ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 273

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

26.2.4
26.2.5
9223B–AVR–09/11
Programming Time for Flash when Using SPM
Simple Assembly Code Example for a Boot Loader
The calibrated RC Oscillator is used to time Flash accesses.
gramming time for Flash accesses from the CPU.
Table 26-1.
Note that the RWWSB bit will always be read as zero in Atmel
it is recommended to check this bit as shown in the code example, to ensure compatibility with
devices supporting Read-While-Write.
Flash write (Page Erase, Page Write, and
write Lock bits by SPM)
Note:
.equ PAGESIZEB = PAGESIZE*2
.org SMALLBOOTSTART
Write_page:
Wrloop:
Atmel ATmega48PA/88PA/168PA [Preliminary]
;-the routine writes one page of data from RAM to Flash
; the first data location in RAM is pointed to by the Y pointer
; the first data location in Flash is pointed to by the Z-pointer
;-error handling is not included
;-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
rcallDo_spm
; re-enable the RWW section
ldi
rcallDo_spm
; transfer data from RAM to Flash page buffer
ldi
ldi
ld
ld
ldi
rcallDo_spm
adiw ZH:ZL, 2
sbiw loophi:looplo, 2
brne Wrloop
; execute Page Write
1. Minimum and maximum programming time is per individual operation.
spmcrval, (1<<PGERS) | (1<<SELFPRGEN)
spmcrval, (1<<RWWSRE) | (1<<SELFPRGEN)
looplo, low(PAGESIZEB)
loophi, high(PAGESIZEB)
r0, Y+
r1, Y+
spmcrval, (1<<SELFPRGEN)
SPM Programming Time
Symbol
(1)
;PAGESIZEB is page size in BYTES, not words
Min. Programming Time
;init loop variable
;not required for PAGESIZEB<=256
;use subi for PAGESIZEB<=256
3.7ms
Table 27-6
®
ATmega48PA. Nevertheless,
Max Programming Time
shows the typical pro-
4.5ms
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