AT89C51AC2(2005) Просмотр технического описания (PDF) - Atmel Corporation

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Компоненты Описание

производитель

AT89C51AC2
(Rev.:2005)

80C51 Microcontrollers

Atmel Corporation 

Physical Layer

Frame Description

The UART used to transmit information has the following configuration:

• Character: 8-bit data

• Parity: none

• Stop: 2 bit

• Flow control: none

• Baud rate: autobaud is performed by the bootloader to compute the baud rate

chosen by the host.

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 length

1 byte

1 byte

Load Offset

2 bytes

Record Type

1 bytes

Data or Info

n byte

Checksum

1 byte

• 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.

8 A/T89C51AC2 UART Bootloader

4231C–CAN–03/05

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