Rainbow Electronics ATtiny861_V - Manual (Page 173)

173
2588B–AVR–11/06
ATtiny261/461/861
22.7 Parallel Programming
22.7.1 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 XTAL1 at least six times.
3. Set the Prog_enable pins listed in Table 22-10 on page 172 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.
22.7.2 Considerations for Efficient Programming
The loaded command and address are retained in the device during programming. For efficient
programming, the following should be considered.
• The command needs only be loaded once when writing or reading multiple memory locations.
• Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the
EESAVE Fuse is programmed) and Flash after a Chip Erase.
• Address high byte needs only be loaded before programming or reading a new 256 word
window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes
reading.
Table 22-11. 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 22-12. 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