PIC18F2321-I/SP - 8-Bit 40MHz 8KB Flash MCU | Microchip 28-SPDIP
MPN: PIC18F2321-I/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.07 | $7.07 |
| 10 | $6.4 | $64.00 |
| 100 | $5.5 | $550.00 |
| 500 | $4.85 | $2,425.00 |
| 1,000 | $4.2 | $4,200.00 |
PIC18F2321-I/SP Overview
What is a PIC18F microcontroller? The PIC18F family is Microchip's high-performance 8-bit microcontroller line based on an enhanced RISC architecture with 16-bit instructions and an 8-bit data path. PIC18F parts use Harvard architecture, support C-compiler-friendly development, and provide peripherals such as A/D converters, PWM, comparators, and configurable serial ports (SPI/I2C). Within the broader taxonomy, PIC18F MCUs sit between baseline PIC10/12/16 and 16-bit PIC24/dsPIC families, making them well suited for mid-complexity real-time control.
Key features of the PIC18F2321-I/SP include a 10-bit A/D converter with up to 10 channels, two analog comparators, two capture/compare/PWM (CCP) modules, a synchronous serial port configurable as SPI or I²C, and nanoWatt Technology power management for low-power applications. The device operates from 4.2 V to 5.5 V and supports an industrial temperature range of -40 °C to +85 °C as denoted by the "I" suffix. With 25 I/O pins and an enhanced instruction set of 77 single-word instructions, the part targets applications requiring deterministic real-time response.
Architecturally, the PIC18F2321 uses an 8-bit data path with a 16-bit instruction set, allowing 10 MIPS throughput at 40 MHz CPU clock. Internal oscillator options, a programmable brown-out reset, and a low-power sleep mode further support battery-powered designs. The combination of on-chip EEPROM, flexible peripherals, and the established MPLAB development ecosystem enables rapid prototyping and production scaling.
Typical applications include industrial control systems, sensor interface modules, low-power remote sensing nodes, consumer appliance controls, and small motor/lighting controllers. The 28-SPDIP package is preferred for prototyping, breadboarding, and legacy designs where through-hole assembly is required or where mechanical robustness matters.
When designing with the PIC18F2321-I/SP, ensure that your supply decoupling (0.1 µF + 10 µF) is placed close to VDD/AVDD/VSS/AVSS, and configure the configuration bits (oscillator, watchdog, brown-out, code protection) appropriately using MPLAB X IDE.
This page synthesizes distributor pricing, drop-in alternatives, application use cases, and practical design notes not typically collected on a single manufacturer datasheet page.
Drop-in alternatives for PIC18F2321-I/SP — 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 PIC18F2321-I/SP (same form factor and footprint) — differing in Architecture, Comparators, Data SRAM, Mounting Type, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2221-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2321-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2321T-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2321-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2321-E/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4321-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2321-I/SP Maximum Ratings & Electrical Characteristics
| Product Family | PIC18F |
| Core | 8-bit RISC (enhanced) |
| Architecture | Harvard |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Instruction Execution Time | 100 ns (10 MIPS) |
| Program Memory (Flash) | 8 KB (4K x 16 words) |
| Data SRAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Operating Temperature | -40 °C to +85 °C (industrial, "I" suffix) |
| I/O Pins | 25 |
| A/D Converter | 10-bit, up to 10 channels |
| Comparators | 2 |
| CCP Modules | 2 |
| Serial Peripherals | 1x SPI / I²C (MSSP) |
| Timers | 8-bit and 16-bit (per datasheet) |
| Package | 28-pin SPDIP ("SP") |
| Mounting Type | Through-Hole (THT) |
| RoHS Status | Compliant |
| Instruction Set Size | 77 single-word instructions |
| Low-Power Feature | nanoWatt Technology |
| Brown-Out Reset | Yes (programmable) |
| ICSP / In-Circuit Debug | Yes (ICD) |
| Self-Programming | Yes (Flash) |
PIC18F2321-I/SP Pin Configuration
| Pin 1 | MCLR/RE3 — Master Clear (reset) input or digital input only on RE3 |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / A/D VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / A/D VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI slave select |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / clock output |
| Pin 11 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 |
| Pin 14 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I²C clock |
| Pin 15 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I²C data |
| Pin 16 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT0 — PORTB bit 0 / External interrupt 0 |
| Pin 22 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 23 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 24 | RB3/CCP2 — PORTB bit 3 / CCP2 (alternate) |
| Pin 25 | RB4 — PORTB bit 4 |
| Pin 26 | RB5/PGM — PORTB bit 5 / LVP programming |
| Pin 27 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 28 | RB7/PGD — PORTB bit 7 / ICSP data |
Typical Applications
PIC18F2321-I/SP is suitable for 6 applications: Industrial Sensor Interface Module, Consumer Appliance Control Board, Small DC Motor and PWM Driver, Battery-Backed Sensor Logger, Educational and Hobbyist Projects, Building Automation Lighting Controller.
Industrial Sensor Interface Module
The PIC18F2321-I/SP is well suited for industrial sensor interface modules that aggregate signals from temperature, pressure, or flow sensors into a Modbus or analog output. Its 10-channel 10-bit A/D converter (with up to 25 I/O pins) allows direct connection to multiple analog sensors without an external multiplexer, while the 8 KB Flash comfortably hosts Modbus RTU state machines and calibration routines. Operating from 4.2-5.5 V, it interfaces directly with 5V-powered industrial 4-20 mA loops. The 28-SPDIP package supports through-hole assembly in rugged enclosures where mechanical robustness matters. With nanoWatt Technology sleep currents below typical MCU classes, the part is suitable for line-powered installations where continuous operation is required but standby efficiency still contributes to system thermal budget.
Recommended
Consumer Appliance Control Board
In consumer appliances such as washing machines, dishwashers, or microwave ovens, the PIC18F2321-I/SP serves as the main control MCU. The 10 MIPS throughput is more than adequate for motor control loops, button matrix scanning, and user interface driving through the 2 CCP modules. The internal EEPROM (256 B) reliably stores user preferences and cycle counters across power cycles, while 8 KB of Flash accommodates state-machine firmware. Operating up to +85 °C, the part is suitable for enclosures near heating elements. The enhanced 8-bit architecture and 16-bit instructions mean firmware can be efficiently written in C using MPLAB XC8, enabling rapid design cycles for high-volume product lines.
Recommended
Small DC Motor and PWM Driver
The PIC18F2321-I/SP can drive small brushed DC motors, solenoids, and LED dimming circuits using its two CCP modules for PWM generation and a configurable MSSP for SPI/I²C feedback. The 40 MHz CPU clock supports up to 10 MIPS, enabling high-resolution PWM at low audible frequencies to avoid motor whine. The 25 I/O lines allow direct connection to H-bridge drivers such as the TC4427 or VNH2SP30 without external glue logic. The part's industrial temperature range is sufficient for enclosed motor housings where temperatures can reach +70 °C to +85 °C. With self-programming Flash, the same MCU can store application presets and allow field firmware upgrades via UART bootloader.
Recommended
Battery-Backed Sensor Logger
For battery-backed sensor logging applications, the PIC18F2321-I/SP's nanoWatt Technology feature enables low standby current. While the standard PIC18F2321-I/SP operates from 4.2-5.5 V, designers targeting low-voltage battery operation can drop in the pin-compatible PIC18LF2321-I/SP variant for 2.0-3.3 V operation. The 256-byte EEPROM is ideal for storing calibration tables and timestamps without external FRAM, while the A/D converter samples sensors like thermistors or photodiodes. With sleep modes drawing microamps, the system can run for extended periods on a single CR2032 cell when paired with the right wake-up strategy. UART, SPI, and I²C peripherals support external radio modules for periodic telemetry.
Recommended
Educational and Hobbyist Projects
The PIC18F2321-I/SP is widely used in university embedded systems courses and hobbyist projects because of its through-hole 28-SPDIP form factor that fits standard breadboards and IC sockets. The PICkit 3 or PICkit 4 in-circuit debugger plugs directly into the ICSP pins for instant programming and debug, supporting iterative learning. The 8 KB Flash, 512 B RAM, and 25 I/O provide enough capability to teach C programming, interrupt handling, A/D conversion, and serial communication concepts in a single semester. Sample code, application notes, and a large open-source community around MPLAB X IDE accelerate time-to-first-prototype for students and makers.
Recommended
Building Automation Lighting Controller
In building automation systems, the PIC18F2321-I/SP can act as a zone-level lighting or HVAC controller. The two CCP modules generate PWM outputs for dimmable LED drivers, while the MSSP communicates with digital sensors and wall-mounted keypads via I²C. With 8 KB of Flash, the firmware can support DALI-like lighting protocols, schedule storage, and override logic. The 25 I/O pins handle multiple relay outputs for fan coils or contactors. Industrial temperature rating makes the part suitable for above-ceiling installations where ambient may reach +70 °C. The 28-SPDIP package is preferred for serviceable installations where through-hole parts are easier to replace than fine-pitch SMD.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2321-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2221-I/SP | PIC18LF2321-I/SP | PIC18F2321-E/SP |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SPDIP | 28-SPDIP (same) | 28-SPDIP (same) | 28-SPDIP (same) |
| Program Flash | 8 KB | 4 KB (-50%) | 8 KB (same) | 8 KB (same) |
| SRAM | 512 bytes | 512 bytes (same) | 512 bytes (same) | 512 bytes (same) |
| Data EEPROM | 256 bytes | 256 bytes (same) | 256 bytes (same) | 256 bytes (same) |
| Maximum CPU Speed | 40 MHz (10 MIPS) | 40 MHz (same) | 40 MHz (same) | 40 MHz (same) |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V (same) | 2.0 V to 5.5 V (extended low-V) | 4.2 V to 5.5 V (same) |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C (same) | -40 °C to +85 °C (same) | -40 °C to +125 °C (extended) |
| A/D Channels | 10 x 10-bit | 10 x 10-bit (same) | 10 x 10-bit (same) | 10 x 10-bit (same) |
| I/O Pins | 25 | 25 (same) | 25 (same) | 25 (same) |
Key Differentiators
- Pin-compatible PIC18LF2321 variant for low-voltage battery operation (vs PIC18LF2321-I/SP)
- Higher Flash density than PIC18F2221 (vs PIC18F2221-I/SP)
- Industrial temperature range vs commercial grades (vs PIC18F2321-E/SP)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor as close as possible to the VDD pin (pin 20), with a bulk 10 µF tantalum or aluminum capacitor at the board entry. The PIC18F2321-I/SP will draw peak currents during A/D conversion and Flash programming; insufficient decoupling causes code-execution glitches. For A/D accuracy, also decouple AVdd separately if the application demands high-resolution analog measurements.
Always configure the CONFIG registers (oscillator, watchdog, brown-out reset, code protection, low-voltage programming) before any meaningful firmware runs. Using MPLAB XC8's #pragma config directives is the recommended way. A common pitfall is leaving the watchdog timer enabled with the default long timeout, causing unexpected resets in slow background loops. Use the WDTCPS macros carefully.
Keep the crystal or external clock traces short and surround them with a ground pour. The 28-SPDIP package places OSC1 (pin 9) and OSC2 (pin 10) close to the corner; route the crystal to the IC with minimal trace length. Avoid routing noisy signals (PWM, motor drivers) directly under the crystal area to prevent jitter.
Estimated: at 40 MHz with all peripherals active, the PIC18F2321-I/SP typically draws ~15 mA from a 5 V supply, yielding ~75 mW dissipation. This is well within the SPDIP thermal envelope (theta_JA ~70 °C/W). No external heatsinking is required; ensure ambient temperature stays below +85 °C for the industrial-grade I variant.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade; not AEC-Q100 qualified (choose AEC-Q100 variants for automotive).
