AT89C51SND1_06 ATMEL [ATMEL Corporation], AT89C51SND1_06 Datasheet - Page 24

• Manufacturer Part Number: AT89C51SND1_06
• Description: USB Microcontrollers
• Manufacturer: ATMEL [ATMEL Corporation]

Erasing the Flash
Request From Host
Answers from
Bootloader
24
AT89C51SND1
The flow described below allows the user to erase the Flash memory.
Two modes of Flash erasing are possible:
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The Full Chip erase command erases the whole Flash (32 Kbytes) and sets some Configuration
Bytes at their default values:
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The Block erase command erases only a part of the Flash.
Four Blocks are defined in the AT89C51SND1:
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To start the erasing operation, the Host sends a DFU_DNLOAD request with a Write Command
in the data field (2 bytes).
The device has two possible answers to a DFU_GETSTATUS request:
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•
The full chip erase is always executed whatever the Software Security Byte value is.
Command Identifier
Id_write_command
Full chip erase
Block erase
BSB = FFh
SBV = FFh
SSB = FFh (NO_SECURITY)
block0 (from 0000h to 1FFFh)
block1 (from 2000h to 3FFFh)
block2 (from 4000h to 7FFFh)
block3 (from 8000h to FFFFh)
If the chip is protected from program access, a “err_WRITE” status is returned to the Host.
Otherwise, the device status is “OK“.
04h
data[0]
00h
data[1]
FFh
00h
20h
40h
80h
data[2]
data[3]
data[4]
Erase block0 (0K to 8K)
Erase block1 (8K to 16K)
Erase block2 (16K to 32K)
Erase block3 (32K to 64K)
Full Chip Erase (bits at FFh)
Description
4254C–MP3–03/06