ATMEGA8-16PC Atmel, ATMEGA8-16PC Datasheet - Page 208

• Manufacturer Part Number: ATMEGA8-16PC
• Description: IC AVR MCU 8K 16MHZ COM 28-DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8-16PC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA816PC

Self-Programming
the Flash
208
ATmega8(L)
Figure 103. Addressing the Flash during SPM
Notes:
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
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 the figure are listed in
2. PCPAGE and PCWORD are listed in
PROGRAM MEMORY
“Simple Assembly Code Example for a Boot Loader” on page 212
BIT
PROGRAM
COUNTER
15
PAGE
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
PCPAGE
ZPAGEMSB
PAGEMSB
PCWORD
Table 89 on page 218
WORD ADDRESS
WITHIN A PAGE
(1)
1
0
0
INSTRUCTION WORD
Table 84 on page 214
PAGE
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
for an assembly
2486Z–AVR–02/11