Datasheet

7
4266C–CAN–03/08
AT89C51CC03 UART Bootloader
Physical Layer The UART used to transmit information has the following configuration:
• Character: 8-bit data
• Parity: none
• Stop: 2 bits
• Flow control: none
• Baud rate: autobaud is performed by the bootloader to compute the baud rate chosen by the
host.
Frame Description The Serial Protocol is based on the Intel Hex-type records.
Intel Hex records consist of ASCII characters used to represent hexadecimal values and are
summarized below.
Table 1. Intel Hex Type Frame
• Record Mark:
– Record Mark is the start of frame. This field must contain ’:’.
• Record length:
– Record length specifies the number of Bytes of information or data which follows the
Record Type field of the record.
• Load Offset:
– Load Offset specifies the 16-bit starting load offset of the data Bytes, therefore this
field is used only for
– Data Program Record.
• Record Type:
– Record Type specifies the command type. This field is used to interpret the
remaining information within the frame.
• Data/Info:
– Data/Info is a variable length field. It consists of zero or more Bytes encoded as pairs
of hexadecimal digits. The meaning of data depends on the Record Type.
• Checksum:
– The two’s complement of the 8-bit Bytes that result from converting each pair of
ASCII hexadecimal digits to one Byte of binary, and including the Record Length field
to and including the last Byte of the Data/Info field. Therefore, the sum of all the
ASCII pairs in a record after converting to binary, from the Record Length field to and
including the Checksum field, is zero.
Record Mark ‘:’ Record length Load Offset Record Type Data or Info Checksum
1 byte 1 byte 2 bytes 1 bytes n byte 1 byte