at89c51rd2-smsum ATMEL Corporation, at89c51rd2-smsum Datasheet - Page 102

• Manufacturer Part Number: at89c51rd2-smsum
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

24.7
24.7.1
24.7.2
102
ISP Protocol Description
AT89C51RD2/ED2
Physical Layer
Frame Description
The UART used to transmit information has the following configuration:
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.
Figure 24-6. Intel Hex Type Frame
Record Mark is the start of frame. This field must contain ’:’.
Reclen specifies the number of bytes of information or data which follows the Record Type field
of the record.
Load Offset specifies the 16-bit starting load offset of the data bytes, therefore this field is used
only for Data Program Record (see Section “ISP Commands Summary”).
Record Type specifies the command type. This field is used to interpret the remaining informa-
tion within the frame. The encoding for all the current record types is described in Section “ISP
Commands Summary”.
Data/Info is a variable length field. It consists of zero or more bytes encoded as pairs of hexa-
decimal 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 hexadec-
imal digits to one byte of binary, and including the Reclen 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 Reclen field to and including the Checksum field, is zero.
• Character: 8-bit data
• Parity: none
• Stop: 2 bits
• Flow control: none
• Baudrate: autobaud is performed by the bootloader to compute the baudrate chosen by the
• Record Mark:
• Reclen:
• Load Offset:
• Record Type:
• Data/Info:
• Checksum:
host.
Record
1-byte
Mark
’:’
Reclen
1-byte
2-bytes
Load
Offset
1-byte
Record
Type
n-bytes
Data
Info
or
Checksum
1-byte
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