attiny25v ATMEL Corporation, attiny25v Datasheet - Page 150

• Manufacturer Part Number: attiny25v
• Description: Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

• Bit 4 – CTPB: Clear Temporary Page Buffer
If the CTPB bit is written while filling the temporary page buffer, the temporary page buffer will be
cleared and the data will be lost.
• Bit 3 – RFLB: Read Fuse and Lock Bits
An LPM instruction within three cycles after RFLB and SPMEN 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 destina-
tion register. See
“EEPROM Write Prevents Writing to SPMCSR” on page 147
for details.
• Bit 2 – PGWRT: Page Write
If this bit is written to one at the same time as SPMEN, 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 SPMEN, 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 0 – SPMEN: Store Program Memory Enable
This bit enables the SPM instruction for the next four clock cycles. If set to one together with
RSIG, CTPB, RFLB, PGWRT or PGERS, the following LPM/SPM instruction will have a special
meaning, as described elsewhere.
If only SPMEN is written, the following SPM instruction will store the value in R1:R0 in the tem-
porary page buffer addressed by the Z-pointer. The LSB of the Z-pointer is ignored. The SPMEN
bit will auto-clear upon completion of an SPM instruction, or if no SPM instruction is executed
within four clock cycles. During Page Erase and Page Write, the SPMEN bit remains high until
the operation is completed.
ATtiny25/45/85
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2586K–AVR–01/08