ATMEGA1284-AUR - 8-Bit AVR MCU 128KB Flash 20MHz | Microchip
MPN: ATMEGA1284-AUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.62 | $6.62 |
| 10 | $6.05 | $60.50 |
| 100 | $5.42 | $542.00 |
| 500 | $4.98 | $2,490.00 |
| 1,000 | $4.61 | $4,610.00 |
ATMEGA1284-AUR Overview
An AVR microcontroller is a Harvard-architecture 8-bit RISC device that executes most instructions in a single clock cycle, sitting in the hierarchy: AVR MCU -> 8-bit microcontroller -> microcontroller unit (MCU) -> embedded processor -> semiconductor IC. The ATmega family is the classic general-purpose AVR line, widely used where deterministic timing, low power, and 5 V-tolerant I/O matter more than raw compute.
The ATMEGA1284-AUR integrates 32 general-purpose I/O lines, 32 general-purpose working registers, three flexible timer/counters with compare modes and PWM, two USARTs, a byte-oriented two-wire serial interface, an 8-channel 10-bit ADC, and a programmable watchdog timer with internal oscillator. picoPower technology keeps active and idle current low for battery-powered designs.
Architecturally, the device uses 131 powerful instructions with fully static operation down to 0 Hz, enabling sleep modes that retain SRAM contents. The 128 KB flash supports read-while-write, allowing bootloader-based field firmware updates without an external programmer. The 16 KB SRAM is unusually large for an 8-bit MCU, which suits buffering-heavy applications such as protocol gateways and data loggers.
Typical applications include industrial control panels, home automation gateways, battery-powered sensor nodes, motor control front-ends, and legacy 5 V system upgrades. The 44-pin TQFP footprint is shared with the ATmega164/324/644 family, enabling code and PCB reuse across memory sizes.
When designing with this device, decouple every VCC pin with a 100 nF ceramic capacitor placed close to the pin, and keep the AREF pin bypassed with 100 nF plus a 10 uF bulk capacitor for ADC accuracy. The reset pin requires an external pull-up and must not be left floating.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single reference for sourcing and layout decisions.
Drop-in alternatives for ATMEGA1284-AUR β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA1284P-AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA1284-AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA1284P-AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA644A-AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA324A-AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA1284-AUR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory Size | 128 KB ISP Flash (64K x 16) |
| SRAM | 16 KB |
| EEPROM | 4 KB |
| Maximum Clock Frequency | 20 MHz |
| Throughput | Up to 20 MIPS at 20 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V |
| Operating Voltage (Full 20 MHz) | 2.7 V to 5.5 V |
| General Purpose I/O Lines | 32 |
| General Purpose Working Registers | 32 |
| Instruction Set | 131 powerful instructions, most single-clock cycle |
| ADC | 8-channel, 10-bit successive approximation |
| USART Interfaces | 2 |
| Timer/Counters | 3 flexible timer/counters with compare modes and PWM |
| Package | 44-pin TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel |
| Operating Temperature | -40C to +85C |
| RoHS Status | Compliant |
| Lifecycle Stage | Active |
ATMEGA1284-AUR Pin Configuration
| Pin 1 | PB0 β Port B bit 0 / T0 / XCK0 / PCINT8 |
| Pin 2 | PB1 β Port B bit 1 / T1 / CLKO / PCINT9 |
| Pin 3 | PB2 β Port B bit 2 / INT2 / AIN0 / PCINT10 |
| Pin 4 | PB3 β Port B bit 3 / OC0A / AIN1 / PCINT11 |
| Pin 5 | PB4 β Port B bit 4 / OC0B / SS / PCINT12 |
| Pin 6 | PB5 β Port B bit 5 / MOSI / OC1A / PCINT13 |
| Pin 7 | PB6 β Port B bit 6 / MISO / OC1B / PCINT14 |
| Pin 8 | PB7 β Port B bit 7 / SCK / OC2A / PCINT15 |
| Pin 9 | RESET β Reset input, active low |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Crystal oscillator output / inverted oscillator input |
| Pin 13 | XTAL1 β Crystal oscillator input / inverted oscillator output |
| Pin 14 | PD0 β Port D bit 0 / RXD0 / PCINT16 |
| Pin 15 | PD1 β Port D bit 1 / TXD0 / PCINT17 |
| Pin 16 | PD2 β Port D bit 2 / RXD1 / INT0 / PCINT18 |
| Pin 17 | PD3 β Port D bit 3 / TXD1 / INT1 / PCINT19 |
| Pin 18 | PD4 β Port D bit 4 / OC1B / PCINT20 |
| Pin 19 | PD5 β Port D bit 5 / OC1A / PCINT21 |
| Pin 20 | PD6 β Port D bit 6 / OC2B / PCINT22 |
| Pin 21 | PD7 β Port D bit 7 / T0 / PCINT23 |
| Pin 22 | PC0 β Port C bit 0 / SCL / PCINT24 |
| Pin 23 | PC1 β Port C bit 1 / SDA / PCINT25 |
| Pin 24 | PC2 β Port C bit 2 / TCK / PCINT26 |
| Pin 25 | PC3 β Port C bit 3 / TMS / PCINT27 |
| Pin 26 | PC4 β Port C bit 4 / TDO / PCINT28 |
| Pin 27 | PC5 β Port C bit 5 / TDI / PCINT29 |
| Pin 28 | PC6 β Port C bit 6 / TOSC1 / PCINT30 |
| Pin 29 | PC7 β Port C bit 7 / TOSC2 / PCINT31 |
| Pin 30 | AVCC β Analog supply voltage for ADC |
| Pin 31 | GND β Ground |
| Pin 32 | AREF β Analog reference voltage for ADC |
| Pin 33 | PA7 β Port A bit 7 / ADC7 / PCINT7 |
| Pin 34 | PA6 β Port A bit 6 / ADC6 / PCINT6 |
| Pin 35 | PA5 β Port A bit 5 / ADC5 / PCINT5 |
| Pin 36 | PA4 β Port A bit 4 / ADC4 / PCINT4 |
| Pin 37 | PA3 β Port A bit 3 / ADC3 / PCINT3 |
| Pin 38 | PA2 β Port A bit 2 / ADC2 / PCINT2 |
| Pin 39 | PA1 β Port A bit 1 / ADC1 / PCINT1 |
| Pin 40 | PA0 β Port A bit 0 / ADC0 / PCINT0 |
| Pin 41 | VCC β Digital supply voltage |
| Pin 42 | GND β Ground |
| Pin 43 | GND β Ground |
| Pin 44 | GND β Ground |
Typical Applications
ATMEGA1284-AUR is suitable for 6 applications: Industrial Control Panels, Home Automation Gateways, Battery-Powered Sensor Nodes, Motor Control Front-Ends, Data Loggers and Instrumentation, Legacy 5 V System Upgrades.
Industrial Control Panels
The ATMEGA1284-AUR fits industrial control panels because its 32 GPIO lines, three timer/counters, and 5 V-tolerant I/O interface directly with relays, opto-isolators, and 24 V field wiring through simple level shifting. The 16 KB SRAM buffers Modbus RTU frames and machine-state tables without external memory, while the 128 KB flash holds ladder-logic interpreters and HMI menus. Running at 20 MHz from a 5 V rail, the device executes control loops deterministically in single-clock cycles, which matters for safety interlocks. A typical topology places the MCU behind a digital isolator on the field side, with the 8-channel 10-bit ADC sampling thermistor and 4-20 mA loops. Unlike a 3.3 V ARM Cortex-M0, the ATmega1284-AUR drives 5 V logic directly, eliminating level shifters but consuming more active current at 20 MHz.
Recommended
Home Automation Gateways
The ATMEGA1284-AUR suits home automation gateways because two USARTs allow simultaneous Zigbee or RS-485 module communication plus a debug console, while the two-wire serial interface talks to EEPROM and sensor hubs. The 128 KB flash stores protocol stacks for KNX, Modbus, and proprietary RF, and the 16 KB SRAM buffers scene tables and event queues. At 3.3 V and 8 MHz, active current stays low enough for always-on gateway duty, and picoPower sleep modes on the P variant extend battery backup. A common topology uses USART0 for the RF transceiver and USART1 for the host bridge, with timer/counter PWM driving status LEDs. Compared with an ESP32, the ATmega1284-AUR lacks Wi-Fi but offers deterministic timing and 5 V tolerance for legacy wired buses.
Recommended
Battery-Powered Sensor Nodes
The ATMEGA1284-AUR works in battery-powered sensor nodes because its 1.8 V minimum supply and fully static core allow aggressive clock scaling and sleep between measurements. The 8-channel 10-bit ADC samples thermistors, strain gauges, and photodiodes directly, while the programmable watchdog timer with internal oscillator wakes the MCU periodically without an external clock. The 16 KB SRAM buffers burst samples so the radio transmits in efficient packets, and 4 KB EEPROM stores calibration coefficients across power cycles. A typical design runs at 1 MHz from a 2 V coin cell, waking every 60 seconds to sample and transmit. Compared with an MSP430, the ATmega1284-AUR offers more SRAM and 5 V tolerance but higher active current at equal clock speed.
Recommended
Motor Control Front-Ends
The ATMEGA1284-AUR serves motor control front-ends because three flexible timer/counters with compare modes and PWM generate complementary drive signals for H-bridge and three-phase inverter stages. The 20 MHz core computes PID loops fast enough for brushed DC and stepper commutation, and the 8-channel 10-bit ADC reads current-sense shunts and back-EMF dividers. The 32 GPIO lines drive gate-driver enable, fault, and direction pins directly at 5 V. A typical topology uses Timer1 in phase-correct PWM mode for the H-bridge and Timer0 for step timing, with the analog comparator for overcurrent trip. Unlike a dedicated motor-control DSP, the ATmega1284-AUR trades math throughput for deterministic timing and simpler firmware.
Recommended
Data Loggers and Instrumentation
The ATMEGA1284-AUR fits data loggers because 16 KB SRAM buffers high-rate sample streams before writing to SD card or serial flash, and 4 KB EEPROM stores configuration and calibration without external memory. The 128 KB flash holds FAT filesystem code, CSV formatting, and real-time clock drivers, while two USARTs connect a GPS module and a host PC simultaneously. The 8-channel 10-bit ADC digitizes analog sensors, and the byte-oriented two-wire interface reads external RTC and temperature sensors. A typical design samples at 1 kHz into a circular SRAM buffer, flushing to SD card every second. Compared with an STM32F103, the ATmega1284-AUR has less flash but simpler 5 V interfacing and a well-understood toolchain.
Recommended
Legacy 5 V System Upgrades
The ATMEGA1284-AUR is a natural upgrade path for legacy 5 V systems because it is pin-compatible with the ATmega164A, ATmega324A, and ATmega644A in the 44-pin TQFP footprint, allowing a drop-in memory upgrade without PCB respin. The 5.5 V maximum supply and 5 V-tolerant I/O interface directly with legacy peripherals such as HD44780 LCDs, 74HC logic, and RS-232 transceivers. The 128 KB flash accommodates expanded firmware that would not fit in a 64 KB ATmega644A, and 16 KB SRAM supports larger buffers. A typical migration replaces an ATmega644A on an existing board, recompiles firmware with the ATmega1284 device profile, and updates fuse bits. The trade-off is higher unit cost than the smaller-flash family members.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA1284-AUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA1284P-AUR | ATMEGA1284-AU | ATMEGA644A-AUR | ATMEGA324A-AUR |
|---|---|---|---|---|---|
| Package | 44-pin TQFP (10x10 mm) | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same | 44-pin TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 128 KB | 128 KB | 128 KB | 64 KB | 32 KB |
| SRAM | 16 KB | 16 KB | 16 KB | 4 KB | 2 KB |
| EEPROM | 4 KB | 4 KB | 4 KB | 2 KB | 1 KB |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| GPIO Lines | 32 | 32 | 32 | 32 | 32 |
| picoPower Low-Power Modes | No | Yes | No | No | No |
| Packaging | Tape & Reel | Tape & Reel | Tray/Tube | Tape & Reel | Tape & Reel |
Key Differentiators
- Largest SRAM in the 44-pin ATmega family (vs ATMEGA644A-AUR)
- Double the flash of the next family member (vs ATMEGA644A-AUR)
- Tape-and-reel packaging for automated assembly (vs ATMEGA1284-AU)
- Upgrade path to picoPower without redesign (vs ATMEGA1284P-AUR)
Design Notes
Decouple every VCC pin (pins 10 and 41) with a 100 nF ceramic capacitor placed within 5 mm of the pin, and add a 10 uF bulk capacitor near the board power entry. The AVCC pin (pin 30) requires its own 100 nF capacitor plus a 10 uH inductor or ferrite bead from VCC to isolate ADC noise. AREF (pin 32) should be bypassed with 100 nF and, for ratiometric measurements, tied to AVCC through a 10 uF capacitor. Estimated: at 20 MHz and 5 V, active current is roughly 10-15 mA, so a 100 nF decoupling capacitor per VCC pin keeps supply ripple below the ADC noise floor.
Keep the crystal or resonator loop between XTAL1 (pin 13) and XTAL2 (pin 12) as short as possible, with load capacitors returned to a local ground plane directly under the device. Route the RESET pin (pin 9) with a 10 kOhm pull-up to VCC and a 100 nF capacitor to ground, and keep the trace away from switching nodes to avoid spurious resets. Place the ISP header close to the MCU so MOSI, MISO, SCK, and RESET traces stay under 50 mm for reliable in-system programming.
Do not leave the RESET pin floating - it must have an external pull-up, otherwise noise can trigger unintended resets. Ensure the brown-out detector fuse is enabled for 5 V designs to prevent flash corruption during slow supply ramps. When migrating from an ATmega644A, update the device signature and fuse settings in the programmer, and recompile with the ATmega1284 device profile; the pinout is identical but the memory map and vector table differ. Verify that the bootloader, if used, is built for the 128 KB flash size.
Compliance Information
Distributor listings and the Microchip product page indicate RoHS compliance and lead-free construction. REACH, halogen-free, and conflict-minerals status were not stated in the retrieved data and are marked unknown rather than assumed. The device is not AEC-Q100 qualified; automotive designs require a separately qualified part.
