271
AT90PWM216/316 [DATASHEET]
7710H–AVR–07/2013
24.8
Parallel Programming
24.8.1
Enter Programming Mode
The following algorithm puts the device in Parallel (High-voltage) > Programming mode:
1.
Set Prog_enable pins listed in
Table 24-8. to “0000”, RESET pin to “0” and Vcc to 0V.
2.
Apply 4.5 - 5.5V between VCC and GND. Ensure that Vcc reaches at least 1.8V within the next 20s.
3.
Wait 20 - 60s, 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 300s 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 Vcc is unable to fulfill the requirements listed above, the following alternative algorithm can be
used.
1.
Set Prog_enable pins listed in
Table 24-8. to “0000”, RESET pin to “0” and Vcc to 0V.
2.
Apply 4.5 - 5.5V between VCC and GND.
3.
Monitor Vcc, 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 Vcc 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.
24.8.2
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.
24.8.3
Chip Erase
The Chip Erase will erase the Flash and EEP
ROM(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.
4.
Give XTAL1 a positive pulse. This loads the command.
5.
Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low.
6.
Wait until RDY/BSY goes high before loading a new command.