using the XModem protocol. The implementation of the XModem protocol within ABLE accepts 128byte or 1Kbyte packets and checksum or CRC16 checks.

The filename used with the XModem source is the serial port source on which to perform the transfer, these can be identified as aliases for char sources within a full source listing (see Example 6.1, “Using the ls command to list available sources.”). The parameters for a serial driver source are more fully described in Section 5.2, “Setting parameters on serial drivers”.

If the transfer is performed on the same source as is being used for the console care must be taken not to use commands which produce output during their reading of the file. Because of this the sum command may be used in its non verbose mode but would cause the transfer to fail if the -v option is used because it would output . characters to denote progress. Similarly the dumpfile and cat commands would cause a failure. Obviously this is not an issue if the transfer source is not used as a source for the console.

Example 6.4. Using the XModem source

This example shows a file being checksummed from the first S3C2410 serial port source. The C characters are the XModem receive characters signifying the start of the XModem sequence. The same file is then checksummed using the network interface to show the correctness of the transfer.

>sum (xmodem)s3c2410_serial0
39872 33 (xmodem)s3c2410_serial0
>sum (tftpboot)batty
39872 33 (tftpboot)batty