attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 214

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

20.2.7
214
ATtiny167
Simple Assembly Code Example for a Boot Loader
Note that the RWWSB bit will always be read as zero in ATtiny167. Nevertheless, it is
recommended to check this bit as shown in the code example, to ensure compatibility with
devices supporting Read-While-Write.
.equ PAGESIZEB = PAGESIZE*2
.org SMALLBOOTSTART
Write_page:
Wrloop:
Rdloop:
;- The routine writes one page of data from RAM to Flash
;
;
;- Error handling is not included
;- Registers used: r0, r1, temp1 (r16), temp2 (r17), looplo (r24),
;
; - Storing and restoring of registers is not included in the routine
;
; Page Erase
ldi
rcall Do_spm
; Clear temporary page buffer
ldi
rcall Do_spm
; Transfer data from RAM to Flash temporary page buffer
ldi
ldi
ld
ld
ldi
rcall Do_spm
adiw
sbiw
brne
; Execute Page Write
subi
sbci
ldi
rcall Do_spm
; Clear temporary page buffer
ldi
rcall Do_spm
; Read back and check, optional
ldi
ldi
subi
sbci
lpm
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
register usage can be optimized at the expense of code size
spmcsrval, (1<<PGERS) | (1<<SELFPGEN)
spmcsrval, (1<<CPTB) | (1<<SELFPGEN)
looplo, low(PAGESIZEB)
loophi, high(PAGESIZEB)
r0, Y+
r1, Y+
spmcsrval, (1<<SELFPGEN)
ZH:ZL, 2
loophi:looplo, 2
Wrloop
ZL, low(PAGESIZEB)
ZH, high(PAGESIZEB)
spmcsrval, (1<<PGWRT) | (1<<SELFPGEN)
spmcsrval, (1<<CPTB) | (1<<SELFPGEN)
looplo, low(PAGESIZEB)
loophi, high(PAGESIZEB)
YL, low(PAGESIZEB)
YH, high(PAGESIZEB)
r0, Z+
loophi (r25), spmcsrval (r20)
; AGESIZEB is page size in BYTES, not words
; use subi for PAGESIZEB<=256
; restore pointer
; not required for PAGESIZEB<=256
; init loop variable
; not required for PAGESIZEB<=256
; restore pointer
; init loop variable
; not required for PAGESIZEB<=256
7728A–AUTO–07/08