AVR Instruction Set Nomenclature: Status Register (SREG ...

SPM - Store Program Memory
Description:
SPM can be used to erase a page in the program memory, to write a page in the program memory (that is already erased),
and to set boot loader lock bits. In some devices, the program memory can be written one word at a time, in other devices
an entire page can be programmed simultaneously after first filling a temporary page buffer. In all cases, the program memory
must be erased one page at a time. When erasing the program memory, the Z register is used as page address. When
writing the program memory, the Z register is used as page or word address, and the R1:R0 register pair is used as data.
When setting the boot loader lock bits, the R1:R0 register pair is used as data. Refer to the device documentation for
detailed description of SPM usage. This instruction can address the first 64K bytes (32K words) of program memory.
Operation: Comment:
(i) (Z) ← $ffff Erase program memory page
(ii) (Z) ← R1:R0 Write program memory word
(iii) (Z) ← R1:R0 Write temporary page buffer
(iv) (Z) ← TEMP Write temporary page buffer to program memory
(v) BLBITS ← R1:R0 Set boot loader lock bits
Syntax: Operands: Program Counter:
(i)-(v) SPM None PC ← PC + 1
120
16-bit Opcode:
Status Register (SREG) and Boolean Formula:
Example:
1001 0101 1110 1000
I T H S V N Z C
- - - - - - - -
; This example shows SPM write of one word for devices with word write
ldi r31, $F0 ; Load Z high byte
clr r30 ; Clear Z low byte
ldi r16, $CF ; Load data to store
mov r1, r16
ldi r16, $FF
mov r0, r16
ldi r16,$03 ; Enable SPM, erase page
out SPMCR, r16 ;
spm ; Erase page starting at $F000
ldi r16,$01 ; Enable SPM, store to program memory
out SPMCR, r16 ;
spm ; Execute SPM, store R1:R0 to program memory location $F000
Words: 1 (2 bytes)
Cycles: depends on the operation
Instruction Set