Rainbow Electronics ATmega3290P_V - Manual (Page 287)

287
ATmega329/3290/649/6490
2552H–AVR–11/06
Parallel Programming
Enter Programming Mode The following algorithm puts the device in Parallel (High-voltage) Programming mode:
1. Set Prog_enable pins listed in Table 129 on page 285 to “0000”, RESET pin and
V
CC
to 0V.
2. Apply 4.5 - 5.5V between V
CC
and GND.
3. Ensure that V
CC
reaches at least 1.8V within the next 20 µs.
4. Wait 20 - 60 µs, and apply 11.5 - 12.5V to RESET.
5. 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.
6. Wait at least 300 µs before giving any parallel programming commands.
7. 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
alternative algorithm can be used.
1. Set Prog_enable pins listed in Table 129 on page 285 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 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.
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.
Chip Erase The Chip Erase will erase the Flash and EEPROM (1) memories plus Lock bits. The Lock
bits are not reset until the program memory has been completely erased. The Fuse bits
are not changed. A Chip Erase must be performed before the Flash and/or EEPROM
are reprogrammed.
Note: 1. The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is
programmed.
Load Command “Chip Erase”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS1 to “0”.
3. Set DATA to “1000 0000”. This is the command for Chip Erase.