ATMEGA644-20PU Atmel, ATMEGA644-20PU Datasheet - Page 22
ATMEGA644-20PU
Manufacturer Part Number
ATMEGA644-20PU
Description
IC AVR MCU FLASH 64K 40DIP
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA644-20PU
Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
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)
2.7 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
40-DIP (0.600", 15.24mm)
Processor Series
ATMEGA64x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
4 KB
Interface Type
2-Wire/SPI/USART
Maximum Clock Frequency
20 MHz
Number Of Programmable I/os
32
Number Of Timers
3
Operating Supply Voltage
2.7 V to 5.5 V
Maximum Operating Temperature
+ 85 C
Mounting Style
Through Hole
3rd Party Development Tools
EWAVR, EWAVR-BL
Development Tools By Supplier
ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATAVRRZ541, ATAVRRAVEN, ATAVRRZRAVEN, ATAVRRZUSBSTICK, ATAVRRZ201
Minimum Operating Temperature
- 40 C
On-chip Adc
8-ch x 10-bit
Controller Family/series
AVR MEGA
No. Of I/o's
32
Eeprom Memory Size
2KB
Ram Memory Size
4KB
Cpu Speed
20MHz
No. Of Timers
3
Rohs Compliant
Yes
Package
40PDIP
Device Core
AVR
Family Name
ATmega
Maximum Speed
20 MHz
For Use With
ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600-DIP40 - STK600 SOCKET/ADAPTER 40-PDIP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEM
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
ATMEGA644-20PU
Manufacturer:
Atmel
Quantity:
1 930
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ATmega644
Table 6-1.
• Bit 3 – EERIE: EEPROM Ready Interrupt Enable
Writing EERIE to one enables the EEPROM Ready Interrupt if the I-bit in SREG is set. Writing
EERIE to zero disables the interrupt. The EEPROM Ready interrupt generates a constant inter-
rupt when EEPE is cleared.
• Bit 2 – EEMPE: EEPROM Master Programming Enable
The EEMPE bit determines whether setting EEPE to one causes the EEPROM to be written.
When EEMPE is set, setting EEPE within four clock cycles will write data to the EEPROM at the
selected address If EEMPE is zero, setting EEPE will have no effect. When EEMPE has been
written to one by software, hardware clears the bit to zero after four clock cycles. See the
description of the EEPE bit for an EEPROM write procedure.
• Bit 1 – EEPE: EEPROM Programming Enable
The EEPROM Write Enable Signal EEPE is the write strobe to the EEPROM. When address
and data are correctly set up, the EEPE bit must be written to one to write the value into the
EEPROM. The EEMPE bit must be written to one before a logical one is written to EEPE, other-
wise no EEPROM write takes place. The following procedure should be followed when writing
the EEPROM (the order of steps 3 and 4 is not essential):
1. Wait until EEPE becomes zero.
2. Wait until SELFPRGEN 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 EEMPE bit while writing a zero to EEPE in EECR.
6. Within four clock cycles after setting EEMPE, write a logical one to EEPE.
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
gramming” on page 284
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.
When the write access time has elapsed, the EEPE bit is cleared by hardware. The user soft-
ware can poll this bit and wait for a zero before writing the next byte. When EEPE has been set,
the CPU is halted for two cycles before the next instruction is executed.
EEPM1
0
0
1
1
EEPM0
EEPROM Mode Bits
0
1
0
1
Programming
for details about Boot programming.
3.4 ms
1.8 ms
1.8 ms
Time
–
Operation
Erase and Write in one operation (Atomic Operation)
Erase Only
Write Only
Reserved for future use
”Memory Pro-
2593N–AVR–07/10
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