AT89C51RB2/RC2
ISP Protocol Description
Physical Layer
The UART used to transmit information has the following configuration:
•
•
•
•
•
Character: 8-bit data
Parity: none
Stop: 1 bit
Flow control: none
Baud rate: autobaud is performed by the bootloader to compute the baud rate
choosen 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 70. Intel Hex Type Frame
Record Mark ‘:’
Reclen
Load Offset
Record Type
Data or Info
Checksum
1 byte
1 byte
2 bytes
1 bytes
n byte
1 byte
•
•
Record Mark:
Record Mark is the start of frame. This field must contain ’:’.
Reclen:
Reclen 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 (see Section “ISP Commands Summary”).
•
•
•
Record Type:
–
Record Type specifies the command type. This field is used to interpret the
remaining information within the frame. The encoding for all the current
record types is described in Section “ISP Commands Summary”.
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 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.
95
4180E–8051–10/06
ATMEL [ ATMEL ]
