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AT90USB646 Datasheet(PDF) 372 Page - ATMEL Corporation |
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AT90USB646 Datasheet(HTML) 372 Page - ATMEL Corporation |
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372 / 459 page  372 7593H–AVR–11/08 ATmega32U6/AT90USB64/128 29.6 Parallel Programming 29.6.1 Enter Programming Mode The following algorithm puts the device in parallel programming mode: 1. Apply 4.5 - 5.5V between V CC and GND. 2. Set RESET to “0” and toggle XTAL1 at least six times. 3. Set the Prog_enable pins listed in Table 29-8 on page 371 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 programming mode. 5. Wait at least 50 µs before sending a new command. 29.6.2 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. 29.6.3 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 Table 29-11. No. of Words in a Page and No. of Pages in the Flash Flash Size Page Size PCWORD No. of Pages PCPAGE PCMSB 16K words (32K bytes) 64 words PC[6:0] 256 PC[13:7] 13 32K words (64K bytes) 128 words PC[6:0] 256 PC[14:7] 14 64K words (128K bytes) 128 words PC[6:0] 512 PC[15:7] 15 Table 29-12. No. of Words in a Page and No. of Pages in the EEPROM EEPROM Size Page Size PCWORD No. of Pages PCPAGE EEAMSB 1K bytes 4 bytes EEA[2:0] 256 EEA[9:3] 9 2K bytes 8 bytes EEA[2:0] 256 EEA[10:3] 10 4K bytes 8 bytes EEA[2:0] 512 EEA[11:3] 11 |
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