Microchip PIC16F84-10I/SO: An Overview of the 8-Bit CMOS EEPROM Microcontroller
The Microchip PIC16F84-10I/SO remains a historically significant and widely recognized component in the world of embedded systems. As an 8-bit CMOS EEPROM-based microcontroller, it helped democratize electronics design, offering a blend of reprogrammability, ease of use, and reliability that made it a favorite among hobbyists, students, and professionals for decades.
Housed in a compact 18-pin SOIC (Small Outline Integrated Circuit) package, the ‘SO’ in its designation, this microcontroller is designed for space-constrained applications. The ‘-10’ denotes its capability to operate at a maximum clock frequency of 10 MHz, enabling the execution of instructions at a swift 1.25 million instructions per second (MIPS).
A defining feature of the PIC16F84 is its non-volatile EEPROM memory technology. Unlike OTP (One-Time Programmable) or early EPROM variants that required UV light for erasure, this microcontroller can be electrically erased and reprogrammed. This allows for rapid prototyping, in-field firmware updates, and endless debugging cycles without discarding the chip. Its memory architecture includes:
1K x 14 words of Flash Program Memory
68 bytes of RAM
64 bytes of EEPROM Data Memory for storing critical variables that must persist after power loss.
The device features a simple yet powerful RISC (Reduced Instruction Set Computing) architecture with only 35 single-word instructions to learn. This simplicity makes it an excellent educational tool for understanding microcontroller fundamentals. Its I/O capabilities are managed through two bidirectional ports: Port A (5 bits) and Port B (8 bits). Each pin can be individually configured as an input or output, providing direct interface capabilities with sensors, LEDs, buttons, and other peripherals.
Additional integrated features solidify its utility. An external interrupt pin (RB0/INT) allows the microcontroller to respond immediately to critical external events. The Timer0 module with an 8-bit pre-scaler is essential for creating precise timing intervals and counting events. A unique feature for a microcontroller of its era is the watchdog timer (WDT), which acts as a dedicated internal timer that, if not cleared periodically, resets the device. This is a crucial mechanism for recovering from software malfunctions and ensuring system reliability in unsupervised applications.
Operating from a wide voltage range of 2.0V to 5.5V, the PIC16F84-10I/SO is suited for both battery-powered and mains-connected devices. Its low power consumption in CMOS technology further enhances its suitability for portable applications.
While newer microcontrollers offer more memory, higher performance, and advanced peripherals (like USB, CAN, or Ethernet), the PIC16F84’s legacy is its role in introducing a generation to the world of programmable control. It demonstrated that powerful embedded solutions could be accessible and affordable.
ICGOODFIND: The PIC16F84-10I/SO is a classic, EEPROM-based microcontroller renowned for its reprogrammability, simple RISC architecture, and robust I/O control. It serves as a foundational pillar for learning embedded systems and remains a viable solution for simple control tasks, DIY projects, and applications where extreme processing power is not required.
Keywords: 8-bit Microcontroller, CMOS Technology, EEPROM Memory, RISC Architecture, Watchdog Timer.
