ATtiny48 datasheet(189/266 Pages) ATMEL

189 / 266 page

189

8008C–AVR–03/09

ATtiny48/88

When pulsing WR or OE, the command loaded determines the action executed. The different

Commands are shown in Table 20-12.

20.7

Parallel Programming

20.7.1

Enter Programming Mode

The following algorithm puts the device in Parallel (High-voltage) Programming mode:

Set Prog_enable pins listed in Table 20-10 on page 188 to “0000”, RESET pin to 0V

and V

CC to 0V.

Apply 4.5 – 5.5V between V

CC and GND.

Ensure that V

CC reaches at least 1.8V within the next 20 µs.

Wait 20 – 60 µs, and apply 11.5 – 12.5V to RESET.

Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has

been applied to ensure the Prog_enable Signature has been latched.

Wait at least 300 µs before giving any parallel programming commands.

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.

Set Prog_enable pins listed in Table 20-10 on page 188 to “0000”, RESET pin to 0V

and V

CC to 0V.

Apply 4.5 – 5.5V between V

CC and GND.

Monitor V

CC, and as soon as VCC reaches 0.9 – 1.1V, apply 11.5 – 12.5V to RESET.

Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has

been applied to ensure the Prog_enable Signature has been latched.

Wait until V

CC actually reaches 4.5 -5.5V before giving any parallel programming

commands.

Exit Programming mode by power the device down or by bringing RESET pin to 0V.

Table 20-12. 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

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