attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 100

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

Store Program Memory
Control and Status Register –
SPMCSR
100
ATtiny13
The Store Program Memory Control and Status Register contains the control bits
needed to control the Program memory operations.
• Bits 7..5 – Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and always read as zero.
• 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 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 destination register. See “EEPROM Write Prevents Writing to
SPMCSR” on page 101 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 0 – SELFPRGEN: Self Programming Enable
This bit enables the SPM instruction for the next four clock cycles. If written to one
together with either CTPB, RFLB, PGWRT, or PGERS, the following SPM instruction
will have a special meaning, see description above. If only SELFPRGEN is written, the
following SPM instruction will store the value in R1:R0 in the temporary page buffer
addressed by the Z-pointer. The LSB of the Z-pointer is ignored. The SELFPRGEN bit
will auto-clear upon completion of an SPM instruction, or if no SPM instruction is exe-
cuted within four clock cycles. During Page Erase and Page Write, the SELFPRGEN bit
remains high until the operation is completed.
Writing any other combination than “10001”, “01001”, “00101”, “00011” or “00001” in the
lower five bits will have no effect.
Bit
Read/Write
Initial Value
R
7
–
0
R
6
–
0
R
5
–
0
CTPB
R/W
4
0
RFLB
R/W
3
0
PGWRT
R/W
2
0
PGERS
R/W
1
0
SELFPRGEN
R/W
0
0
2535G–AVR–01/07
SPMCSR