Rainbow Electronics AT91CAP9S250A - Manual (Page 80)

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6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
– Output: The byte, halfword or word read in hexadecimal following by ‘>’
• Send a file (S): Send a file to a specified address
– Address: Address in hexadecimal
– Output: ‘>’.
Note: There is a time-out on this command which is reached when the prompt ‘>’ appears before the
end of the command execution.
• Receive a file (R): Receive data into a file from a specified address
– Address: Address in hexadecimal
– NbOfBytes : Number of bytes in hexadecimal to receive
– Output: ‘>’
• Go (G): Jump to a specified address and execute the code
– Address: Address to jump in hexadecimal
– Output: ‘>’
• Get Version (V): Return the SAM-BA boot version
– Output: ‘>’
14.6.1 DBGU Serial Port
Communication is performed through the DBGU serial port initialized to 115200 Baud, 8, n, 1.
The Send and Receive File commands use the Xmodem protocol to communicate. Any termi-
nal performing this protocol can be used to send the application file to the target. The size of
the binary file to send depends on the SRAM size embedded in the product. In all cases, the
size of the binary file must be lower than the SRAM size because the Xmodem protocol
requires some SRAM memory to work.
14.6.2 Xmodem Protocol
The Xmodem protocol supported is the 128-byte length block. This protocol uses a two-char-
acter CRC-16 to guarantee detection of a maximum bit error.
Xmodem protocol with CRC is accurate provided both sender and receiver report successful
transmission. Each block of the transfer looks like:
<SOH><blk #><255-blk #><--128 data bytes--><checksum> in which:
– <SOH> = 01 hex
– <blk #> = binary number, starts at 01, increments by 1, and wraps 0FFH to 00H
(not to 01)
– <255-blk #> = 1’s complement of the blk#.
– <checksum> = 2 bytes CRC16
Figure 14-7 shows a transmission using this protocol.