Rainbow Electronics ATmega128L - Manual (Page 282)

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ATmega128(L)
2467B–09/01
Signature Bytes All Atmel microcontrollers have a three-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 ATmega128 the signature bytes are:
1. $000: $1E (indicates manufactured by Atmel)
2. $001: $97 (indicates 128KB Flash memory)
3. $002: $02 (indicates ATmega128 device when $001 is $97)
Calibration Byte The ATmega128 has a byte calibration value for the internal RC Oscillator. This byte
resides in the high byte of address $000 in the signature address space. During reset,
this byte is automatically written into the OSCCAL register to ensure correct frequency
of the calibrated RC oscillator.
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 ATmega128. Pulses
are assumed to be at least 250 ns unless otherwise noted.
Signal Names In this section, some pins of the ATmega128 are referenced by signal names describing
their functionality during parallel programming, see
Figure 135 and Table 121. 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 posi-
tive pulse. The bit coding is shown in
Table 123.
When pulsing WR or OE, the command loaded determines the action executed. The dif-
ferent Commands are shown in
Table 124.
Figure 135. Parallel Programming
VCC
+5V
GND
XTAL1
PD1
PD2
PD3
PD4
PD5
PD6
PB7 - PB0 DATA
RESET
PD7
+12 V
BS1
XA0
XA1
OE
RDY/BSY
PAGEL
PA0
WR
BS2