Rainbow Electronics ATmega128L - Manual (Page 284)

284
ATmega128(L)
2467B–09/01
Parallel Programming
Enter Programming Mode The following algorithm puts the device in parallel programming mode:
1. Apply 4.5 - 5.5 V between V
CC
and GND.
2. Set RESET to “0” and toggle XTAL1 at least 6 times
3. Set the Prog_enable pins listed in Table 122 on page 283 to “0000” and wait at
least 100 ns.
4. Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns
after +12V has been applied to RESET, will cause the device to fail entering pro-
gramming mode.
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 $FF, 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 is 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”.
0000 1000 Read Signature Bytes and Calibration byte
0000 0100 Read Fuse and Lock Bits
0000 0010 Read Flash
0000 0011 Read EEPROM
Table 125. No. of Words in a Page and no. of Pages in the Flash
Flash Size Page Size PCWORD No. of Pages PCPAGE PCMSB
64K words (128K bytes) 128 words PC[6:0] 512 PC[15:7] 15
Table 126. No. of Words in a Page and no. of Pages in the EEPROM
EEPROM Size Page Size PCWORD No. of Pages PCPAGE EEAMSB
4K bytes 8 bytes EEA[2:0] 512 EEA[11:3] 8
Table 124. Command Byte Bit Coding
Command Byte Command Executed