HC05PL

HC05PL Technical Summary

Overview

The HC05PL is a versatile microcontroller unit (MCU) from Motorola's HC05 family, designed for embedded control applications. It integrates a robust 8-bit CPU core with on-chip memory, I/O ports, and peripheral features. The device is well-suited for applications requiring low-power operation, real-time control, and interfacing with external components. Its architecture includes ROM, RAM, and configurable I/O pins, making it adaptable to a wide range of embedded systems.

Features

• 8-bit HC05 CPU Core: Efficient processing with a rich instruction set.
• On-Chip Memory: Includes ROM for program storage and RAM for data handling.
• Configurable I/O Ports: Multiple bidirectional I/O pins with alternate functions.
• Interrupt Support: Hardware and software interrupt capabilities for real-time event handling.
• Watchdog Timer (COP): Enhances system reliability by detecting software malfunctions.
• Oscillator Options: Supports external crystal or resonator for clock generation.
• Low-Power Modes: Includes power-saving features for energy-efficient operation.

Applications

The HC05PL is ideal for a variety of embedded control applications, including:

• Consumer electronics (remote controls, toys, small appliances).
• Industrial automation (sensors, actuators, control panels).
• Automotive systems (dashboard controls, basic monitoring).
• Communication devices (DTMF generation, simple modems).
• Home automation (lighting control, security systems).

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_DD): -0.3V to +7.0V
• Input Voltage (V_IN): -0.3V to V_DD + 0.3V
• Operating Temperature: -40°C to +85°C
• Storage Temperature: -55°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_DD): 3.0V to 5.5V
• Clock Frequency: Up to 4 MHz (dependent on V_DD)
• Input High Voltage (V_IH): 0.7 × V_DD (min)
• Input Low Voltage (V_IL): 0.3 × V_DD (max)

Pin Descriptions

Power and Ground

• V_DD: Primary power supply pin (+3V to +5.5V).
• V_SS: Ground reference pin.

Clock and Reset

• OSC1, OSC2: External crystal or resonator connection pins.
• RESET: Active-low reset input for initializing the MCU.

General-Purpose I/O and Special Function Pins

• LED/IRQ: Dual-function pin for LED control or external interrupt.
• PA0-PA6: Port A pins with alternate functions (DTMF, timer capture/comparison).
• PB0-PB7: Port B pins with keyboard interrupt (KBI) support on PB0-PB3.
• PC0-PC7: Port C pins, general-purpose I/O.

Memory Organization

Memory Map

• ROM: 4 KB for firmware storage (address range: 0x0000–0x0FFF).
• RAM: 176 bytes for data storage (address range: 0x0040–0x00EF).
• I/O Registers: Mapped at 0x0000–0x003F for peripheral control.

Watchdog Timer (COP)

The COP watchdog register (COPR) provides a system reset mechanism if the software fails to refresh the timer within a specified period, ensuring fault recovery.

Central Processing Unit (CPU)

Registers

• Accumulator (A): 8-bit register for arithmetic and logic operations.
• Index Register (X): Used for indexed addressing modes.
• Stack Pointer (SP): Manages the subroutine call/return stack.
• Program Counter (PC): 16-bit register tracking the next instruction address.
• Condition Code Register (CCR): Contains status flags (H, I, N, Z, C).

Condition Code Flags

• Half Carry (H): Indicates a carry between lower nibbles in arithmetic operations.
• Interrupt Mask (I): Globally enables/disables interrupts.
• Negative (N): Set if the result of an operation is negative.
• Zero (Z): Set if the result of an operation is zero.
• Carry/Borrow (C): Indicates carry/borrow in arithmetic operations.

Interrupt System

Interrupt Vectors

The HC05PL supports multiple interrupt sources, each with a fixed vector address in ROM:

• Reset vector (0x1FFE–0x1FFF).
• Software interrupt (SWI) vector (0x1FFC–0x1FFD).
• External interrupt (IRQ) vector (0x1FFA–0x1FFB).

Interrupt Processing

When an interrupt occurs, the CPU saves the current context (PC, CCR, and registers) to the stack and jumps to the corresponding vector address. The interrupt service routine (ISR) must clear the interrupt source before returning.

Package Information

The HC05PL is available in a 28-pin dual in-line package (DIP) or surface-mount (SOIC) package. Key dimensions:

• DIP-28: 36.32 mm × 10.16 mm (max).
• SOIC-28: 17.9 mm × 7.5 mm (max).

Pinout Diagram

The pin assignments are as follows (simplified):

• Pins 1–4: V_SS, OSC1, OSC2, RESET.
• Pins 5–12: Port A (PA0–PA6) and LED/IRQ.
• Pins 13–20: Port B (PB0–PB7).
• Pins 21–28: Port C (PC0–PC7) and V_DD.

Conclusion

The HC05PL is a flexible and cost-effective MCU for embedded applications requiring moderate processing power and I/O capabilities. Its integrated peripherals, low-power modes, and robust interrupt system make it suitable for diverse control tasks. Designers can leverage its memory-mapped I/O and versatile pin