ATtiny44 datasheet(156/236 Pages) ATMEL

156 / 236 page

156

8006H–AVR–10/09

ATtiny24/44/84

To read the Fuse High Byte (FHB), simply replace the address in the Z-pointer with 0x0003 and

repeat the procedure above. If successful, the contents of the destination register are as follows.

Refer to Table 19-4 on page 160 for detailed description and mapping of the Fuse High Byte.

To read the Fuse Extended Byte (FEB), replace the address in the Z-pointer with 0x0002 and

repeat the previous procedure. If successful, the contents of the destination register are as

follows.

Refer to Table 19-3 on page 160 for detailed description and mapping of the Fuse Extended

Byte.

18.6.3

Reading Device Signature Imprint Table from Firmware

To read the contents of the device signature imprint table, follow the below procedure:

Load the Z-pointer with the table index.

Set RSIG and SPMEN bits in SPMCSR.

Issue an LPM instruction within three clock cycles.

Wait three clock cycles for SPMEN bits to be cleared.

Read table data from the LPM destination register.

The RSIG and SPMEN bits will auto-clear after three CPU cycles. When RSIG and SPMEN are

cleared, LPM will work as described in the “AVR Instruction Set” description.

See program example below.

Note:

See “Code Examples” on page 6.

Bit

543

FHB7

FHB6

FHB5

FHB4

FHB3

FHB2

FHB1

FHB0

Bit

543

FEB7

FEB6

FEB5

FEB4

FEB3

FEB2

FEB1

FEB0

Assembly Code Example

DSIT_read:

; Uses Z-pointer as table index

ldi

ZH, 0

ldi

ZL, 1

; Preload SPMCSR bits into R16, then write to SPMCSR

ldi

r16, (1<<RSIG)|(1<<SPMEN)

out

SPMCSR, r16

; Issue LPM. Table data will be returned into r17

lpm

r17, Z

ret

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