ATMEGA328P-20PU Atmel, ATMEGA328P-20PU Datasheet - Page 284

• Manufacturer Part Number: ATMEGA328P-20PU
• Manufacturer: Atmel

Specifications of ATMEGA328P-20PU

• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Interface Type: SPI/TWI/USART
• Program Memory Type: Flash
• Program Memory Size: 32KB
• Total Internal Ram Size: 2KB
• # I/os (max): 23
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 6-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 28
• Package Type: PDIP
• Lead Free Status / Rohs Status: Compliant

8025K–AVR–10/09
.equ PAGESIZEB = PAGESIZE*2
.org SMALLBOOTSTART
Write_page:
Wrloop:
Rdloop:
Return:
;-the routine must be placed inside the Boot space
; (at least the Do_spm sub routine). Only code inside NRWW section can
; be read during Self-Programming (Page Erase and Page Write).
;-registers used: r0, r1, temp1 (r16), temp2 (r17), looplo (r24),
; loophi (r25), spmcrval (r20)
; storing and restoring of registers is not included in the routine
; register usage can be optimized at the expense of code size
;-It is assumed that either the interrupt table is moved to the Boot
; loader section or that the interrupts are disabled.
; Page Erase
ldi
call Do_spm
; re-enable the RWW section
ldi
call Do_spm
; transfer data from RAM to Flash page buffer
ldi
ldi
ld
ld
ldi
call Do_spm
adiw ZH:ZL, 2
sbiw loophi:looplo, 2
brne Wrloop
; execute Page Write
subi ZL, low(PAGESIZEB)
sbci ZH, high(PAGESIZEB)
ldi
call Do_spm
; re-enable the RWW section
ldi
call Do_spm
; read back and check, optional
ldi
ldi
subi YL, low(PAGESIZEB)
sbci YH, high(PAGESIZEB)
lpm
ld
cpse r0, r1
jmp
sbiw loophi:looplo, 1
brne Rdloop
; return to RWW section
; verify that RWW section is safe to read
in
spmcrval, (1<<PGERS) | (1<<SELFPRGEN)
spmcrval, (1<<RWWSRE) | (1<<SELFPRGEN)
looplo, low(PAGESIZEB)
loophi, high(PAGESIZEB)
r0, Y+
r1, Y+
spmcrval, (1<<SELFPRGEN)
spmcrval, (1<<PGWRT) | (1<<SELFPRGEN)
spmcrval, (1<<RWWSRE) | (1<<SELFPRGEN)
looplo, low(PAGESIZEB)
loophi, high(PAGESIZEB)
r0, Z+
r1, Y+
Error
temp1, SPMCSR
;PAGESIZEB is page size in BYTES, not words
;init loop variable
;not required for PAGESIZEB<=256
;use subi for PAGESIZEB<=256
;restore pointer
;not required for PAGESIZEB<=256
;init loop variable
;not required for PAGESIZEB<=256
;restore pointer
;use subi for PAGESIZEB<=256
ATmega48P/88P/168P
284