Absolute Section

A section with a fixed (absolute) address which can not be changed by the linker.

Access RAM (PIC18CXXX Devices Only)

This is a region of data memory RAM that can be accessed regardless of the currently selected bank. This allows special function registers to be accessed by the instruction without changing the currently selected bank. Access RAM also contains some General Purpose Registers (GPRs). This is useful for the saving of required variables during context switching (such as during an interrupt).
When used in reference to PIC18CXXX devices, Access RAM refers to special general purpose registers that allow access regardless of the setting of the bank select bit (BSR).

Acquisition Time (TACQ)

This is related to Analog to Digital (A/D) converters. This is the time that the PIC18CXXX A/D's holding capacitor acquires the analog input voltage level connected to it. When the GO bit is set, the analog input is disconnected from the holding capacitor and the A/D conversion is started.

A/D

Refers to Analog-to-Digital Converter. See description under ""Analog to Digital (A/D)"".

ALU

Arithmetical Logical Unit. Device logic that is responsible for the mathematical (add, subtract, ...), logical (and, or, ...), and shifting operation.

Analog

Refers to electronic transmission accomplished by adding signals of varying frequency or amplitude to carrier waves of a given frequency of alternating

Analog to Digital (A/D)

The conversion of an analog input voltage to a ratiometric digital equivalent value.

Assembly Language

A symbolic language that describes the binary machine code in a readable form.

AUSART

Addressable Universal Synchronous Asynchronous Receiver Transmitter. This module can either operate as a full duplex asynchronous communications port, or a half duplex synchronous communications port. When operating in the asynchronous mode, the USART can be interfaced to a PC's serial port.

Alphanumeric

Alphanumeric characters include alpha characters and numbers: (0,1, …, 9).

Application

A set of software and hardware developed by the user, usually designed to be a product controlled by a PICmicro microcontroller.

Assemble

What an assembler does. See assembler.

Assembler

A language tool that translates a user's assembly source code (.asm) into machine code. MPASM is Microchip's assembler.

Assembly

A programming language that is once removed from machine language. Machine languages consist entirely of numbers and are almost impossible for humans to read and write. Assembly languages have the same structure and set of commands as machine languages, but they enable a programmer to use names (mnemonics) instead of numbers.

Assigned Section

A section which has been assigned to a target memory block in the linker command file. The linker allocates an assigned section into its specified target memory block.

Bank

This is a method of addressing Data Memory. Since enhanced devices have 8-bits for direct addressing, instructions can address up to 256 bytes. To allow more data memory to be present on a device, data memory is partitioned into contiguous banks of 256 bytes each. To select the desired bank, the bank selection register (BSR) needs to be appropriately configured. 16 banks can be implemented.

Baud

Generally this is how the communication speed of serial ports is described. Equivalent to bits per second (bps).

BCD

See description under ""Binary Coded Decimal (BCD)"".

Binary Coded Decimal (BCD)

Each 4-bit nibble expresses a digit from 0-9. Usually two digits are contained in a byte yielding a range of 0 - 99.

BOR

See description under ""Brown-out Reset (BOR)"".

Brown-out

A condition where the supply voltage of the device temporarily falls below the specified minimum operation point. This can occur when a load is switched on and causes the system/device voltage to drop.

Brown-out Reset (BOR)

Circuitry which will force the device to the RESET state if the device's power supply voltage falls below a specified voltage level. Some devices have an internal BOR circuit, while other devices would require an external circuit to be created.

Bus width

This is the number of bits of information that a bus carries. For the Data Memory, the bus width is 8-bits. For enhanced devices the Program Memory bus width is 16-bits.

Breakpoint - Hardware

An event whose execution will cause a halt.

Breakpoint - Software

An address where execution of the firmware will halt. Usually achieved by a special break
opcode.

Build

A function that recompiles all the source files for an application.

C

A high level programming language that may be used to generate code for PICmicro MCUs, especially high-end device families.

Calibration Memory

A special function register or registers used to hold values for calibration of a PICmicro® microcontroller on-board RC oscillator.

CAN

Controller Area Network. A peripheral interface targeting automotive and industrial applications.

Capture

A function of the CCP module in which the value of a timer/counter is ""captured"" into a holding register module when a predetermined event occurs.

Capture Register

A 16-bit register that is loaded with the value of the 16-bit TMR1 register when a capture event occurs.

CCP

Capture, Compare, Pulse Width Modulation (PWM). The CCP module can be configured to operate as an input capture, or a timer compare, or a PWM output.

COFF

Common Object File Format. An intermediate file format generated by MPLINK that contains machine code and debugging information.

Command Line Interface

Command line interface refers to executing a program on the DOS command line with options. Executing MPASM with any command line options or just the file name will invoke the assembler. In the absence of any command line options, a prompted input interface (shell) will be executed.

Common RAM

This is a region of the data memory RAM that is the same RAM location across all banks. This common RAM may be implemented between addresses 70h - 7Fh (inclusive). This common area is useful for the saving of required variables during context switching (such as during an interrupt).

Compare

A function of the CCP module in which the device will perform an action when a timer's register value matches the value in the compare register.

Compare Register

A 16-bit register that contains a value that is compared to the 16-bit TMR1 register. The compare function triggers when the counter matches the contents of the compare register.

Compile

What a compiler does. See compiler.

Compiler

A language tool that translates a user's C source code into machine code. MPLAB-C17 and MPLAB-C18 are Microchip's C compilers for PIC17CXXX and PIC18CXXX devices, respectively.

Configuration Bits

Unique bits programmed to set PICmicro microcontroller modes of operation. A configuration bit may or may not be preprogrammed. These bits are set in the Options > Development Mode dialog for simulators or emulators and in the _ _ CONFIG MPASM directive for programmers.

Configuration Word

This is a non-volatile memory location that specifies the characteristics that the device will have for operation (such as oscillator mode, WDT enable, start-up timer enables). These characteristics can be specified at the time of device programming. For EPROM memory devices, as long as the bit is a '1', it may at a later time be programmed as a '0'. The device must be erased for a '0' to be returned to a '1'.

Conversion Time (Tconv)

This is related to Analog-to-Digital (A/D) converters. This is the time that the PIC18CXXX A/D's converter requires to convert the analog voltage level on the holding capacitor to a digital value.

CPU

Central Processing Unit. Decodes the instructions, and determines the operands and operations that are needed for program execution. Arithmetic, logical, or shift operations are passed to the ALU.

D/A

See description under ""Digital to Analog"".

DAC

Digital to analog converter.

Data Bus

The bus which is used to transfer data to and from the data memory.

Data EEPROM

Data Electrically Erasable Programmable Read Only Memory. This memory is capable of being programmed and re-programmed by the CPU to ensure that in the case of a power loss, critical values/variables are retained in the non-volatile memory.

Data Memory

The memory that is on the Data Bus. This memory is volatile (SRAM) and contains both the Special Function Registers and General Purpose Registers.

Data Memory

General purpose file registers (GPRs) from RAM on the PICmicro device being emulated. The File Register window displays data memory.

Digital-to-Analog

The conversion of a digital value to an equivalent ratiometric analog voltage.

Direct Addressing

When the Data Memory Address is contained in the Instruction. The execution of this type of instruction will always access the data at the embedded address.

Directives

Directives provide control of the assembler's operation by telling MPASM how to treat mnemonics, define data, and format the listing file. Directives make coding easier and provide custom output according to specific needs.

Download

Download is the process of sending data from the PC host to another device, such as an emulator, programmer or target board.

EEPROM

Electrically Erasable Programmable Read Only Memory. A special type of PROM that can be erased electrically. Data is written or erased one byte at a time. EEPROM retains its contents even when power is turned off.

Embedded System

Special-purpose computer built into and integral to a device. It is used to control, monitor or assist an operation. All embedded systems are or include computers, the simplest being a single microprocessor (""chip""). A microprocessor may be designed so that ROM software (""firmware"") for a particular purpose can be added (e.g., a PC's ROM BIOS). (definition from ChipCenter.com)

Emulation

The process of executing software loaded into emulation memory as if the firmware resided on the microcontroller device under development.

Emulation Memory

Program memory contained within the emulator.

Emulator

Hardware that performs emulation.

Emulator System

The MPLAB®-ICE emulator system includes the pod, processor module, device adapter, cables, and MPLAB® Software. The PICMASTER® emulator system includes the pod, device-specific probe, cables, and MPLAB Software.

EPROM

Electrically Programmable Read Only Memory. This memory has the capability to be programmed in-circuit. Erasing requires that the program memory be exposed to UV light.

Event

A description of a bus cycle which may include address, data, pass count, external input, cycle type (fetch, R/W), and time stamp. Events are used to describe triggers and break points.

Executable Code

See Hex Code.

Export

Send data out of the MPLAB IDE in a standardized format.

Expressions

Expressions are used in the operand field of MPASM's source line and may contain constants, symbols, or any combination of constants and symbols separated by arithmetic operators. Each constant or symbol may be preceded by a plus or minus to indicate a positive or negative expression.

External RAM (PIC17CXXX and PIC18CXXX Devices Only)

Off-chip Read/Write memory.

EXTRC

External Resistor-Capacitor (RC). Some devices have a device oscillator option that allows the clock to come from an external RC. This is the same as RC mode on some devices.

Flash

A type of EEPROM where data is written or erased in blocks instead of bytes.

FLASH Memory

This memory has the capability to be programmed and erased in-circuit. Program Memory technology that is almost functionally equivalent to Program EEPROM Memory.

FOSC

Frequency of the device oscillator.

File Registers

On-chip general purpose and special function registers.

GIO

General Input/Output.

GPIO

General Purpose Input/Output.

GPR

General Purpose Register (RAM). A portion of the data memory that can be used to store the program's dynamic variables.

Harvard Architecture

In this architecture, the Program Memory and Data Memory buses are separated. This allows concurrent accesses to Data Memory and Program Memory, which increases the performance of the device. All PICmicro® devices implement a Harvard Architecture.

Hex Code

Executable instructions assembled or compiled from source code into standard hexadecimal format code. Also called executable or machine code. Hex code is contained in a hex file.

Hex File

An ASCII file containing hexadecimal addresses and values (hex code) suitable for programming a device. This format is readable by a device programmer.

High Level Language

A language for writing programs that is of a higher level of abstraction from the processor than assembler code. High level languages (such as C) employ a compiler to translate statements into machine instructions that the target processor can execute.

Holding Capacitor

This is a capacitor in the Analog-to-Digital (A/D) module which ""holds"" an analog input level once a conversion is started. During acquisition, the holding capacitor is charged/discharged by the voltage level on the analog input pin. Once the conversion is started, the holding capacitor is disconnected from the analog input and ""holds"" this voltage for the A/D conversion.

HS (High Speed)

High Speed. One of the device oscillator modes. The oscillator circuit is tuned to support the high frequency operation. Currently this allows for operation from 4 MHz to 25 MHz.

I2C™

Inter-Integrated Circuit. This is a two wire communication interface. This feature is one of the modes of the ""SSP"" and ""MSSP"" modules.

ICD

In-Circuit Debugger. MPLAB-ICD is Microchip's in-circuit debugger for PIC16F87X devices. MPLAB-ICD works with MPLAB IDE.

ICE

In-Circuit Emulator. MPLAB-ICE is Microchip's in-circuit emulator that works with MPLAB IDE.

IDE

Integrated Development Environment. An application that has multiple functions for firmware development. The MPLAB IDE integrates a compiler, an assembler, a project manager, an editor, a debugger, a simulator, and an assortment of other tools within one Windows application. A user developing an application can write code, compile, debug, and test an application without leaving the MPLAB IDE desktop.

Identifier

A function or variable name.

Import

Bring data into the MPLAB Integrated Development Environment (IDE) from an outside source, such as from a hex file.

Indirect Addressing

When the Data Memory Address is not contained in the Instruction, the instruction operates on the INDF address, which causes the Data Memory Address to be the value in the FSR register. The execution of the instruction will always access the data at the address pointed to by the FSR register.

Initialized Data

Data which is defined with an initial value. In C, int myVar=5; defines a variable which will reside in an initialized data section.

Instruction Bus

The bus which is used to transfer instruction words from the program memory to the CPU.

Instruction Cycle

The events for an instruction to execute. There are four events which can generally be described as: Decode, Read, Execute, and Write. Not all events will be done by all instructions. To see the operations during the instruction cycle, please look at the description of each instruction. Four external clocks (Tosc) make one instruction cycle (TCY).

Instruction Fetch

Due to the Harvard architecture, when one instruction is to be executed, the next location in program memory is ""fetched"" and ready to be decoded as soon as the currently executing instruction is completed.

Interrupt

A signal to the CPU that causes the program flow to be forced to the Interrupt Vector Address (04h in program memory). Before the program flow is changed, the contents of the Program Counter (PC) are forced onto the hardware stack, so that program execution may return to the interrupted point.

INTRC

Internal Resistor-Capacitor (RC). Some devices have a device oscillator option that allows the clock to come from an internal RC combination.

KEELOQ®

KEELOQ® is a patented code-hopping technology. Microchip KEELOQ products provide a method for encrypting data for a unidirectional transmission, where each transmission is unique even if the same button is pressed.

LCD

Liquid Crystal Display. Useful for giving visual status of a system. This may require the specification of custom LCD glass.

LED

Light Emitting Diode. Useful for giving visual status of a system.

Librarian

A language tool that creates and manipulates libraries. MPLIB is Microchip's librarian.

Library

A library is a collection of relocatable object modules. It is created by assembling multiple source files to object files, and then using the librarian to combine the object files into one library file. A library can be linked with object modules and other libraries to create executable code.

LIN Protocol Specification

A low cost, short-distance, low speed network designed to transmit changes in switch settings and respond to switch changes. Used in many automotive subsystems.

Link

What a linker does. See Linker.

Linker

A language tool that combines object files and libraries to create executable code. Linking is performed by Microchip's linker, MPLINK.

Linker Script Files

Linker script files are the command files of MPLINK (.LKR). They define linker options and describe available memory on the target platform.

Literal

This is a constant value that is embedded in an instruction word.

Listing File

A listing file is an ASCII text file that shows the machine code generated for each C source statement, assembly instruction, MPASM directive, or macro encountered in a source file.

Logic Probes

Up to 14 logic probes connected to the emulator. The logic probes provide external trace inputs, trigger output signal, +5V, and a common ground.

Long Word Instruction

An instruction word that embeds all the required information (opcode and data) into a single word. This ensures that every instruction is accessed and executed in a single instruction cycle.

LP

One of the device oscillator modes. Used for low frequency operation which allows the oscillator to be tuned for low power consumption. Operation is up to 200 kHz.

LSb (or LSB)

Least Significant Bit.

Machine cycle

This is a concept where the device clock is divided down to a unit time. For PICmicro devices, this unit time is 4 times the device oscillator (4TOSC), also known as TCY.

Machine Code

Either object or executable code.

Macro

A collection of assembler instructions that are included in the assembly code when the macro name is encountered in the source code. Macros must be defined before they are used; forward references to macros are not allowed.

Master Synchronous Serial Port

The MSSP has two operational functions. The first is a ""Serial Peripheral Interface (SPI)"" and the second is the Inter-Integrated Circuit (""I2C""). The I2C function supports both master and slave functions in hardware.

MCU

Microcontroller Unit. An abbreviation for microcontroller. Also mC.

Memory Models

Versions of libraries and/or precompiled object files based on a device's memory (RAM/ROM) size and structure.

Microcontroller

A highly integrated chip that contains all the components comprising a controller. Typically this includes a CPU, RAM, some form of ROM, I/O ports, and timers. Unlike a general-purpose computer, which also includes all of these components, a microcontroller is designed for a very specific task - to control a particular system. As a result, the parts can be simplified and reduced, which cuts down on production costs.

MIPS

The unit commonly used to give the rate at which a processor executes instructions.

Mnemonics

Instructions that are translated directly into machine code. Mnemonics are used to perform arithmetic and logical operations on data residing in program or data memory of a microcontroller. They can also move data in and out of registers and memory as well as change the flow of program execution. Also referred to as Opcodes.

MPASM

Microchip Technology's relocatable macro assembler. MPASM is a DOS or Windows-based PC application that provides a platform for developing assembly language code for Microchip's PICmicro microcontroller families. Generically, MPASM will refer to the entire development platform including the macro assembler and utility functions.

MPLAB-CXX

Refers to MPLAB-C17 and MPLAB-C18 C compilers.

MPLAB-ICD

Microchip's in-circuit debugger for PIC16F87X devices. MPLAB-ICD works with MPLAB IDE. The MPLAB-ICD system consists of a module, header, demo board (optional), cables, and MPLAB Software.

MPLAB-ICE

Microchip's in-circuit emulator that works with MPLAB IDE.

MPLAB IDE

The name of the main executable program that supports the IDE with an Editor, Project Manager, and Emulator/Simulator Debugger. The MPLAB Software resides on the PC host. The executable file name is MPLAB.EXE. MPLAB.EXE calls many other files.

MPLAB-SIM

Microchip's simulator that works with MPLAB IDE.

MPLIB

MPLIB is a librarian for use with COFF object modules (filename.o) created using either MPASM v2.0, MPASMWIN v2.0, or MPLAB-C v2.0 or later. MPLIB will combine multiple object files into one library file. Then MPLIB can be used to manipulate the object files within the created library.

MPLINK

MPLINK is a linker for the Microchip relocatable assembler, MPASM, and the Microchip C compilers, MPLAB-C17 or MPLAB-C18. MPLINK also may be used with the Microchip librarian, MPLIB. MPLINK is designed to be used with MPLAB IDE, though it does not have to be. MPLINK will combine object files and libraries to create a single executable file.

MPSIM

The DOS version of Microchip's simulator. MPLAB-SIM is the newest simulator from Microchip.

MSb

Most Significant Bit.

MSB

Most Significant Byte.

MSSP

See ""Master Synchronous Serial Port.""

Non-Return to Zero (NRZ)

Two-level encoding used to transmit data over a communications medium. A bit value of '1' indicates a high voltage signal. A bit value of '0' indicates a low voltage signal. The data line defaults to a high level.

NRZ

See description under ""Non-Return to Zero (NRZ).""

Object Code

The intermediate code that is produced from the source code after it is processed by an assembler or compiler. Relocatable code is code produced by MPASM or MPLAB-C17/C18 that can be run through MPLINK to create executable code. Object code is contained in an object file.

Opcode

The portion of the 16-bit instruction word that specifies the operation that needs to occur. The opcode is of variable length depending on the instruction that needs to be executed. The opcode varies from 4-bits to 8-bits. The remainder of the instruction word contains program or data memory information.

Oscillator Start-up Timer (OST)

This timer counts 1024 crystal/resonator oscillator clock cycles before releasing the internal RESET signal.

OST

See description under ""Oscillator Start-up Timer (OST)"".

OTP

One-Time-Programmable

Pages

Method of addressing the Program Memory. Mid-range devices have 11-bit addressing for CALL and GOTO instructions, which gives these instructions a 2-Kword reach. To allow more program memory to be present on a device, program memory is partitioned into contiguous pages, where each page is 2-Kwords. To select the desired page, the page selection bits (PCLATCH<5:4>) need to be appropriately configured. Since there are presently 2 page selection bits, 4 pages can be implemented. The enhanced devices do not have paging. PIC16CXXX code migrates to the PIC18CXXX without modification (with respect to paging). Optimization may be implemented.

Parallel Slave Port (PSP)

A parallel communication port which is used to interface to a microprocessor's 8-bit data bus.

PC

Personal Computer or Program Counter.

PC Host

Any IBM® or compatible Personal Computer running Windows® 3.1x or Windows 95/98, Windows NT, or Windows 2000. MPLAB IDE runs on 486 or higher machines.

PICmicro® MCUs

PICmicro microcontrollers (MCUs) refers to all Microchip microcontroller families.

PICMASTER® Emulator

The hardware unit that provides tools for emulating and debugging firmware applications. This unit contains emulation memory, break point logic, counters, timers, and a trace analyzer among some of its tools. MPLAB-ICE is the newest emulator from Microchip.

PICSTART® Plus Device Programmer

A device programmer from Microchip. Programs 8-, 14-, 28-, and 40-pin PICmicro microcontrollers. Must be used with MPLAB Software.

POP

A term used to refer to the action of restoring information from a stack (software and/or hardware). See ""Serial Peripheral Interface (SPI).""

Postscaler

A circuit that slows the rate of the interrupt generation (or WDT Reset) from a counter/timer by dividing it down.

Power-on Reset (POR)

Circuitry which determines if the device power supply voltage rose from a powered down level (0V). If the device power supply voltage is rising from ground, a device RESET occurs and the PWRT is started.

Power-up Timer (PWRT)

A timer which holds the internal RESET signal low for a timed delay to allow the device voltage to reach the valid operating voltage range. Once the timer times out, the OST circuitry is enabled (for all crystal/resonator device oscillator modes).

Prescaler

A circuit that slows the rate of a clocking source to a counter/timer.

Program Bus

The bus used to transfer instruction words from the program memory to the CPU.

Program Counter

A register which specifies the address in program memory that contains the next instruction to execute.

Program Memory

The memory area in a PICmicro microcontroller where instructions are stored. Memory in the emulator or simulator containing the downloaded target application firmware.

Programmer

A device used to program electrically programmable semiconductor devices such as microcontrollers.

Project

A set of source files and instructions to build the object and executable code for an application.

PRO MATE® II Device Programmer

A device programmer from Microchip. Programs all PICmicro microcontrollers and most memory and KEELOQ® devices. Can be used with MPLAB IDE or stand-alone.

Prototype System

A term referring to a user's target application, or target board.

PWM Signals

See description under ""Pulse Width Modulation (PWM).""

PSP

See description under ""Parallel Slave Port (PSP).""

Pulse Width Modulation (PWM)

A serial signal in which the information is contained in the width of a (high) pulse of a constant frequency signal. A PWM output, from the CCP module, of the same duty cycle requires no software overhead. Pulse Width Modulation Signals. Certain PICmicro devices have a PWM peripheral.

PUSH

A term used to refer to the action of saving information onto a stack (software and/or hardware). See ""Serial Peripheral Interface (SPI).""

PWM

See description under ""Pulse Width Modulation (PWM).""

Q-cycles

This is the same as a device oscillator cycle. There are 4 Q-cycles for each instruction cycle.

RAM

Random Access Memory (Data Memory).

Raw Data

The binary representation of code or data associated with a section.

RC

Resistor-Capacitor. The default configuration for the device oscillator. This allows a ""Real-Cheap"" implementation for the device clock source. This clock source does not supply an accurate time-base.

Read-Modify-Write

This is where a register is read, then modified, and then written back to the original register. This may be done in one instruction cycle or multiple instruction cycles.

Register File

This is the Data Memory. Contains the SFRs and GPRs.

Real-Time

When released from the halt state in the emulator or MPLAB-ICD mode, the processor runs in real-time mode and behaves exactly as the normal chip would behave. In real-time mode, the real-time trace buffer of MPLAB-ICE is enabled and constantly captures all selected cycles, and all break logic is enabled. In the emulator or MPLAB-ICD, the processor executes in real-time until a valid break point causes a halt, or until the user halts the emulator. In the simulator real-time simply means execution of the microcontroller instructions as fast as they can be simulated by the host CPU.

ROM

Read Only Memory. Memory that is fixed and cannot be modified.

Sampling Time

Sampling time is the complete time to get an A/D result. It includes the acquisition time and the conversion time.

Serial Peripheral Interface (SPI)

This is one of the modes of the ""SSP"" and ""MSSP"" modules. This is typically a 3-wire interface, with a data out line, a data in line, and a clock line. Since the clock is present, this is a synchronous interface.

Section

An portion of code or data which has a name, size, and address.

SFR

Special Function Register. These registers contain the control bits and status information for the device.

Shared Section

A section which resides in a shared (non-banked) region of data RAM.

Simulator

A software program that models the operation of the PICmicro microprocessor.

Single Cycle Instruction

An instruction that executes in a ""single"" machine cycle (TCY).

SLEEP

This is a low power mode of the device, where the device's oscillator circuitry is disabled. This reduces the current the device consumes. Certain peripherals may be placed into modes where they continue to operate.

Source Code - Assembly

Source code consists of PICmicro instructions and MPASM directives and macros that will be translated into machine code by an assembler.

Source Code - C

A program written in the high level language called ""C"" which will be converted into PICmicro machine code by a compiler. Machine code is suitable for use by a PICmicro MCU or Microchip development system product like MPLAB IDE.

Source File - Assembly

The ASCII text file of PICmicro instructions and MPASM directives and macros (source code) that will be translated into machine code by an assembler. It is an ASCII file that can be created using any ASCII text editor.

Source File - C

The ASCII text file containing C source code that will be translated into machine code by a compiler. It is an ASCII file that can be created using any ASCII text editor.

Special Function Registers (SFR)

These registers contain the control bits and status information for the device.

SPI

See description under ""Serial Peripheral Interface (SPI).""

SSP

Synchronous Serial Port. The SSP has two operational functions. The first is a ""Serial Peripheral Interface (SPI™)""and the second is the Inter-Integrated Circuit (""I2C™""). The I2C function supports the slave function in hardware and has additional status information to support a software implemented master.

Stack - Hardware

An area in PICmicro MCU memory where function arguments, return values, local variables, and return addresses are stored; i.e., a ""Push-Down"" list of calling routines. Each time a PICmicro MCU executes a CALL or responds to an interrupt, the software pushes the return address to the stack. A return command pops the address from the stack and puts it in the program counter. The PIC18CXXX family also has a hardware stack to store register values for ""fast"" interrupts.

Stack - Software

The compiler uses a software stack for storing local variables and for passing arguments to and returning values from functions.

Static RAM or SRAM

Static Random Access Memory. Program memory you can Read/Write on the target board that does not need refreshing frequently.

TAD

In the A/D Converter, the time for a single bit of the analog voltage to be converted to a digital value.

Target

Refers to user hardware.

Target Application

Firmware residing on the target board.

Target Board

The circuitry and programmable device that makes up the target application.

Target Processor

The microcontroller device on the target application board that is being emulated.

TCY

The time for an instruction to complete. This time is equal to Fosc/4 and is divided into four Q-cycles.

Tosc

The time for the single period of the device oscillator.

USART

Universal Synchronous Asynchronous Receiver Transmitter. A module that can operate as a full duplex asynchronous communications port or as a half duplex synchronous communications port. When operating in the asynchronous mode, the USART can be interfaced to the PC serial port.

Upload

The Upload function transfers data from a tool, such as an emulator or programmer, to the host PC or from the target board to the emulator.

Voltage Reference (VREF)

A voltage level that can be used as a reference point for A/D conversions (AVDD and AVSS) or the trip point for comparators.

Von Neumann Acrchitecture

In this architecture the Program memory and Data Memory are contained in the same area. This means that accesses to the program memory and data memory must occur sequentially, which affects the performance of the device.

WatchDog Timer (WDT)

A timer on a PICmicro microcontroller that resets the processor after a selectable length of time. The WDT is enabled or disabled and set up using configuration bits.