ATMega644 8-bit AVR microcontroller — 64KB flash, 4KB SRAM, 32 I/O, 40-DIP
The ATMega644 is a high-performance, low-power 8-bit AVR microcontroller from Microchip Technology (formerly Atmel), housed in a 40-pin DIP package. With 64KB of in-system programmable flash, 4KB SRAM, 2KB EEPROM, dual USARTs, and 32 general-purpose I/O lines, it is one of the most capable 8-bit AVR devices available — ideal for complex embedded applications that outgrow the ATMega328 but don’t require a 32-bit processor. It is fully supported by the Arduino IDE via the MightyCore board package.
Key Specifications:
- Architecture: 8-bit AVR RISC
- Flash memory: 64KB ISP (Read-While-Write capable)
- SRAM: 4KB
- EEPROM: 2KB
- GPIO: 32 programmable I/O lines (Ports A, B, C, D)
- ADC: 8-channel, 10-bit with differential input and programmable gain
- Timers: 2 × 8-bit + 1 × 16-bit Timer/Counter with PWM
- USART: 2 × full-duplex hardware USART
- SPI: 1 × master/slave SPI interface
- I²C (TWI): 1 × Two-Wire Interface
- JTAG: on-chip debug interface (ISP + JTAG programming)
- Clock: up to 20MHz (external crystal); internal 8MHz RC oscillator
- Operating voltage: 1.8V – 5.5V (ATMega644V: 1.8V–3.6V; ATMega644: 2.7V–5.5V)
- Power-saving modes: 6 modes (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, Extended Standby)
- Package: 40-pin DIP (through-hole)
Pinout Summary (40-DIP):
- Port A (PA0–PA7): ADC0–ADC7 / general I/O
- Port B (PB0–PB7): SPI, Timer OC, general I/O
- Port C (PC0–PC7): JTAG (TCK, TMS, TDO, TDI), general I/O
- Port D (PD0–PD7): USART0 RX/TX, USART1 RX/TX, INT0/INT1, general I/O
- VCC, GND, AVCC, AREF, RESET
Programming:
- ISP (In-System Programming) via SPI — compatible with USBasp, AVRISP mkII, Arduino as ISP
- JTAG programming and on-chip debugging
- Arduino IDE support via MightyCore board package (ATMega644/P/PA)
- Atmel Studio / Microchip Studio (C/C++ with AVR-GCC)
- avrdude command-line programmer
Applications:
- Industrial automation and control systems
- Multi-channel data acquisition (8-ch ADC)
- Dual serial communication systems
- Robotics and motor control
- Advanced Arduino-compatible projects requiring more I/O and memory
- Embedded systems education and prototyping
Note: The ATMega644 is available in several variants — ATMega644 (up to 20MHz, 2.7V–5.5V), ATMega644P (with USART in SPI mode), and ATMega644PA (picoPower). Verify the exact variant marking on the IC before programming fuse bits.