Datasheet

234
ATtiny828 [DATASHEET]
8371A–AVR–08/12
Table 98. XA1 and XA0 Coding
When pulsing WR or OE, the command loaded determines the action executed. The different command options are
shown in Table 99.
Table 99. Command Byte Bit Coding
23.2.1 Enter Programming Mode
The following algorithm puts the device in Parallel (High-voltage) Programming mode:
1. Set Prog_enable pins (see Table 97 on page 233) to “0000”, RESET
pin to 0V and V
CC
to 0V.
2. Apply 4.5 – 5.5V between V
CC
and GND. Ensure that V
CC
reaches at least 1.7V within the next 20 µs.
3. Wait 20 – 60 µs, and apply 11.5 – 12.5V to RESET
.
4. Keep the Prog_enable pins unchanged for at least 10µs after the high voltage has been applied to ensure
Prog_enable signature has been latched.
5. Wait at least 300 µs before giving any parallel programming commands.
6. Exit programming mode by powering 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 alternative algorithm can be used:
1. Set Prog_enable pins (Table 97 on page 233) to “0000”, RESET
pin to 0V and V
CC
to 0V.
2. Apply 4.5 – 5.5V between V
CC
and GND.
3. Monitor V
CC
, and as soon as V
CC
reaches 0.9 – 1.1V, apply 11.5 – 12.5V to RESET.
4. Keep the Prog_enable pins unchanged for at least 10µs after the high voltage has been applied to ensure
Prog_enable signature has been latched.
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
Command Byte Command
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