AT90PWM81-16SN Atmel, AT90PWM81-16SN Datasheet - Page 240

• Manufacturer Part Number: AT90PWM81-16SN
• Description: IC MCU AVR 8K FLASH ISP 20SOIC
• Manufacturer: Atmel
• Series: AVR® 90PWM Lightingr

Specifications of AT90PWM81-16SN

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI
• Peripherals: Brown-out Detect/Reset, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 20-SOIC (7.5mm Width)
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: SPI
• Maximum Clock Frequency: 16 MHz
• Number Of Timers: 1
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• On-chip Dac: 10 bit, 1 Channel
• Height: 2.35 mm
• Length: 13 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Width: 7.6 mm
• For Use With: ATSTK600-SOIC - STK600 SOCKET/ADAPTER FOR SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

20.7
240
Self-Programming the Flash
AT90PWM81
Figure 20-3.
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 buffer 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 tem-
porary 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 alternative 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
page 244
• 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
for an assembly code example.
PROGRAM MEMORY
BIT
Addressing the Flash During SPM
PAGE
PROGRAM
COUNTER
15
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
PCPAGE
Figure 20-3
ZPAGEMSB
PAGEMSB
PCWORD
“Simple Assembly Code Example for a Boot Loader” on
(1)
are listed in
WORD ADDRESS
WITHIN A PAGE
1
0
0
INSTRUCTION WORD
Table 20-9 on page
PAGE
247.
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
7734P–AVR–08/10