ATMEGA323-8PI - 8-bit AVR MCU 32KB Flash 8MHz DIP-40 | Microchip
MPN: ATMEGA323-8PI β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.9 | $6.90 |
| 10 | $6.21 | $62.10 |
| 100 | $5.52 | $552.00 |
| 500 | $4.97 | $2,485.00 |
| 1,000 | $4.48 | $4,480.00 |
ATMEGA323-8PI Overview
A microcontroller unit (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals on one die. The AVR ATmega family sits within the 8-bit microcontroller hierarchy, widely used in embedded control, industrial automation, and legacy system maintenance. The ATmega323 belongs to the high-performance, low-power AVR product line originally developed by Atmel, now owned by Microchip Technology.
Key features include the Advanced RISC architecture with 131 powerful instructions, most executing in a single clock cycle, and fully static operation delivering up to 16 MIPS throughput at 16MHz (8 MIPS at the 8MHz grade of this part). The device provides 32KB (16K x 16) self-programmable Flash, 2KB internal SRAM, 1KB EEPROM for nonvolatile data, a JTAG interface for on-chip debugging and boundary scan, plus USART, SPI, and TWI serial interfaces and an 8-channel 10-bit ADC.
Technically, the ATmega323 was the first ATmega device to add JTAG on-chip debug, and its Harvard-architecture core fetches instructions and data over separate buses. Boot-section Flash with read-while-write support enables in-system firmware updates, while in-circuit programming via SPI allows field programming without removing the device from the PCB.
Typical applications include legacy industrial control boards, test fixtures, educational embedded platforms, motor and relay control, and repair of equipment originally designed around 40-pin ATmega devices where a socketed DIP package simplifies replacement.
Design consideration: at 8MHz this grade requires VCC of 4.5V to 5.5V; the pin-compatible ATMEGA32-16PU offers a 16MHz speed upgrade in the identical DIP-40 footprint if performance headroom is needed.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA323-8PI 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 ATMEGA323-8PI (same form factor and footprint) β differing in Package, ADC, Debug Interface, Operating Temperature, Throughput.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA32-16PI
β Drop-Inβ In Stock
$2.75 / Unit
View Datasheet βATMEGA32-16PU
β Drop-Inβ In Stock
$3.68 / Unit
View Datasheet βATMEGA323-16PI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA323-8PU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA32A-PU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA323-8PI Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Speed | 8 MHz |
| Flash Memory Size | 32KB (16K x 16) |
| SRAM Size | 2KB |
| EEPROM Size | 1KB |
| Instructions | 131 instructions, most single-cycle |
| Max Throughput | 8 MIPS at 8 MHz (16 MIPS at 16 MHz architecture max) |
| Supply Voltage (VCC) | 4.5 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial, I suffix) |
| Package | 40-PDIP (0.600 in, 15.24mm) |
| Mounting Type | Through Hole |
| ADC | 8-channel, 10-bit |
| Serial Interfaces | USART, SPI, TWI (I2C-compatible) |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Debug Interface | JTAG (on-chip debug and boundary scan) |
| In-System Programming | Yes, via SPI and boot section Flash |
ATMEGA323-8PI Pin Configuration
| Pin 1 | PB0 (XCK/T0) β Port B bit 0 / USART external clock / Timer0 external clock |
| Pin 2 | PB1 (T1) β Port B bit 1 / Timer1 external clock |
| Pin 3 | PB2 (AIN0/INT2) β Port B bit 2 / analog comparator positive input / external interrupt 2 |
| Pin 4 | PB3 (AIN1/OC0) β Port B bit 3 / analog comparator negative input / Timer0 output compare PWM |
| Pin 5 | PB4 (SS) β Port B bit 4 / SPI slave select |
| Pin 6 | PB5 (MOSI) β Port B bit 5 / SPI master output slave input (also ISP data) |
| Pin 7 | PB6 (MISO) β Port B bit 6 / SPI master input slave output (also ISP data) |
| Pin 8 | PB7 (SCK) β Port B bit 7 / SPI serial clock (also ISP clock) |
| Pin 9 | RESET β Active-low reset input / ISP entry |
| Pin 10 | VCC β Digital supply voltage (4.5V to 5.5V) |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL1 β Inverting oscillator amplifier input / internal clock input |
| Pin 13 | XTAL2 β Inverting oscillator amplifier output |
| Pin 14 | PD0 (RXD) β Port D bit 0 / USART receive input |
| Pin 15 | PD1 (TXD) β Port D bit 1 / USART transmit output |
| Pin 16 | PD2 (INT0) β Port D bit 2 / external interrupt 0 |
| Pin 17 | PD3 (INT1) β Port D bit 3 / external interrupt 1 |
| Pin 18 | PD4 (OC1B) β Port D bit 4 / Timer1 output compare B PWM |
| Pin 19 | PD5 (OC1A) β Port D bit 5 / Timer1 output compare A PWM |
| Pin 20 | PD6 (ICP1) β Port D bit 6 / Timer1 input capture |
| Pin 21 | PD7 (OC2) β Port D bit 7 / Timer2 output compare PWM |
| Pin 22 | PC0 (SCL) β Port C bit 0 / TWI serial clock (also JTAG TCK) |
| Pin 23 | PC1 (SDA) β Port C bit 1 / TWI serial data (also JTAG TMS) |
| Pin 24 | PC2 (TCK) β Port C bit 2 / JTAG test clock |
| Pin 25 | PC3 (TMS) β Port C bit 3 / JTAG test mode select |
| Pin 26 | PC4 (TDO) β Port C bit 4 / JTAG test data output |
| Pin 27 | PC5 (TDI) β Port C bit 5 / JTAG test data input |
| Pin 28 | PC6 (TOSC1) β Port C bit 6 / Timer2 oscillator input |
| Pin 29 | PC7 (TOSC2) β Port C bit 7 / Timer2 oscillator output |
| Pin 30 | AVCC β ADC supply voltage |
| Pin 31 | GND β Ground (ADC ground reference) |
| Pin 32 | AREF β ADC analog reference voltage |
| Pin 33 | PA0 (ADC0) β Port A bit 0 / ADC channel 0 |
| Pin 34 | PA1 (ADC1) β Port A bit 1 / ADC channel 1 |
| Pin 35 | PA2 (ADC2) β Port A bit 2 / ADC channel 2 |
| Pin 36 | PA3 (ADC3) β Port A bit 3 / ADC channel 3 |
| Pin 37 | PA4 (ADC4) β Port A bit 4 / ADC channel 4 |
| Pin 38 | PA5 (ADC5) β Port A bit 5 / ADC channel 5 |
| Pin 39 | PA6 (ADC6) β Port A bit 6 / ADC channel 6 |
| Pin 40 | PA7 (ADC7) β Port A bit 7 / ADC channel 7 |
Typical Applications
ATMEGA323-8PI is suitable for 6 applications: Legacy Industrial Control Boards, Embedded Test Fixtures and Instruments, Educational and Training Platforms, Motor and Relay Control Systems, Data Loggers with EEPROM Storage, Equipment Repair and BOM Shortage Mitigation.
Legacy Industrial Control Boards
The ATMEGA323-8PI fits maintenance and repair of industrial controllers originally designed around 40-pin ATmega devices, where its -40C to +85C industrial rating and 4.5V to 5.5V supply tolerate noisy 5V factory power rails. With 32KB Flash and 2KB SRAM it runs typical PLC-adjacent firmware, relay sequencing, and Modus-over-USART communication without external memory. The socketed DIP-40 package allows field replacement without soldering, minimizing production downtime. Designers maintaining such fleets should stock the pin-compatible ATMEGA32-16PI as a 16MHz forward-compatible spare, since the ATmega323 is end-of-life and remaining distributor stock is finite.
Recommended
Embedded Test Fixtures and Instruments
Bench instruments and production test fixtures benefit from the ATMEGA323-8PI's JTAG on-chip debug, which permits boundary-scan and source-level debugging of the fixture firmware itself - a capability the popular ATmega328P lacks. The 8-channel 10-bit ADC acquires pass/fail analog measurements, while SPI and TWI interfaces drive relays, DACs, and displays. At 8MHz and 4.5V to 5.5V it delivers 8 MIPS, sufficient for fixture sequencing and serial reporting over USART. The through-hole DIP-40 package tolerates repeated rework cycles common in lab environments, making it a pragmatic choice for tooling rather than high-volume products.
Recommended
Educational and Training Platforms
Universities and bootcamps use the ATmega323 in embedded-systems courses because the through-hole DIP-40 package can be inserted into breadboards and sockets, letting students wire peripherals directly. The 131-instruction AVR RISC core with mostly single-cycle execution teaches real-time behavior transparently, and free avr-gcc/AVRDUDE toolchains remove licensing cost. The 32KB Flash accommodates substantial lab projects including USART terminals, SPI sensor reads on the 10-bit ADC, and TWI bus experiments. Because classroom use rarely extends beyond 0C to +70C, the commercial ATMEGA32-16PU works equally well and doubles the clock speed for timing experiments.
Recommended
Motor and Relay Control Systems
The ATMEGA323-8PI drives DC motors and relay banks through its two 8-bit timers and one 16-bit timer, which generate PWM via the OC0, OC1A, and OC1B output-compare pins. Operating at 5V with industrial temperature range, it tolerates actuator-heavy enclosures, while brown-out detection and the watchdog timer keep firmware deterministic during power dips from inductive load switching. The 1KB EEPROM stores calibration constants such as PID gains across power cycles. Its three external interrupt-capable pins (INT0, INT1, INT2) accept encoder and limit-switch feedback, and the DIP-40 footprint eases gate-driver wiring in one-off industrial machinery upgrades.
Recommended
Data Loggers with EEPROM Storage
The ATMEGA323-8PI's 1KB EEPROM retains logged parameters through power loss, while the 8-channel 10-bit ADC digitizes up to eight sensor inputs such as temperature, pressure, or level transmitters. USART communication exports records to a PC or GSM modem, and the TWI interface can add external I2C EEPROM or RTC chips for larger history buffers. At 8MHz the core completes sampling, scaling, and store cycles comfortably at kilohertz rates. For cold-chain or outdoor installations, the -40C to +85C industrial rating of the I-suffix part is essential; substitute the ATMEGA32-16PI for active production to secure long-term sourcing.
Recommended
Equipment Repair and BOM Shortage Mitigation
Repair shops and contract manufacturers use the ATMEGA323-8PI to service discontinued equipment whose firmware was compiled for the ATmega323 register map, avoiding a costly firmware port. Because the part ships in a socket-friendly DIP-40 package, swap-in replacement takes minutes. Where stock runs dry, the pin-compatible ATMEGA32-16PI and ATMEGA32-16PU accept the same socket; firmware typically relinks against ATmega32 headers with peripheral verification. Purchasers should qualify at least two distributors (DigiKey, Ampheo, Hotenda) given EOL status, and verify date codes to mitigate counterfeit risk common with legacy microcontrollers.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA323-8PI β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA32-16PI | ATMEGA32-16PU | ATMEGA323-16PI | ATMEGA323-8PU | ATMEGA32A-PU |
|---|---|---|---|---|---|---|
| Package | 40-PDIP (0.600 in, 15.24mm) | 40-PDIP (0.600 in) - same | 40-PDIP (0.600 in) - same | 40-PDIP (0.600 in) - same | 40-PDIP (0.600 in) - same | 40-PDIP (0.600 in) - same |
| Brand | Microchip Technology (originally Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Speed | 8 MHz | 16 MHz | 16 MHz | 16 MHz | 8 MHz | 16 MHz |
| Flash Memory | 32KB (16K x 16) | 32KB | 32KB | 32KB | 32KB | 32KB |
| SRAM | 2KB | 2KB | 2KB | 2KB | 2KB | 2KB |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | 0C to +70C (Commercial) | -40C to +85C | 0C to +70C (Commercial) | 0C to +70C (Commercial) |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Lifecycle Status | EOL | Active | Active | EOL | EOL | Active |
Key Differentiators
- JTAG on-chip debug capability (vs ATmega328P-family DIP parts)
- Industrial temperature grade at 8MHz DIP (vs ATMEGA32-16PU)
- Lower clock grade vs same-die 16MHz variants (vs ATMEGA323-16PI)
Design Notes
The ATMEGA323-8PI requires 4.5V to 5.5V at 8MHz; never operate this speed grade below 4.5V or core timing will be out of spec. Decouple VCC (pin 10) and AVCC (pin 30) with 100nF ceramic capacitors placed within 5mm of each pin, plus a 10uF bulk capacitor. AVCC should connect to VCC through a low-pass LC network when ADC accuracy matters, keeping AVCC ripple below 1 LSB of the 10-bit ADC (approximately 5mV on a 5V reference).
Fuse misconfiguration is the top failure mode when programming this device over ISP: clearing the SPIEN fuse permanently disables serial programming, and selecting an external crystal option without a crystal present bricks the board until a parallel high-voltage programmer is used. Always set fuses through AVRDUDE with verified values, and confirm the CKOPT and clock-source fuses match your 8MHz crystal circuit before locking the LB lock bits.
Because the DIP-40 package is through-hole and often socketed, minimize lead inductance effects by keeping the crystal (XTAL1/XTAL2, pins 12-13) within 15mm of the device with load capacitors grounded close by. Route the JTAG port (PC2-PC5, pins 24-27) to a 2x5 header if in-circuit debugging is planned; note that enabling JTAG consumes four Port C pins, so design the I/O map accordingly or disable JTAG via the JTD bit in software.
Compliance Information
The ATMEGA323 predates wide RoHS certification rollout and original Atmel production was lead-finish (non-Pb) for the PI suffix in early revisions; compliance status is not stated in the provided web data and should be confirmed with the distributor before export-controlled or EU-market production use.
