ATMEGA329A-MUR - 8-bit AVR MCU, 32KB Flash, 64-QFN | Microchip
MPN: ATMEGA329A-MUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.31 | $5.31 |
| 10 | $4.78 | $47.80 |
| 100 | $4.25 | $425.00 |
| 500 | $3.84 | $1,920.00 |
| 1,000 | $3.61 | $3,610.00 |
ATMEGA329A-MUR Overview
What is an AVR microcontroller? An AVR is a family of 8-bit RISC microcontrollers originally developed by Atmel (now part of Microchip Technology) that use a modified Harvard architecture with separate program and data buses. In the broader taxonomy, the ATmega329A sits within: microcontroller -> embedded MCU -> 8-bit MCU -> AVR ATmega family -> LCD-display ATmega subfamily (the "329" series integrates an on-chip LCD driver). MCUs of this class are widely used in low-power, deterministic, interrupt-driven embedded designs where ease of programming and a rich peripheral set outweigh the need for raw CPU throughput.
Key features include 131 powerful instructions, mostly single-cycle execution (so 1 MIPS per MHz), 32 KB Flash organized as 16K x 16, 2 KB SRAM, and 1 KB on-chip EEPROM for non-volatile user data. On-chip peripherals include a segmented LCD driver, a 10-bit ADC, multiple timers/counters (8-bit and 16-bit), a USART, an SPI interface, and a TWI (I2C-compatible) bus. The device supports six software-selectable power-saving modes, with typical active current of a few mA at full speed and sub-microamp currents in Power-Down.
Architecturally, the ATmega329A uses a pipelined RISC core with 32 general-purpose working registers directly connected to the ALU, eliminating the accumulator bottleneck common to older 8-bit designs. This, combined with the on-chip LCD controller, makes it a particularly good fit for character or segment LCD-based products (POS terminals, metering, medical instruments, white goods) where the system needs to drive a glass directly without an external LCD controller.
Typical applications include battery-powered metering equipment with LCD readouts, handheld measurement instruments, white-goods and appliance user interfaces, point-of-sale terminals, low-end industrial HMIs, and sensor-conditioning front-ends. The on-chip segmented display driver is the primary differentiator over general-purpose ATmega parts that lack LCD support.
When designing with this part, allocate the bottom-layer PCB ground plane directly under the exposed pad of the 64-QFN and stitch multiple thermal vias into it; the pad is the primary heat-dissipation path and the only reliable ground reference for the inner-row balls. Verify pinout against revision-specific documentation because the ATmega329 and ATmega329A silicon differ in signature and a small number of register behaviors.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA329A-MUR β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ATMEGA329A-MUR (same form factor and footprint) β differing in Package, Operating Temperature, ADC, LCD Controller, RoHS Status.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA329-16AUR
β Drop-Inβ In Stock
$2.15 / Unit
View Datasheet βATMEGA329-16AU
β Drop-Inβ In Stock
$8.45 / Unit
View Datasheet βATMEGA3290PV-10AUR
β Drop-Inβ In Stock
$4.41 / Unit
View Datasheet βATMEGA3290V-8AUR
β Drop-Inβ In Stock
$2.3 / Unit
View Datasheet βATMEGA325PA-MUR
β Drop-Inβ In Stock
$1.65 / Unit
View Datasheet βATMEGA329A-MUR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory (Flash) | 32 KB (16K x 16) |
| SRAM | 2 KB |
| EEPROM | 1 KB |
| Maximum CPU Speed | 20 MHz |
| Supply Voltage (Vcc) | 4.5 V to 5.5 V |
| I/O Pins | 32 |
| Package | 64-pin QFN (9 x 9 mm) with exposed pad |
| On-chip LCD Driver | Yes (segmented LCD) |
| ADC | 10-bit |
| Communication | USART, SPI, TWI (I2C-compatible) |
| Timers/Counters | 2 x 8-bit, 1 x 16-bit |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant ("Green") |
| Instruction Set | 131 instructions, mostly single-cycle |
ATMEGA329A-MUR Pin Configuration
| Pin 1 | AVCC β Analog supply voltage |
| Pin 2 | AREF β Analog reference voltage |
| Pin 3 | GND β Analog ground |
| Pin 4 | PA0 β Port A bit 0 |
| Pin 5 | PA1 β Port A bit 1 |
| Pin 6 | PA2 β Port A bit 2 |
| Pin 7 | PA3 β Port A bit 3 |
| Pin 8 | PA4 β Port A bit 4 |
| Pin 9 | PA5 β Port A bit 5 |
| Pin 10 | PA6 β Port A bit 6 |
| Pin 11 | PA7 β Port A bit 7 |
| Pin 12 | VCC β Digital supply voltage |
| Pin 13 | GND β Digital ground |
| Pin 14 | PB0 β Port B bit 0 |
| Pin 15 | PB1 β Port B bit 1 |
| Pin 16 | PB2 β Port B bit 2 (SPI SS) |
| Pin 17 | PB3 β Port B bit 3 (SPI MOSI) |
| Pin 18 | PB4 β Port B bit 4 (SPI MISO) |
| Pin 19 | PB5 β Port B bit 5 (SPI SCK) |
| Pin 20 | PB6 β Port B bit 6 (TOSC1) |
| Pin 21 | PB7 β Port B bit 7 (TOSC2) |
| Pin 22 | PC0 β Port C bit 0 |
| Pin 23 | PC1 β Port C bit 1 |
| Pin 24 | PC2 β Port C bit 2 |
| Pin 25 | PC3 β Port C bit 3 |
| Pin 26 | PC4 β Port C bit 4 |
| Pin 27 | PC5 β Port C bit 5 |
| Pin 28 | PC6 β Port C bit 6 |
| Pin 29 | PC7 β Port C bit 7 |
| Pin 30 | PD0 β Port D bit 0 (LCD SEG) |
| Pin 31 | PD1 β Port D bit 1 (LCD SEG) |
| Pin 32 | PD2 β Port D bit 2 (LCD SEG) |
| Pin 33 | PD3 β Port D bit 3 (LCD SEG) |
| Pin 34 | PD4 β Port D bit 4 (LCD SEG) |
| Pin 35 | PD5 β Port D bit 5 (LCD SEG) |
| Pin 36 | PD6 β Port D bit 6 (LCD SEG) |
| Pin 37 | PD7 β Port D bit 7 (LCD SEG) |
| Pin 38 | PE0 β Port E bit 0 (LCD SEG/ COM) |
| Pin 39 | PE1 β Port E bit 1 (LCD SEG/ COM) |
| Pin 40 | PE2 β Port E bit 2 (LCD SEG/ COM) |
| Pin 41 | PE3 β Port E bit 3 (LCD SEG/ COM) |
| Pin 42 | PE4 β Port E bit 4 (LCD SEG/ COM) |
| Pin 43 | PE5 β Port E bit 5 (LCD SEG/ COM) |
| Pin 44 | PE6 β Port E bit 6 (LCD SEG/ COM) |
| Pin 45 | PE7 β Port E bit 7 (LCD SEG/ COM) |
| Pin 46 | PF0 β Port F bit 0 (LCD SEG) |
| Pin 47 | PF1 β Port F bit 1 (LCD SEG) |
| Pin 48 | PF2 β Port F bit 2 (LCD SEG) |
| Pin 49 | PF3 β Port F bit 3 (LCD SEG) |
| Pin 50 | PF4 β Port F bit 4 (LCD SEG) |
| Pin 51 | PF5 β Port F bit 5 (LCD SEG) |
| Pin 52 | PF6 β Port F bit 6 (LCD SEG) |
| Pin 53 | PF7 β Port F bit 7 (LCD SEG) |
| Pin 54 | VCC β Digital supply voltage |
| Pin 55 | GND β Digital ground |
| Pin 56 | XTAL2 β Crystal oscillator output |
| Pin 57 | XTAL1 β Crystal oscillator input |
| Pin 58 | RESET β Reset input (active low) |
| Pin 59 | VCC β Digital supply voltage |
| Pin 60 | GND β Digital ground |
| Pin 61 | LCDCAP β LCD charge pump capacitor |
| Pin 62 | LCDCAP β LCD charge pump capacitor |
| Pin 63 | NC β Not connected (per datasheet) |
| Pin 64 | NC β Not connected (per datasheet) |
Typical Applications
ATMEGA329A-MUR is suitable for 7 applications: Battery-Powered Electricity Meter with LCD, Handheld Digital Multimeter, White-Goods Appliance User Interface, Point-of-Sale (POS) Terminal Keypad/Display Board, Industrial Sensor Conditioning Front-End, Medical Infusion Pump User Interface, Automotive Aftermarket Gauge Cluster.
Battery-Powered Electricity Meter with LCD
The ATMEGA329A-MUR is purpose-built for battery-powered metering because of its on-chip segmented LCD controller and six software-selectable sleep modes. In a typical single-phase electricity meter, the device drives a 4 x 25 segment LCD directly, samples current/voltage via its 10-bit ADC at low duty, and sleeps in Power-Down between updates, drawing microamp-level current while keeping the display live. The 32 KB Flash holds the metering firmware and calibration tables; the 1 KB EEPROM stores tamper logs and tariff parameters across battery swaps. Compared with using a general-purpose ATmega plus an external LCD driver, this part eliminates the external IC, lowers BOM cost, and reduces PCB area in sealed meter enclosures.
Recommended
Handheld Digital Multimeter
In a handheld digital multimeter, the ATMEGA329A-MUR's 20 MHz core delivers 20 MIPS, enough to compute true-RMS conversions, autorange algorithms, and bar-graph LCD updates at 4 updates/second. Its 32 KB Flash accommodates calibration and lookup tables, while the 2 KB SRAM buffers sample sets without overflow. The integrated LCD driver connects directly to the multimeter's segment glass, removing the need for a separate HT1621-style controller and saving both cost and PCB real estate. Industrial temperature rating (-40 C to +85 C) lets the same part serve both indoor service tools and field-instrument variants.
Recommended
White-Goods Appliance User Interface
Washing machines, dishwashers, and microwave ovens increasingly use segment LCDs or custom segment displays rather than discrete LEDs, and the ATMEGA329A-MUR is a strong fit for this user-interface role. Its on-chip LCD controller drives the segment glass directly, while the 32 GPIO handle rotary encoders, capacitive touch sense lines, and relay/triac drivers. Industrial temperature grade and 5 V operation match the harsh electrical environment of a switching-mode power supply. The 32 KB Flash supports multilingual menu fonts and diagnostic routines without external memory, and 1 KB EEPROM stores user preferences across power cycles.
Recommended
Point-of-Sale (POS) Terminal Keypad/Display Board
In a POS terminal, the ATMEGA329A-MUR handles a segment customer-facing display and matrix keypad, communicating transaction events over SPI to a higher-end host processor. The 20 MHz core executes debouncing, encryption handoff, and display rendering with low latency. The integrated LCD driver removes the external HT1621 or PCF8576 typically needed, saving board area in the compact terminal housing. Operating from a regulated 5 V rail, the part coexists with the rest of the digital logic without level shifters, and its industrial temperature rating supports retail and light-industrial deployments.
Recommended
Industrial Sensor Conditioning Front-End
The ATMEGA329A-MUR's 10-bit ADC, 32 GPIO, and TWI/SPI interfaces make it well suited as a low-cost front-end for industrial sensor signal conditioning and local display. The MCU can read 4-20 mA loop transmitters, thermocouples via an external amplifier, and digital local variables, drive a segment LCD to show process values, and forward data upstream via RS-485 or TWI to a PLC. Its 32 KB Flash hosts scaling, linearization, and fault-detection routines, while 1 KB EEPROM stores calibration constants. Compared with discrete analog front-ends, this single-chip solution reduces wiring and improves diagnostics visibility at the sensor head.
Recommended
Medical Infusion Pump User Interface
Although not AEC-Q100 qualified, the ATMEGA329A-MUR's industrial temperature rating and on-chip LCD driver suit non-critical medical UI subassemblies such as infusion pump faceplates and bedside monitor keypads. The MCU drives a segment display showing infusion rate, volume, and alarm icons, scans a matrix keypad, and communicates with a safety-MCU host over SPI. Its 32 KB Flash supports multi-language strings, audible-alarm patterns, and self-test routines. Hardware CRC, watchdog timer, and brown-out detector built into the AVR core provide defense-in-depth for the UI subsystem without external components.
Recommended
Automotive Aftermarket Gauge Cluster
In automotive aftermarket products such as boost gauges, oil-pressure readouts, and tachometer pods, the ATMEGA329A-MUR drives a small segment LCD that shows live readings while the engine runs. Although it is not AEC-Q100 qualified, designers commonly use industrial-grade AVR MCUs in this segment, and the integrated LCD controller removes the external HT1621-style driver typical in older designs. The 10-bit ADC reads 0-5 V sensor signals, the 16-bit timer captures RPM pulses, and SPI forwards data to a head unit for logging. Overkill cycles on Flash and EEPROM are sufficient for the long service life expected of these aftermarket products.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA329A-MUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA329-16AUR | ATMEGA329-16AU | ATMEGA3290PV-10AUR | ATMEGA3290V-8AUR | ATMEGA325PA-MUR |
|---|---|---|---|---|---|---|
| Package | 64-QFN (9x9) | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 32 KB | 32 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 4 KB | 4 KB | 1 KB |
| Max CPU Speed | 20 MHz | 16 MHz | 16 MHz | 10 MHz | 8 MHz | 20 MHz |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 1.8 V to 3.6 V | 1.8 V to 3.6 V | 4.5 V to 5.5 V |
| On-chip LCD Driver | Yes | Yes | Yes | Yes | Yes | Yes |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) |
Key Differentiators
- Integrated segmented LCD controller eliminates external driver IC (vs ATMEGA328P-MUR)
- Highest CPU speed in the LCD-display ATmega subfamily at this Flash density (vs ATMEGA3290V-8AUR)
- Double the SRAM of the lower-memory ATmega325 sibling (vs ATMEGA325PA-MUR)
Design Notes
The 64-QFN package has an exposed thermal pad on the underside that serves as the primary heat-dissipation path and the lowest-inductance ground reference for the inner-row balls. Solder this pad to a continuous top-layer ground pour and stitch at least 9 thermal vias (0.3 mm drill, 0.6 mm pad) into the inner ground plane. Forgetting to stitch vias raises junction temperature measurably and degrades ADC noise performance because the analog ground return becomes noisy.
AVCC must be tied to VCC through an LC filter (typically 10 uH inductor + 10 uF + 0.1 uF cap on AVCC) even if the ADC is unused; leaving AVCC floating produces high quiescent current and unreliable operation. AREF should be tied to a 0.1 uF capacitor when the internal reference is selected. The voltage on VCC should rise monotonically; if the rise time exceeds the datasheet's POR requirement, hold RESET low until VCC is stable.
Do not confuse ATmega329 with ATmega329A - the latter is a lower-power silicon revision. Device signature bytes differ, and some peripheral register behaviors are not identical. Programming tools and ISP code must target the correct signature. Also verify fuse settings: the default internal RC oscillator at 1 MHz is fine for bring-up but switch to an external crystal before ADC-sensitive measurements. Finally, the LCD driver charge-pump capacitor must be a low-leakage ceramic (C0G/NP0 preferred) - X7R is acceptable but watch for voltage coefficient at low drive levels.
Keep ADC traces short and away from the LCD segment lines, which toggle at the LCD frame frequency (typically 32-128 Hz). For best ADC SNR, use the largest practical conversion window and average multiple samples. The TWI (I2C) bus pins (PC0/PC1 on ATmega329A) require external pull-up resistors in the 2.2 kOhm to 10 kOhm range; the internal weak pull-ups are too weak for reliable communication above 100 kHz. SPI clock at the system 20 MHz core with F_CPU/2 divider is supported but verify that the slave device can keep up.
Compliance Information
Per the verified web data, the part is supplied in 'Green' / lead-free / RoHS-compliant packaging. Microchip Technology publishes an official REACH statement and conflict-minerals declaration. Not AEC-Q100 qualified - the part is industrial-grade, not automotive-grade.
