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7530J–AVR–03/12
Atmel ATmega48/88/168 Automotive
23.1.1
Store Program Memory Control and Status Register – SPMCSR
The Store Program Memory Control and Status Register contains the control bits needed to con-
trol the Program memory operations.
Bit 7 – SPMIE: SPM Interrupt Enable
When the SPMIE bit is written to one, and the I-bit in the Status Register is set (one), the SPM
ready interrupt will be enabled. The SPM ready Interrupt will be executed as long as the SELF-
PRGEN bit in the SPMCSR Register is cleared.
Bit 6 – RWWSB: Read-While-Write Section Busy
This bit is for compatibility with devices supporting Read-While-Write. It will always read as zero
in ATmega48.
Bit 5 – Res: Reserved Bit
This bit is a reserved bit in the ATmega48/88/168 and will always read as zero.
Bit 4 – RWWSRE: Read-While-Write Section Read Enable
The functionality of this bit in ATmega48 is a subset of the functionality in ATmega88/168. If the
RWWSRE bit is written while filling the temporary page buffer, the temporary page buffer will be
cleared and the data will be lost.
Bit 3 – BLBSET: Boot Lock Bit Set
The functionality of this bit in ATmega48 is a subset of the functionality in ATmega88/168. An
LPM instruction within three cycles after BLBSET and SELFPRGEN are set in the SPMCSR
Register, will read either the Lock bits or the Fuse bits (depending on Z0 in the Z-pointer) into the
details.
Bit 2 – PGWRT: Page Write
If this bit is written to one at the same time as SELFPRGEN, the next SPM instruction within four
clock cycles executes Page Write, with the data stored in the temporary buffer. The page
address is taken from the high part of the Z-pointer. The data in R1 and R0 are ignored. The
PGWRT bit will auto-clear upon completion of a Page Write, or if no SPM instruction is executed
within four clock cycles. The CPU is halted during the entire Page Write operation.
Bit 1 – PGERS: Page Erase
If this bit is written to one at the same time as SELFPRGEN, the next SPM instruction within four
clock cycles executes Page Erase. The page address is taken from the high part of the
Z-pointer. The data in R1 and R0 are ignored. The PGERS bit will auto-clear upon completion of
a Page Erase, or if no SPM instruction is executed within four clock cycles. The CPU is halted
during the entire Page Write operation.
Bit
7
6
5
4
3
2
1
0
SPMIE
RWWSB
–
RWWSRE
BLBSET
PGWRT
PGERS
SELFPRGEN
SPMCSR
Read/Write
R/W
R
R/W
Initial Value
0