ATMEGA8A-PU Atmel, ATMEGA8A-PU Datasheet - Page 218

MCU AVR 8K FLASH 16MHZ 28-PDIP

ATMEGA8A-PU

Manufacturer Part Number
ATMEGA8A-PU
Description
MCU AVR 8K FLASH 16MHZ 28-PDIP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA8A-PU

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)
2.7 V ~ 5.5 V
Data Converters
A/D 6x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
28-DIP (0.300", 7.62mm)
Processor Series
ATMEGA8x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
1 KB
Interface Type
SPI, TWI, USART
Maximum Clock Frequency
16 MHz
Number Of Programmable I/os
23
Number Of Timers
3
Maximum Operating Temperature
+ 85 C
Mounting Style
Through Hole
3rd Party Development Tools
EWAVR, EWAVR-BL
Development Tools By Supplier
ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
Minimum Operating Temperature
- 40 C
On-chip Adc
10 bit, 6 Channel
Package
28PDIP
Device Core
AVR
Family Name
ATmega
Maximum Speed
16 MHz
Operating Supply Voltage
3.3|5 V
Controller Family/series
AVR MEGA
No. Of I/o's
23
Eeprom Memory Size
512Byte
Ram Memory Size
1KB
Cpu Speed
16MHz
Rohs Compliant
Yes
For Use With
ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA8A-PU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
23.8
23.8.1
23.8.2
8159D–AVR–02/11
Self-Programming the Flash
Performing Page Erase by SPM
Filling the Temporary Buffer (Page Loading)
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.
To execute page erase, set up the address in the Z-pointer, write “X0000011” to SPMCR and
execute SPM within four clock cycles after writing SPMCR. The data in R1 and R0 is ignored.
The page address must be written to PCPAGE in the Z-register. Other bits in the Z-pointer will
be ignored during this operation.
Note:
To write an instruction word, set up the address in the Z-pointer and data in R1:R0, write
“00000001” to SPMCR and execute SPM within four clock cycles after writing SPMCR. The con-
tent of PCWORD in the Z-register is used to address the data in the temporary page buffer. The
temporary buffer will auto-erase after a page write operation or by writing the RWWSRE bit in
SPMCR. It is also erased after a System Reset. Note that it is not possible to write more than
one time to each address without erasing the temporary buffer.
Note:
• Fill temporary page buffer.
• Perform a page erase.
• Perform a page write.
• Perform a page erase.
• Fill temporary page buffer.
• Perform a page write.
• Page Erase to the RWW section: The NRWW section can be read during the page erase.
• Page Erase to the NRWW section: The CPU is halted during the operation.
1. The different variables used in the figure are listed in
2. PCPAGE and PCWORD are listed in
If an interrupt occurs in the timed seqence the four cycle access cannot be guaranteed. In order to
ensure atomic operation disable interrupts before writing to SPMCSR.
If the EEPROM is written in the middle of an SPM page Load operation, all data loaded will be
lost.
“Simple Assembly Code Example for a Boot Loader” on page 221
Table 24-5 on page
Table 23-8 on page
229.
ATmega8A
223.
for an assembly
218

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