Rainbow Electronics AT89C5132 - Manual (Page 22)

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AT89C5132
4256A–USB–06/03
Erasing the Flash The flow described below allows the user to erase the Flash memory.
Two modes of Flash erasing are possible:
•
Full chip erase
• Block erase
The Full Chip erase command erases the whole Flash (32 Kbytes) and sets some Con-
figuration Bytes at their default values:
•
BSB = FFh
• SBV = FFh
• SSB = FFh (NO_SECURITY)
The Block erase command erases only a part of the Flash.
Four Blocks are defined in the AT89C5132:
•
block0 (from 0000h to 1FFFh)
• block1 (from 2000h to 3FFFh)
• block2 (from 4000h to 7FFFh)
• block3 (from 8000h to FFFFh)
Request From Host To start the erasing operation, the Host sends a DFU_DNLOAD request with a Write
Command in the data field (2 bytes).
Answers from Bootloader The device has two possible answers to a DFU_GETSTATUS request:
•
If the chip is protected from program access, a “err_WRITE” status is returned to the
Host.
• Otherwise, the device status is “OK“.
The full chip erase is always executed whatever the Software Security Byte value is.
Command
Identifier data[0] data[1] data[2] data[3] data[4] Description
Id_write_command
04h
00h
00h Erase block0 (0K to 8K)
20h Erase block1 (8K to 16K)
40h Erase block2 (16K to 32K)
80h Erase block3 (32K to 64K)
FFh
Full chip erase (bits at
FFh)