
508
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
Table 31-14. Command Byte Bit Encoding (EEPROM Erase, User Signature Data)
Command Byte
Command Executed
1000 0010
Chip Erase EEPROM only
1000 0011
Erase EEPROM Page
0001 0010
Write User Signature Page
(1)
1000 0100
Erase User Signature Page
(1)
0000 1000
Read User Signature Page
(1)
Note:
1. See section
31.8 Parallel Programming
Pulses of CLKI and in the following command sequences are assumed to be at least
250 ns wide unless otherwise noted.
31.8.1 Enter Programming Mode
The following algorithm puts the device in parallel programming mode:
1. Apply 3.3V between DEVDD and DVSS.
2. Set RSTN to 0 and TST to 0.
least 100ns.
4. Set TST to 1. TST can be set high any time before but not after the rising edge of
RSTN (tTSTRNH).
5. Set RSTN to 1. Any activity on Prog_enable pins within 100 ns after RSTN is set to 1
will cause the device to fail entering programming mode.
6. Wait at least 50 s before sending a command.
31.8.2 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.
31.8.3 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 changed. A Chip Erase must be performed before the Flash and/or
EEPROM are reprogrammed.
Note:
1. The EEPROM memory is preserved during Chip Erase if the EESAVE Fuse is
programmed.