Rainbow Electronics ATtiny43U - Manual (Page 144)

144
8048B–AVR–03/09
ATtiny43U
The XA1/XA0 pins determine the action executed when the CLKI pin is given a positive pulse.
The bit coding is shown in
Table 19-12 .
When pulsing WR or OE, the command loaded determines the action executed. The different
Commands are shown in
Table 19-13 .
19.6 Parallel Programming
19.6.1 Enter Programming Mode
The following algorithm puts the device in parallel programming mode:
1. Apply 4.5 - 5.5V between V
CC
and GND.
2. Set RESET to “0” and toggle CLKI at least six times.
3. Set the Prog_enable pins listed in Table 19-11 on page 143 to “0000” and wait at least
100 ns.
4. Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns after
+12V has been applied to RESET, will cause the device to fail entering programming
mode.
5. Wait at least 50 µs before sending a new command.
19.6.2 Considerations for Efficient Programming
The loaded command and address are retained in the device during programming. For efficient
programming, the following should be considered.
Table 19-12. XA1 and XA0 Coding
XA1 XA0 Action when CLKI 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 19-13. 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