Datasheet

193
8246B–AVR–09/11
ATtiny2313A/4313
Figure 21-6. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
21.2.13 Reading Signature Bytes
The algorithm for reading the signature bytes is as follows (see “Programming the Flash” on
page 187 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 BS1 to “0”. The selected Signature byte can now be read at DATA.
4. Set OE
to “1”.
21.2.14 Reading the Calibration Byte
The algorithm for reading the calibration byte is as follows (see “Programming the Flash” on
page 187 for details on command and address loading):
1. A: Load Command “0000 1000”.
2. B: Load Address Low Byte, 0x00.
3. Set OE
to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA.
4. Set OE
to “1”.
21.3 Serial Programming
Flash and EEPROM memory arrays can both be programmed using the serial SPI bus while
RESET
is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (out-
put). After RESET
is set low, the Programming Enable instruction needs to be executed before
program/erase operations can be executed.
Serial programming signals and connections are illustrated in Figure 21-7, below. The pin map-
ping is listed in Table 21-7 on page 195.
Lock Bits
0
1
BS2
Fuse High Byte
0
1
BS1
DATA
Fuse Low Byte
0
1
BS2
Extended Fuse Byte