ATtiny48 datasheet(195/266 Pages) ATMEL

195 / 266 page

195

8008C–AVR–03/09

ATtiny48/88

Figure 20-5. Programming the FUSES Waveforms

20.7.11

Programming the Lock Bits

The algorithm for programming the Lock bits is as follows (refer to “Programming the Flash” on

page 190 for details on Command and Data loading):

A: Load Command “0010 0000”.

C: Load Data Low Byte. Bit n = “0” programs the Lock bit. If LB mode 3 is programmed

(LB1 and LB2 is programmed), it is not possible to program the Lock Bits by any Exter-

nal Programming mode.

Give WR a negative pulse and wait for RDY/BSY to go high.

The Lock bits can only be cleared by executing Chip Erase.

20.7.12

Reading the Fuse and Lock Bits

The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming the Flash”

on page 190 for details on Command loading):

A: Load Command “0000 0100”.

Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can now be

read at DATA (“0” means programmed).

Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can now be

read at DATA (“0” means programmed).

Set OE to “0”, BS2 to “1”, and BS1 to “0”. The status of the Fuse Extended bits can now

be read at DATA (“0” means programmed).

Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be read at

DATA (“0” means programmed).

Set OE to “1”.

RDY/BSY

RESET +12V

PAGEL

0x40

DATA

XA1

XA0

BS1

CLKI

0x40

DATA

Write Fuse Low byte

Write Fuse high byte

0x40

DATA

Write Extended Fuse byte

BS2

ATtiny48 Datasheet(PDF) 195 Page - ATMEL Corporation

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