T83C51SND1-ROTIL datasheet(24/60 Pages) ATMEL

24 / 60 page

T8xC51SND1

Rev. D – 15-Nov-01

8.5 Serial Boot Loader

8.6.1 Configuration

The serial boot loader is based on the internal UART and needs only 3 pins: the TXD

and RXD pins of the UART and the VSS pin.

The data transmission format on the serial link must be set to 8 data bits with 1 stop bit.

The baud rate is automatically recognized during the synchronization phase.

8.7.2 Synchronization Phase

Before any data may be sent to the boot loader, a synchronization must be achieved

with the host so that both side converse at the same baud rate. This is done by sending

the “U” character (ASCII 35h) to the boot loader. The boot loader acknowledges the syn-

chronization by responding the same “U” character.

At this time, the boot loader is able to receive data, then all data received are echoed to

the host.

8.8.3 Command Protocol

Definition

The protocol is based on the INTEL‚ HEX type records. These records are composed of

seven fields of ASCII characters as detailed in Table 34. All fields except SOR (Start Of

Record) end EOR (End Of Record) are ASCII coded hexadecimal values. The SOR field

is always a “:” character. The EOR field is always a Carriage Return (ASCII 13h) fol-

lowed by a Line Feed (ASCII 0Ah). The SIZE field is the size of the DATA field. The

ADDRESS field is the address where to store data contained in the DATA field. The

TYPE field is the record type detailed in Table 35. The DATA field contains the data and

must never exceed 128 data bytes (256 ASCII characters). The CKSUM field is the

checksum computed on the SIZE, ADDRESS, TYPE, DATA fields.

Table 34. Hex Record Format

Error Handling

All received records that present a checksum error, a data length greater than 128 bytes

or a bad type record are immediately acknowledged to the host by sending a “X” charac-

ter followed by a CRLF sequence.

Command description

Table 35. Hex Record Commands

SOR

SIZE

ADDRESS

TYPE

DATA

CKSUM

EOR

:NN

AAAA

DD…DD

CR LF

TYPE

SIZE

ADDRESS

Description

00h

01h to 80h

0000h to

FFFFh

Program Data

Program the data in the DATA field at the address contained in the

ADDRESS field.

Return

“.”

Done.

“P”

Not done. Part protected (secured by level 1 or 2).

01h

00h

0000h

End of File

No operation.

Return

“.”

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