AT89LP428-20MU ATMEL [ATMEL Corporation], AT89LP428-20MU Datasheet - Page 117

• Manufacturer Part Number: AT89LP428-20MU
• Description: 8-bit Microcontroller with 4K/8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

23.3
3654A–MICRO–8/09
Command Format
Table 23-2.
Figure 23-2. AT89LP428/828 Memory Organization
Programming commands consist of an opcode byte, two address bytes, and zero or more data
bytes. In addition, all command packets must start with a two-byte preamble of AAH and 55H.
The preamble increases the noise immunity of the programming interface by making it more dif-
ficult to issue unintentional commands.
a command sequence.
A sample command packet is shown in
frame. SS must be brought low before the first byte in a command is sent and brought back high
after the final byte in the command has been sent. The command is not complete until SS
returns high. Command bytes are issued serially on MOSI. Data output bytes are received seri-
ally on MISO. Packets of variable length are supported by returning SS high when the final
required byte has been transmitted. In some cases command bytes have a don’t care value.
Don’t care bytes in the middle of a packet must be transmitted. Don’t care bytes at the end of a
packet may be ignored.
Page-oriented instructions always include a full 16-bit address. The higher order bits select the
page and the lower order bits select the byte within that page. The AT89LP428/828 allocates
6 bits for byte address and 7 bits for page address. The page to be accessed is always fixed by
the page address as transmitted. The byte address specifies the starting address for the first
AT89LP428
AT89LP828
Device #
Data Memory Size
1024 bytes
Data Size
512 bytes
Atmel Signature Array
User Signature Array
Code Memory
Data Memory
User Fuse Row
Figure 23-3 on page 118
Figure 23-4 on page
Page Size
64 bytes
64 bytes
00
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# Pages
118. The SS pin defines the packet
16
8
shows a simplified flow chart of
3F
AT89LP428/828
05FF
0200
1FFF
0000
Address Range
0200H - 03FFH
0200H - 05FFH
117