at89c51snd1c ATMEL Corporation, at89c51snd1c Datasheet - Page 8

• Manufacturer Part Number: at89c51snd1c
• Description: At89c51snd1c At89c51snd1 Uart Bootloader
• Manufacturer: ATMEL Corporation

Physical Layer
Frame Description
8
AT89C51SND1 UART Bootloader
The UART used to transmit information has the following configuration:
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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 in Table 4.
Table 4. Intel Hex Type Frame
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Record Mark ‘:’
Character: 8-bit data
Parity: none
Stop: 1 bit
Flow control: none
Baud rate: auto baud is performed by the bootloader to compute the baud rate
chosen by the host.
Record Mark:
–
Record length:
–
Load Offset:
–
Record Type:
–
Data/Info:
–
Checksum:
–
1 byte
Record Mark is the start of frame. This field must contain “:”.
Record length specifies the number of Bytes of information or data which
follows the Record Type field.
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 specifies the command type. This field is used to interpret the
remaining information within the frame.
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.
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 include the Record Length
field to the last Byte of the Data/Info field inclusive. Therefore, the sum of all the
ASCII pairs in a record after converting to binary, from the Record Length field
to and the Checksum field inclusive, is zero.
Record length
1 byte
Load Offset
2 bytes
Record Type
1 byte
Data or Info
n byte
4241B–MP3–07/04
Checksum
1 byte