ATMEGA16U2-16AU Atmel, ATMEGA16U2-16AU Datasheet - Page 233

• Manufacturer Part Number: ATMEGA16U2-16AU
• Description: 8-bit Microcontrollers - MCU 16K Flash
• Manufacturer: Atmel

Specifications of ATMEGA16U2-16AU

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: AVR
• Data Bus Width: 8 bit
• Program Memory Size: 16 KB
• Data Ram Size: 1.25 KB
• Data Rom Size: 512 B
• Program Memory Type: Flash
• Factory Pack Quantity: 1250

23.8
7799D–AVR–11/10
Self-Programming the Flash
Figure 23-4. Addressing the Flash During SPM
Note:
The program memory is updated in a page by page fashion. Before programming a page with
the data stored in the temporary page buffer, the page must be erased. The temporary page buf-
fer is filled one word at a time using SPM and the buffer can be filled either before the Page
Erase command or between a Page Erase and a Page Write operation:
Alternative 1, fill the buffer before a Page Erase
Alternative 2, fill the buffer after Page Erase
If only a part of the page needs to be changed, the rest of the page must be stored (for example
in the temporary page buffer) before the erase, and then be rewritten. When using alternative 1,
the Boot Loader provides an effective Read-Modify-Write feature which allows the user software
to first read the page, do the necessary changes, and then write back the modified data. If alter-
native 2 is used, it is not possible to read the old data while loading since the page is already
erased. The temporary page buffer can be accessed in a random sequence. It is essential that
the page address used in both the Page Erase and Page Write operation is addressing the
same page. See
assembly code example.
• Fill temporary page buffer
• Perform a Page Erase
• Perform a Page Write
• Perform a Page Erase
• Fill temporary page buffer
• Perform a Page Write
Z - REGISTER
1. The different variables used in
PROGRAM MEMORY
BIT
PAGE
PROGRAM
COUNTER
15
“Simple Assembly Code Example for a Boot Loader” on page 237
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
PCPAGE
Figure 23-4
ZPAGEMSB
PAGEMSB
PCWORD
WORD ADDRESS
WITHIN A PAGE
(1)
are listed in
ATmega8U2/16U2/32U2
1
0
0
INSTRUCTION WORD
PAGE
Table 23-10 on page
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
239.
for an
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