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193
8008H–AVR–04/11
ATtiny48/88
When pulsing WR or OE, the command loaded determines the action executed. The different
21.2.1
Enter Programming Mode
The following algorithm puts the device in Parallel (High-voltage) Programming mode:
1.
V
CC to 0V.
2.
Apply 4.5 – 5.5V between V
CC and GND. Ensure that VCC reaches at least 1.8V within
the next 20 s.
3.
Wait 20 – 60 s, and apply 11.5 – 12.5V to RESET.
4.
Keep the Prog_enable pins unchanged for at least 10s after the High-voltage has
been applied to ensure the Prog_enable Signature has been latched.
5.
Wait at least 300 s before giving any parallel programming commands.
6.
Exit Programming mode by power the device down or by bringing RESET pin to 0V.
If the rise time of the V
CC is unable to fulfill the requirements listed above, the following alterna-
tive algorithm can be used.
1.
V
CC to 0V.
2.
Apply 4.5 – 5.5V between V
CC and GND.
3.
Monitor V
CC, and as soon as VCC reaches 0.9 – 1.1V, apply 11.5 – 12.5V to RESET.
4.
Keep the Prog_enable pins unchanged for at least 10s after the High-voltage has
been applied to ensure the Prog_enable Signature has been latched.
5.
Wait until V
CC actually reaches 4.5 -5.5V before giving any parallel programming
commands.
6.
Exit Programming mode by power the device down or by bringing RESET pin to 0V.
21.2.2
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 21-6.
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