Datasheet

183
ATmega323(L)
1457E–11/01
Calibration Byte The ATmega323 has a one byte calibration value for the internal RC Oscillator. This
byte resides in the high byte of address $000 in the signature address space. To make
use of this byte, it should be read from this location and written into the normal Flash
program memory by the external programmer. At start-up, the user software must read
this Flash location and write the value to the OSCCAL register.
Parallel Programming This section describes how to parallel program and verify Flash Program memory,
EEPROM Data memory + Program And Data Memory Lock bits and Fuse bits in the
ATmega323. Pulses are assumed to be at least 500ns unless otherwise noted.
Signal Names In this section, some pins of the ATmega323 are referenced by signal names describing
their functionality during parallel programming, see Figure 93 and Table 64. 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 are shown in Table 65.
When pulsing WR
or OE, the command loaded determines the action executed. The
Command is a byte where the different bits are assigned functions as shown in Table
66.
Figure 93. Parallel Programming
Table 64. Pin Name Mapping
Signal Name in
Programming Mode
Pin
Name I/O Function
RDY/BSY PD1 O 0: Device is Busy Programming, 1: Device is
Ready for New Command
OE
PD2 I Output Enable (Active Low)
WR
PD3 I Write Pulse (Active Low)
BS1 PD4 I Byte Select 1 (“0” Selects Low Byte, “1” Selects
High Byte)
XA0 PD5 I XTAL Action Bit 0
XA1 PD6 I XTAL Action Bit 1
ATmega323
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