Glossary¶
This glossary defines key terms used throughout the textbook.
You can link to any term using standard Markdown linking.
ADC (Analog-to-Digital Converter)¶
A module that converts real-world analog voltages into digital values that a microcontroller can process.
ACK / NACK¶
Signals used in I2C communication. ACK (Acknowledge) confirms successful data receipt; NACK (Not Acknowledge) denies it.
Addressing Mode¶
A method of specifying how and where to access data in assembly instructions (e.g., immediate, direct, indirect).
Assembly Language¶
A low-level programming language that provides direct control of the hardware using symbolic instructions.
Baud Rate¶
The number of bits transmitted per second in a serial communication protocol such as UART.
BNE (Branch if Not Equal)¶
A conditional branch instruction that causes program flow to jump if the zero flag is not set.
BRA (Branch Always)¶
An unconditional branch instruction used to jump to a labeled section of code.
Call Stack¶
A memory structure that stores return addresses and local variables when subroutines are called.
CALL¶
An instruction used to invoke a subroutine or function.
Compare (CP)¶
An instruction that subtracts one value from another and sets flags based on the result — used before conditional branches.
DAC (Digital-to-Analog Converter)¶
A peripheral that converts digital values into analog voltage. (Mentioned as a conceptual opposite to ADC.)
Debouncing¶
The process of filtering out signal noise or bouncing, especially for buttons or mechanical switches.
DEC / INC¶
Decrement or Increment – arithmetic instructions used to subtract or add 1 to a register.
Flag (Condition Code)¶
A single-bit status indicator (e.g., Z for zero, C for carry, N for negative) used for conditional branching in assembly.
Firmware¶
The permanent software programmed into the microcontroller's Flash memory.
Frame Pointer (W14)¶
A register that helps reference variables in stack frames during function calls.
GOTO¶
An instruction that jumps to a specific labeled location in code.
Immediate Value¶
A constant literal used directly in an instruction, usually prefixed with # (e.g., #10).
Interrupt¶
A signal that temporarily halts the normal program flow to run a special function called an Interrupt Service Routine (ISR).
ISR (Interrupt Service Routine)¶
A function that runs automatically in response to an interrupt and returns control to the main program afterward.
I2C (Inter-Integrated Circuit)¶
A two-wire serial communication protocol supporting multiple devices using addressing and shared lines.
Microcontroller¶
A compact integrated circuit that includes a CPU, memory, and peripherals for real-time control of embedded systems.
MPLAB X IDE¶
Microchip’s official development environment for programming PIC microcontrollers.
NOP¶
An instruction that does nothing for one instruction cycle. Useful for breakpoints and timing.
Operand¶
A value or register used in an assembly instruction (e.g., source or destination in a MOV instruction).
Opcode¶
The operation code in assembly language that tells the processor what action to perform (e.g., MOV, ADD).
Output Compare¶
A peripheral that compares a timer value to a preset and triggers an event — often used for PWM generation.
PIC24FJ64GA002¶
The 16-bit microcontroller used in this textbook, produced by Microchip, featuring timers, ADCs, UART, and more.
Polling¶
A method where the CPU continuously checks a condition (e.g., a flag or register), instead of responding to interrupts.
PPS (Peripheral Pin Select)¶
A Microchip feature that allows flexible assignment of internal peripheral inputs/outputs to physical pins.
Prescaler¶
A divider that reduces the clock frequency input to a timer, allowing for longer timing intervals.
PRx (Period Register)¶
Register used to define the match/reset value of a timer, controlling when it overflows or triggers an interrupt.
Prompt¶
A short, scenario-based coding challenge intended to help students apply concepts through practice.
PWM (Pulse-Width Modulation)¶
A method for simulating analog output using digital pulses of variable duty cycle — used in motor control, dimming, etc.
Register (W0–W15)¶
A small, fast-access memory location in the CPU used to hold data during computation.
RET¶
An instruction that returns from a subroutine by restoring the last return address from the stack.
Stack¶
A last-in, first-out (LIFO) memory structure used for storing return addresses and function call data.
Stack Pointer (W15)¶
A special-purpose register that always points to the top of the call stack.
Subroutine¶
A reusable block of code (a function) that can be called from multiple places in the program.
Timer¶
A peripheral that counts clock cycles and can generate interrupts when it matches a preset value.
UART (Universal Asynchronous Receiver/Transmitter)¶
A hardware module for asynchronous serial communication using TX/RX lines.
Watchdog Timer (WDT)¶
A system-reset timer that triggers a reset if the program stops running or hangs unexpectedly.
Working Register¶
One of 16 fast-access registers (W0–W15) used for computation, memory access, and control flow.
XOR¶
A bitwise logic operation that outputs true when inputs differ — often used for toggling values.