ATMEGA6450A-AU Atmel, ATMEGA6450A-AU Datasheet - Page 21
![IC MCU AVR 64K FLASH 100TQFP](/photos/6/70/67048/313-100-tqfp_sml.jpg)
ATMEGA6450A-AU
Manufacturer Part Number
ATMEGA6450A-AU
Description
IC MCU AVR 64K FLASH 100TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA6450A-AU
Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
SPI, UART/USART, USI
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
69
Program Memory Size
64KB (32K x 16)
Program Memory Type
FLASH
Eeprom Size
2K x 8
Ram Size
4K x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
100-TFQFP
Processor Series
ATmega
Core
AVR
Data Bus Width
8 bit
Data Ram Size
4 KB
Interface Type
SPI, USART
Maximum Clock Frequency
20 MHz
Number Of Programmable I/os
69
Number Of Timers
3
Operating Supply Voltage
3.3 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Operating Temperature Range
- 40 C to + 85 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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Manufacturer
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Price
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7.3
7.3.1
8285B–AVR–03/11
EEPROM Data Memory
EEPROM Read/Write Access
ATmega165A/165PA/325A/325PA/3250A/3250PA/6
The ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/6450A/6450P contains 512
bytes of data EEPROM memory. It is organized as a separate data space, in which single bytes
can be read and written. The EEPROM has an endurance of at least 100,000 write/erase cycles.
This section describes the access between the EEPROM and the CPU, specifying the EEPROM
Address Registers, the EEPROM Data Register, and the EEPROM Control Register.
For a detailed description of SPI, JTAG and Parallel data downloading to the EEPROM, see
”Serial Downloading” on page
”Parallel Programming Parameters, Pin Mapping, and Commands” on page 286
The EEPROM Access Registers are accessible in the I/O space.
The write access time for the EEPROM is given in
however, lets the user software detect when the next byte can be written. If the user code con-
tains instructions that write the EEPROM, some precautions must be taken. In heavily filtered
power supplies, V
some period of time to run at a voltage lower than specified as minimum for the clock frequency
used. See
these situations.
In order to prevent unintentional EEPROM writes, a specific write procedure must be followed.
When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction is
executed. When the EEPROM is written, the CPU is halted for two clock cycles before the next
instruction is executed.
The following procedure should be followed when writing the EEPROM (the order of steps 3 and
4 is not essential). See
register bit:
1. Wait until EEWE becomes zero.
2. Wait until SPMEN in SPMCSR becomes zero.
3. Write new EEPROM address to EEAR (optional).
4. Write new EEPROM data to EEDR (optional).
5. Write a logical one to the EEMWE bit while writing a zero to EEWE in EECR.
6. Within four clock cycles after setting EEMWE, write a logical one to EEWE.
The EEPROM can not be programmed during a CPU write to the Flash memory. The software
must check that the Flash programming is completed before initiating a new EEPROM write.
Step 2 is only relevant if the software contains a Boot Loader allowing the CPU to program the
Flash. If the Flash is never being updated by the CPU, step 2 can be omitted. See
Support – Read-While-Write Self-Programming” on page 266
programming.
Caution: An interrupt between step 5 and step 6 will make the write cycle fail, since the
EEPROM Master Write Enable will time-out. If an interrupt routine accessing the EEPROM is
interrupting another EEPROM access, the EEAR or EEDR Register will be modified, causing the
interrupted EEPROM access to fail. It is recommended to have the Global Interrupt Flag cleared
during all the steps to avoid these problems.
”Preventing EEPROM Corruption” on page 24
CC
is likely to rise or fall slowly on power-up/down. This causes the device for
”Register Description” on page 26
298,
”Programming via the JTAG Interface” on page
Table 7-1 on page
for details on how to avoid problems in
for supplementary description for each
22. A self-timing function,
for details about Boot
respectively.
”Boot Loader
304, and
21
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