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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller QFN 64 (9x9) 8-Bit 16 MHz I/O number 53
291292293294295296297298299300
293
2490R–AVR–02/2013
ATmega64(L)
Latching of Fuses The fuse values are latched when the device enters Programming mode and changes of the
fuse values will have no effect until the part leaves Programming mode. This does not apply to
the EESAVE Fuse which will take effect once it is programmed. The fuses are also latched on
Power-up in Normal mode.
Signature Bytes All Atmel microcontrollers have a 3-byte signature code which identifies the device. This code
can be read in both Serial and Parallel mode, also when the device is locked. The three bytes
reside in a separate address space.
For the ATmega64 the signature bytes are:
1. 0x000: 0x1E (indicates manufactured by Atmel)
2. 0x001: 0x96 (indicates 64 Kbytes Flash memory)
3. 0x002: 0x02 (indicates ATmega64 device when 0x001 is 0x96)
Calibration Byte The ATmega64 stores four different calibration values for the internal RC Oscillator. These bytes
resides in the signature row high byte of the addresses 0x000, 0x0001, 0x0002, and 0x0003 for
1, 2, 4, and 8 MHz respectively. During Reset, the 1 MHz value is automatically loaded into the
OSCCAL Register. If other frequencies are used, the calibration value has to be loaded manu-
ally, see “OSCCAL – Oscillator Calibration Register(1)” on page 43 for details.
Parallel
Programming
Parameters, Pin
Mapping, and
Commands
This section describes how to parallel program and verify Flash Program memory, EEPROM
Data memory, Memory Lock bits, and Fuse bits in the ATmega64. Pulses are assumed to be at
least 250 ns unless otherwise noted.
Signal Names In this section, some pins of the ATmega64 are referenced by signal names describing their
functionality during parallel programming, see Figure 138 and Table 120. Pins not described in
the following table are referenced by pin names.
The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a positive pulse.
The bit coding is shown in Table 122.
When pulsing WR
or OE, the command loaded determines the action executed. The different
Commands are shown in Table 123.