Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet
Product codes
AT91SAM9N12-EK
104
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
12.2.5.2 DBGU Serial Port
Communication is performed through the DBGU serial port initialized to 115,200 Baud, 8 bits of data, no parity, 1 stop bit.
Supported External Crystal/External Clocks
The SAM-BA Monitor supports a frequency of 12 MHz to allow DBGU communication for both external crystal and
external clock.
external clock.
Xmodem Protocol
The Send and Receive File commands use the Xmodem protocol to communicate. Any terminal 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 in order to work.
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 in order to work.
The Xmodem protocol supported is the 128-byte length block. This protocol uses a two-character CRC16 to guarantee
detection of a maximum bit error.
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:
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
shows a transmission using this protocol.
Figure 12-11. Xmodem Transfer Example
Host
Device
SOH 01 FE Data[128] CRC CRC
C
ACK
SOH 02 FD Data[128] CRC CRC
ACK
SOH 03 FC Data[100] CRC CRC
ACK
EOT
ACK