ATmega88 datasheet(258/340 Pages) ATMEL

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258

7530H–AVR–02/09

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

destination register. See “Reading the Fuse and Lock Bits from Software” on page 259 for

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

SPMIE

RWWSB

–

RWWSRE

BLBSET

PGWRT

PGERS

SELFPRGEN

SPMCSR

Read/Write

R/W

Initial Value

ATmega88 Datasheet(PDF) 258 Page - ATMEL Corporation

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