at89c51snd1 ATMEL Corporation, at89c51snd1 Datasheet - Page 12

• Manufacturer Part Number: at89c51snd1
• Description: Mp3 Microcontrollers
• Manufacturer: ATMEL Corporation

Reading the Flash Data
Requests from Host
Answers from Bootloader
Flow Description
Figure 7. Blank Check Command
12
COMMAND FINISHED
AT89C51SND1 UART Bootloader
Wait Address not
Send Blank Check Command
Erased
OR
Host
OR
COMMAND ABORTED
Wait Checksum Error
COMMAND FINISHED
Wait COMMAND_OK
The flow described in Figure 7 allows the user to read data in the Flash memory. A blank
check command is possible with this flow.
The device splits into blocks of 16 bytes the data to transfer to the Host if the number of
data to display is greater than 16 data bytes.
Note:
The bootloader answers to a read Flash data memory command:
•
•
•
The bootloader answers to blank check command:
•
•
•
•
Command Name
Blank check on
Read Flash
"Address = data " & "CR" & "LF"
up to 16 data by line.
"X" & "CR" & "LF" if the checksum is wrong
"L" & "CR" & "LF" if the Security is set
"." & "CR" & "LF" when the blank check is OK
"First Address wrong" "CR" & "LF" when the blank check is fail
"X" & "CR" & "LF" if the checksum is wrong
"P" & "CR" & "LF" if the Security is set
Flash
The field “Load offset” is not used.
Blank Check Command
Address & CR & LF
“X” & CR & LF
“.” & CR & LF
Record
Type
04h
Offset
Load
x
Record
Length
05h
Send COMMAND_OK
Send Checksum Error
Data[0]
Start Address
Wait Blank Check Command
Bootloader
Data[1]
Send First Address
Not Erased
Checksum Error
Flash Blank
Data[2]
End Address
Data[3]
4241B–MP3–07/04
Data[4]
00h
01h