Datasheet

177
8197C–AVR–05/11
ATtiny261A/461A/861A
The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a positive pulse.
The bit coding is shown in Table 18-14.
When pulsing WR
or OE, the command loaded determines the action executed. The different
Commands are shown in Table 18-15.
Table 18-13. Pin Values Used to Enter Programming Mode
Pin Symbol Value
PAGEL/BS1 Prog_enable[3] 0
XA1/BS2 Prog_enable[2] 0
XA0 Prog_enable[1] 0
WR Prog_enable[0] 0
Table 18-14. XA1 and XA0 Coding
XA1 XA0 Action when XTAL1 is Pulsed
0 0 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
Table 18-15. 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