Rainbow-electronics ATtiny43U Manual de usuario descargar pdf (Pagina 150)

150

8048B–AVR–03/09

ATtiny43U

1. A: Load Command “0010 0000”.

2. 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 Boot Lock bits by any

External Programming mode.

3. Give WR

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

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

19.6.12 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 145 for details on Command loading):

1. A: Load Command “0000 0100”.

2. 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).

3. 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).

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

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

5. 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).

6. Set OE

to “1”.

Figure 19-6. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read

19.6.13 Reading the Signature Bytes

The algorithm for reading the Signature bytes is as follows (refer to “Programming the Flash” on

page 145 for details on Command and Address loading):

1. A: Load Command “0000 1000”.

2. B: Load Address Low Byte (0x00 - 0x02).

3. Set OE

to “0”, and BS to “0”. The selected Signature byte can now be read at DATA.

4. Set OE

to “1”.

19.6.14 Reading the Calibration Byte

The algorithm for reading the Calibration byte is as follows (refer to “Programming the Flash” on

page 145 for details on Command and Address loading):

Lock Bits

BS2

Fuse High Byte

BS1

DATA

Fuse Low Byte

BS2

Extended Fuse Byte

1 2 ... 145 146 147 148 149 150 151 152 153 154 155 ... 181 182

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