Datasheet

183
8246A–AVR–11/09
ATtiny2313A/4313
20.6 Parallel Programming
20.6.1 Enter Programming Mode
The following algorithm puts the device in Parallel programming mode:
1. Set Prog_enable pins listed in Table 20-10 on page 183 to “0000”, RESET pin and V
CC
to 0V.
2. Apply 4.5 - 5.5V between V
CC
and GND.
3. Ensure that V
CC
reaches at least 1.8V within the next 20 µs.
Table 20-10. Pin Values Used to Enter Programming Mode
Pin Symbol Value
XA1 Prog_enable[3] 0
XA0 Prog_enable[2] 0
BS1 Prog_enable[1] 0
WR Prog_enable[0] 0
Table 20-11. XA1 and XA0 Coding
XA1 XA0 Action when XTAL1 is Pulsed
00
Load Flash or EEPROM Address (High or low address byte
determined by BS1).
0 1 Load Data (High or Low data byte for Flash determined by BS1).
1 0 Load Command
1 1 No Action, Idle
When pulsing WR or OE, the command loaded determines the action executed. The different
Commands are shown in Table 20-12.
Table 20-12. Command Byte Bit Coding
Command Byte Command Executed
1000 0000 Chip Erase
0100 0000 Write Fuse bits
0010 0000 Write Lock bits
0001 0000 Write Flash
0001 0001 Write EEPROM
0000 1000 Read Signature Bytes and Calibration byte
0000 0100 Read Fuse and Lock bits
0000 0010 Read Flash
0000 0011 Read EEPROM