atmega323l ATMEL Corporation, atmega323l Datasheet - Page 17

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Relative Program Addressing,
RJMP and RCALL
The EEPROM Data
Memory
Memory Access Times
and Instruction
Execution Timing
1457G–AVR–09/03
Figure 20. Relative Program Memory Addressing
Program execution continues at address PC + k + 1. The relative address k is from –
2048 to 2047.
The ATmega323 contains 1K bytes of data EEPROM Memory. It is organized as a sep-
arate data space, in which single bytes can be read and written. The EEPROM has an
endurance of at least 100,000 write/erase cycles. The access between the EEPROM
and the CPU is described on page 66 specifying the EEPROM Address Registers, the
EEPROM Data Register, and the EEPROM Control Register.
For SPI data downloading of the EEPROM, see page 197 for a detailed description.
This section describes the general access timing concepts for instruction execution and
internal memory access.
The AVR CPU is driven by the System Clock Ø, directly generated from the selected
clock source for the chip. No internal clock division is used.
Figure 21 shows the parallel instruction fetches and instruction executions enabled by
the Harvard architecture and the fast-access Register File concept. This is the basic
pipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results
for functions per cost, functions per clocks, and functions per power-unit.
Figure 21. The Parallel Instruction Fetches and Instruction Executions
Figure 22 shows the internal timing concept for the Register File. In a single clock cycle
an ALU operation using two register operands is executed, and the result is stored back
to the destination register.
2nd Instruction Execute
3rd Instruction Execute
1st Instruction Execute
2nd Instruction Fetch
3rd Instruction Fetch
4th Instruction Fetch
1st Instruction Fetch
System Clock Ø
1
T1
T2
ATmega323(L)
T3
T4
$3FFF
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