@ware eduproto iii user guide2

@Ware EduProto III- 4553 Embedded System Design and Programming Guide using Microchip™ PIC18F4553/4550 and @Ware Executive Subjacent System A student guide that gives instructions on how to implement an educative embedded system platform based on Microchip™ PIC18F4553/4550, a high performance 12MIPS 8-bit microcontroller with USB 2.0 Full Speed support. Also includes @Ware ESS SDK documentation for application developers on @Ware Executive Subjacent System. In this guide students will discover an easy way to learn the electronics, informatics, digital signal processing and digital control involved in the design, development and testing of embedded system applications.

2010

M. Sc. Pedro Arturo Cornejo Torres @Ware Systems

01/04/2010

@Ware Systems M.Sc. Pedro Arturo Cornejo Torres

2

@Ware EduProto III- 4553 Embedded System Design and Programming Guide using

Microchip™ PIC18F4553/4550 and @Ware Executive

Subjacent System

By M. Sc. Pedro Arturo Cornejo Torres

Abstract

A student guide that gives instructions on how to implement an educative embedded system

platform based on Microchip™ PIC18F4553/4550, a high performance 12MIPS 8-bit

microcontroller with USB 2.0 Full Speed support. Also includes @Ware ESS SDK documentation

for application developers on @Ware Executive Subjacent System. In this guide students will

discover an easy way to learn the electronics, informatics, digital signal processing and digital

control involved in the design, development and testing of embedded system applications.

QUEDAN PROHIBIDOS EL USO Y LA REPRODUCCIÓN TOTAL O PARCIAL DE ESTE DOCUMENTO

POR CUALQUIER MEDIO SIN PERMISO POR ESCRITO O CONCENTIMIENTO DEL AUTOR

Copyright © M. en C. Pedro Arturo Cornejo Torres MMX

[email protected]

Guadalajara, Jalisco, México

Microsoft, Microchip y demás marcas y productos mencionados en este documento, son

nombres y marcas registradas por sus respectivas compañías.

mailto:[email protected]


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Table of Contents

1 Introduction .......................................................................................................................... 5

2 Assembling the @Ware EduProto III-4553 microcontroller educative platform .................. 6

2.1 @Ware EduProto III-4553 Schematic Diagram ............................................................. 7

2.2 Part list .......................................................................................................................... 8

3 @Ware Executive Subjacent System v2.5 ............................................................................. 9

3.1 @Ware ESS v2.5 Features ............................................................................................. 9

3.2 @Ware ESS Memory Organization in a PIC18F4553 ................................................... 10

4 @Ware ESS Program Memory and User Application .......................................................... 10

4.1 User Application Entry Point ....................................................................................... 11

4.2 Interrupt Vectors and Interrupt Handlers ................................................................... 11

4.3 System Calls ................................................................................................................. 12

4.4 API Access .................................................................................................................... 13

4.5 Configuration settings for PIC18F4553 ....................................................................... 13

5 @Ware ESS Operation ........................................................................................................ 15

5.1 The ESSCONTROL flags ................................................................................................ 17

6 USART .................................................................................................................................. 18

7 Preparing a User Application Workspace in MPLAB ........................................................... 19

7.1 Workspace and project creation ................................................................................. 19

7.1.1 Step 1: Starting MPLAB IDE ................................................................................. 19

7.1.2 Step 2: Creating a PIC18F4553 workspace and developer tools association ...... 19

7.1.3 Step 3: PIC Model Selection. ............................................................................... 20

7.1.4 Step 4: Tool suite selection ................................................................................. 20

7.1.5 Step 5: Workspace and project name. ................................................................ 21

7.1.6 Step 6: Workspace naming and location ............................................................. 21

7.1.7 Step 7: Workspace and Project information verification .................................... 22

7.1.8 Step 8: Adding existing files to the project ......................................................... 22

7.1.9 Step 9: Executing project creation and settings .................................................. 23

7.2 Adding required files into the project to develop applications based on @Ware ESS

v2.5 24

7.3 Configuring Code and Data Models and Code Generation using Extended Instruction

Set 30


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8 Simulating and debugging applications in MPLAB .............................................................. 33

8.1 Enabling MPLAB SIM ................................................................................................... 33

8.2 Microcontroller Configuration Bits used in simulation ............................................... 33

8.3 Debugger Settings ....................................................................................................... 35

8.4 Timing while application is simulated ......................................................................... 36


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1 Introduction In the last years, microcontrollers have been used successfully in many applications such as

communications, human interface devices, entertainment, commodities, mobile devices,

remote controls, robots, automotive industry, heavy industry, medical devices, and more

others. The reasons that justify the need of learning and understanding the great world of

microcontrollers are more than clear. Embedded systems that are based on microcontrollers

are everywhere, even in the space.

Currently, powerful microcontrollers are available from multiple providers as Freescale,

Microchip, Atmel, Intel and others. Firmware developers for these microcontrollers have

adopted the C language to accelerate the development of complex embedded systems. These

projects must accomplish both hardware and software requirements to be reliable, safe,

efficient and precise. Embedded system design is not only firmware programming work, it also

involves knowledge and practical skills in electronics and digital control, because most

embedded system applications implies some kind of digital signal processing and control. You

must be proficient in computer programming to build, in most cases in embedded design, time

critical firmware. The proper use of computing power provided by the CPU cores, the correct

and adequate use of the peripherals inside modern microcontroller and good circuitry design,

will lead to cost effective and efficient solutions for industrial production, office and home

applications.

With this document, users can learn how to implement a powerful educative embedded

system platform using Microchip™ PIC18F4553 microcontroller. This educative platform is

called @Ware EduProto III-4553. With this microcontroller platform users can develop and test

a considerable number of embedded applications. With 12MIPS of computing power and USB

connectivity that PIC18F4553 microcontroller provides, users will find a modern and

convenient way to learn embedded systems design and programming.


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2 Assembling the @Ware EduProto III-4553 microcontroller

educative platform The purpose of this section is to give you guidance on what do you need to build your own

hardware based on Microchip PIC18F4553 microcontroller. The special selection of

components and their interconnection will make your new hardware compatible with @Ware

Executive Subjacent System Firmware, or simply @Ware ESS. The hardware configuration has

been called @Ware EduProto III-4553 and it is capable of connectivity with a personal

computer by the use of microcontroller’s on-chip USB and @Ware ESS firmware.

Detailed information about Microchip PIC18F4553 can be found at www.microchip.com.

Download the datasheet and use it as primary reference while you are assembling or

programming the device.

The @Ware EduProto III-4553 platform has the following features:

Microchip PIC18F4553 as main microcontroller chip. Its RISC CPU core is based on

Harvard architecture running at 48MHz and executes instructions as fast as 12 MIPS. It

includes 32KB of Flash EEPROM accessible as program space, 2KB of static RAM

accessible as data space and 256 bytes of EEPROM. The PIC18F4553 contains a USB 2.0

Full Speed transceiver, 5 I/O ports, 20 interrupt sources, 4 timers, 2 Capture-Compare-

PWM Modules, Enhanced USART RS-232, LIN capable, I2C or SPI Communication

Module, A 12-bit ADC with 13 multiplexed channels, 3 oscillators for clock source,

power managed operation modes and more.

USB Type B Connector Receptacle. Supports mechanical and reliable USB connection

with @Ware EduProto III-4550 and a host personal computer. You can use an USB A/B

cable to connect a host personal computer and @Ware EduProto III-4553. This allows

an embedded application to exchange information with a PC or to be used for

developing purposes when @Ware ESS is executing. This is a cost-effective method for

loading firmware from PC. To load, erase or execute programs on the PIC18F4553,

please use @Ware Embedded SDK Tools.

Autorun Switch. Allows automatic application program execution when powered up or

user reset. The application program will start after @Ware ESS initializes chip and USB

possible connection with a host is configured. A USB configured connection is not

required for application program start.

Reset Button. A button that is always required in development and test process. If

something is wrong with the firmware execution or PIC18F4553 does not respond to

user commands or simply a crash occurs, you will have to press it.

Dual Power Source with on board 5V-1A regulator. An automatic switch circuit allows

@Ware EduProto III-4553 to be powered directly from VUSB or an external 12V-35V

power source. If the external power source is available then it will be used as primary

source and no current will be drained from VUSB. If external power source is not

present, VUSB will be used, draining current from the host device. If VUSB is used then

the embedded application must not exceed the 500mA limit defined by the USB 2.0

specification. The maximum current provided by the switch transistor is 500mA.

http://www.microchip.com/


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2.1 @Ware EduProto III-4553 Schematic Diagram This is the schematic diagram of the @Ware EduProto III-4553. You can use a prototyping

breadboard or design your own printed circuit board. Take into account distances between

certain circuit elements to avoid noise induction and erratic operation.


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2.2 Part list @Ware EduProto III-4553 is very simple and requires a few components to work. Please,

download important datasheets related with listed semiconductors.

Table 1 @Ware EduProto III-4553 part list

Part Label Part Identifier or value

R1,R2 1KΩ ¼ W

R3,R4 100KΩ ¼ W

R5,R9 10KΩ ¼ W

R6,R7 330Ω ¼ W

R8 4.7KΩ ¼ W

R10 47KΩ ¼ W

C1,C2 22pF Ceramic Capacitor

C3 220nF Polyester Capacitor

C4 10uF Electrolytic Capacitor

C5 1uF Electrolytic Capacitor

X1 4MHz Crystal

D1,D4 1N4001 1A Rectifier Diode

D2,D3 LED

Q1 PN2907 - 500mA or 2N3906 -100mA. General Purpose Amplifier PNP Transistor

SW1 Push button

SW2 Mini-switch SPST

J1 USB Type B Receptacle

U1 IC PIC18F4553-I/P Microcontroller programmed with @Ware Executive Subjacent System v2.5 or higher.

U2 IC 7805 Positive 5V regulator


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3 @Ware Executive Subjacent System v2.5 The @Ware EduProto III-4553 platform uses a PIC18F4553 microcontroller programmed with

@Ware Executive Subjacent System v2.5 firmware. This is required in order to be ready to

load, erase and execute user programs into microcontroller directly from PC. @Ware ESS

avoids the need of an expensive universal device programmer. Students only need access to a

device programmer when they load the firmware. This also reduces cost in laboratory

equipment using at least one device programmer for scheduled massive firmware

programming. Some @Ware ESS portions are based on a customized version from Microchip

USB Application Framework. The Microchip USB Application Framework can be downloaded

from www.microchip.com.

3.1 @Ware ESS v2.5 Features The @Ware ESS firmware has the following features:

@Ware ESS sets a versatile chip configuration that enables the PIC18F4553

microcontroller functionality when powered up. This configuration includes activation

of the extended instruction set to be used by optimized C compilations. @Ware ESS

also activates a 48MHz clock generator to execute up to 12MIPS. More detailed

information about chip configuration established by @Ware ESS, please see section

4.5 Configuration settings for PIC18F4553 in page 13.

@Ware ESS enables users to upload, execute and erase user application firmware

from the PC. This is done using @Ware ESS SDK tools. For more detailed information

about these tasks, please see…

When @Ware EduProto III-4553 is connected with an USB host, @Ware ESS emulates

a device connected to PC via a COM port. Users can develop applications for the PC

that directly communicate with @Ware EduProto III-4553.

@Ware ESS implements a state machine for a logical communication protocol using

data packets with simple datagram structure. More detailed information about how

to create PC applications that have communication with @Ware ESS and @Ware

EduProto III-4553, please see ...

@Ware ESS shares its communication protocol with both the USB emulated COM

port and the on chip USART. When @Ware EduProto III-4553 is powered up, the

USART is configured at 250,000bps allowing asynchronous mode communication with

other nearby devices. The communication is done using ping-pong like byte

transactions and time out count to avoid stall.

@Ware ESS communication protocol and state machine can be extended to use I2C or

other underlying hardware protocol.

@Ware ESS does not handle any interrupt vector. @Ware ESS redirects interrupt

vectors to user application. This is to avoid high latency when handling interruptions

and improve application responsiveness when an interrupt event occurs. Also, allows

users to manage interrupts in many ways improving design flexibility. See Section 4.2

Interrupt Vectors and Interrupt Handlers in page 11 for details.

@Ware ESS supports power managed modes. Using @Ware ESS facilities, a simple

system call can be done to change clock speed. @Ware ESS implements three power

managed modes: Full Power Mode (48MHz), Low Power Mode (8MHz-31250Hz) and



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Sleep Mode. The last mode is invoked by the USB host device or a proper execution of

a sleep instruction. More information about power managed modes, please see…

3.2 @Ware ESS Memory Organization in a PIC18F4553 Once firmware was programmed on a PIC18F4553 microcontroller, @Ware ESS requires the

first 8192 bytes in the program memory and there are 24KB of free program memory for user

application code. A detailed @Ware ESS memory organization is given in Figure 1. The

application may use @Ware ESS facilities to initiate, use and terminate an USB connection with

a host, reducing user application code size. Also, @Ware ESS reserves 512 bytes of RAM only if

the user application intends to use @Ware ESS facilities. The first 8192 bytes of program space

are not available for reading or writing while user’s application is in execution. Write

protection and copy protection are enabled to avoid illegal copies and accidental overwrite on

@Ware ESS code. Execution permission of @Ware ESS code is allowed through system calls.

Only a device programmer can erase @Ware ESS.

4 @Ware ESS Program Memory and User Application @Ware ESS is written in the first 8192 bytes of program memory. This memory cannot be used

to store user application code, because @Ware ESS configuration has write protected its code.

Since user application code cannot be written in that memory block, the user application code

Free

1KB

Program Memory

0x000000

0x007FFF

0x001FFF

@Ware ESS

Program Code

8KB

Free

24KB

0x0000-0x03FF

0x0400-0x05FF

0x0600-0x06FF

@Ware ESS Data 512Bytes

Free 256 Bytes

Software Stack 256 Bytes

0x0700-0x07FF

0x002000

Data Memory

SFR Bank

Not implemented

0x0F60-0x0FFF

Figure 1 @Ware ESS memory organization


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must be stored starting at program memory address 0x002000. @Ware ESS exposes an

application interface to implement interrupt handlers and perform system calls.

4.1 User Application Entry Point The special reset vector at address 0x000000 is always handled by @Ware ESS and it is not

redirected. When @Ware ESS has initialized the PIC18F4553 and run application command is

in progress, then @Ware ESS uses a call instruction to address 0x002000. The address

0x002000 is always the entry point for user applications. When user application ends and

executes the outer return instruction, @Ware ESS will take execution control. It is not

required by user application to return execution control to @Ware ESS when finished. This

could be true because user application may stay in a loop or waiting for interrupts to occur.

4.2 Interrupt Vectors and Interrupt Handlers An interrupt vector is simply an address of a pointer to or an overlay to a function that handles

or services an interrupt event. An overlay is generally a simple goto instruction that redirects

execution control to another part of the program. Both overlays and interrupt handlers are

required when using a PIC18F4553.

The PIC18F4553 exposes only two interrupt vectors: a High Priority Interrupt vector and a Low

Priority Interrupt vector. The High Priority Interrupt vector is located at program memory

address 0x000008 and low priority interrupt vector is located at program memory address

0x000018. See Figure 3 to know how interrupt redirection is done.

@Ware ESS implementation redirects the High Priority Interrupt vector from address

0x000008 to address 0x002008. The program memory address 0x002008 becomes the new

vector to a High Priority Interrupt handler.

@Ware ESS

User Application

0x002000

If Autorun is activated or Run Application command is in progress, the execution is transferred to address 0x002000. In any case the PIC18F4553 has been initialized and Full Power is activated.

0x000000

User Application

Entry Point

Program Memory

Figure 2 User Application Entry Point


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The Low Interrupt Vector is redirected from program memory address 0x000018 to address

0x002018. The address 0x002018 becomes the new vector to a Low Interrupt Priority Interrupt

handler.

The redirected vectors 0x002008 and 0x002018 are available to be defined by user application.

4.3 System Calls User applications can invoke functionality provided by @Ware ESS. This can be done through a

system call. A system call is performed using ESS_SystemCall macro. System calls are

provided to perform common tasks that @Ware ESS already solves, like USB communication

tasks, USART tasks, status Tx/Rx LEDs tasks, power management and more.

@Ware ESS

User Application

Application must implement overlays

and handlers if activates and uses

interrupts. The application saves and

restores application context in the

interrupt handler. Microchip C18

compiler automatically generate code

that saves and restores application

context.

0x000008

Redirected interrupt vectors

Program Memory

0x000018

0x002008

0x002018

Low Priority Interrupt Vector

goto 0x002008

goto 0x002018

goto MyHPIHandler

goto MyLPIHandler

Figure 3 Interrupt vectors redirection

High Priority Interrupt Vector


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4.4 API Access User application can use an API set to use even more granular functionality from @Ware ESS.

An API set is a table of pointers to data or pointers to functions. These pointers can be used to

perform direct calls to specific functions or for accessing data memory locations that @Ware

ESS uses. Currently there are two API sets: the USB_API and USART_API. Lower level

functionality like USB data transfers functions are only available through these API sets. See

SDK for more details. To query for a pointer to an API set, the application must use the

ESS_GetAPI macro and provide one of these values: API_INDEX_USB or

API_INDEX_USART.

4.5 Configuration settings for PIC18F4553 When @Ware ESS is programmed into a PIC18F4553 an initial hardware configuration is

established in order to operate. This initial configuration is stored in flash program memory

when device is programmed. The Table 2 is an important reference when using and

configuring microcontroller’s peripherals. The configuration is applied by hardware each time

the PIC18F4553 microcontroller is powered up, defining a hardware profile that cannot be

changed during software execution. Write protection is enabled on those bits to ensure

coherence with external components, and be able to execute @Ware ESS and user application

code. Users can erase configuration using a device programmer, doing so, will also erase

@Ware ESS.

@Ware ESS

User Application User Application can use @Ware

ESS functionality performing a

sytem call when it needs.

System Call Vector

Program Memory

0x000180 System Call Handler

call 0x000180

Note: A system call must be supplied with a

command ID and its parameter using software stack.

A system call eventually returns with a result placed

in W register.


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Table 2 PIC18F4553 Configuration bits values established by @Ware ESS firmware

Configuration bits Description of current configuration

PLLDIV = 1 No prescale (4 MHz oscillator input drives PLL directly)

CPUDIV = OSC1_PLL2 CPU Clock = 48MHz

USBDIV = 2 USB clock source comes from the 96 MHz PLL divided by 2

FOSC = XTPLL_XT XT oscillator, PLL enabled, XT used by USB

FCMEN = ON Fail-Safe Clock Monitor enabled

IESO = ON Oscillator Switchover mode enabled

PWRT = ON PWRT enabled

BOR = SOFT Brown-out Reset enabled and controlled by software (SBOREN is enabled) 1

BORV = 3 Minimum setting (2V)

VREGEN = ON USB voltage regulator enabled

WDT = OFF Watchdog HW Disabled - SW Controlled 2

WDTPS = 256 4ms*256 WDT Period

MCLRE = ON MCLR pin enabled; RE3 input pin disabled

LPT1OSC = OFF Timer1 oscillator configured for higher power operation

PBADEN = OFF PORTB<4:0> pins are configured as digital I/O on Reset

CCP2MX = OFF CCP2 input/output is multiplexed with RB3

STVREN = ON Stack full/underflow will cause Reset

LVP = OFF Single-Supply ICSP disabled

ICPRT = OFF Dedicated In-Circuit Debug/Programming ICPORT disabled

XINST = ON Instruction set extension and Indexed Addressing mode enabled

1 Brown-out Reset is disabled by firmware when @Ware ESS starts, users can enable BOR.

2 Watch Dog Timer is disabled by default when @Ware ESS starts, users can enable WDT.


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5 @Ware ESS Operation The normal operation of @Ware ESS on @Ware EduProto III-4550 can be explained with the

following pseudo code. During @Ware ESS operation, no interruptions are handled because it

is designed for low resource consumption. In fact, @Ware ESS is implemented in a pooling

basis.

void ESSMain(void)

RCONbits.SBOREN=0;

ESSCONTROL=0;

ESSCONTROLbits.g_bRunProgram:=PORTAbits.RA5; //Autorun?

InitializeStatusLEDs();

InitializeUSART();

InitializeADC();

while(1) //Do forever

ESS_USBDeviceTasks();

ESS_USARTTasks();

if( ESSCONTROLbits.g_bRunProgram ||

ESSCONTROLbits.g_bLoopProgram )

ESSCONTROLbits.g_bRunProgram=TRUE;

If(UserApplicationIsLoaded)

ExecuteUserApplication();

DisableAllInterrupts();

ReInitializeUSB();

ReInitializeUSART();

ReInitializeADC();

else if(USBDeviceIsNotConnected)

SleepAndWaitForUSBConnection();

// end while

//end while

When pressing Reset button or powering up the @Ware EduProto III-4553, the following

occurs:

If @Ware EduProto III-4553 is powered only by the USB host, @Ware ESS opens a

connection with the host even if the Autorun switch was closed (enabled). User

application must disable the USB SIE (clear UCON<USBEN> bit), if USB communication

is not used. Also, if AutoRun switch was opened, @Ware ESS will take execution

control, otherwise user application is executed.

If @Ware EduProto III-4553 is powered by external power source and AutoRun switch

was closed, @Ware ESS will disable USB SIE before user application starts. Also, if user


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application is not loaded, @Ware ESS will enter in Sleep Mode waiting for USB

connection. When USB connection occurs, @Ware ESS will open a connection and

takes execution control.


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5.1 The ESSCONTROL flags ESSCONTROL is a private variable used by @Ware ESS to store control flags. These flags reflect

the state of some features. There are six flags defined that are accessible to user application.

Here is a description of these flags. The ESSCONTROL variable is accessible for reading or

writing through a system call. See system call commands for more information.

Table 3 Description of the @Ware ESS control flags

Bit # Bit Name Description

0 (LSB) g_bRunProgram This flag is set when one of the following conditions is meet: 1) When Autorun switch is closed when a reset event or power up

event occurs. 2) When a Run Program command is received from a USB host.

User application must not clear this flag. This flag is always set when user application is in execution.

1 g_bLowPower This flags indicates if low power mode is activated. When @Ware ESS starts this flag is clear and Full Power Mode. In Full Power Mode, CPU and peripherals are clocked at 48MHz. User application can set this bit to enter Low Power Mode. In Low Power Mode, CPU and peripherals are clocked at 8MHz using INTOSC. User application can modify OSCCON<IRCF2:IRCF0> bits to select different frequencies. Warning: Using frequencies below 2MHz may not be fast enough to hold or initiate a stable USB connection due to slow firmware execution. Note: Changing CPU and peripherals frequency does not affect USB SIE clock source. USB SIE uses only 48MHz clock source always. This bit is clear by default.

2 g_bStatusLEDEnable User application sets this flag to activate Tx/Rx LED notifications. If user application clears this flag high impedance is seen in RE0 and RE1. This can be used for energy save. This flag is set by default.

3 g_bUSBEnable If this flag is set USB SIE hardware and firmware driver are enabled to initiate and hold USB connectivity with a host. If this bit is clear, no USB connections are allowed and USB SIE is disabled. In this case USB host will declare a disconnection even if PIC18F4553 microcontroller remains plugged. User application can clear and then set this flag to reinitialize USB driver in case of communication problems. This flag is set by default.

4 g_bLoopProgram The user application sets this flag if it is required that @Ware ESS executes user application again each time it returns. After each iteration @Ware ESS clears GIE/GIEH, GIEL/PEIE, IPEN, SWDTEN bits and then initializes ADC, USART and USB (if disabled). No RAM cleaning or other initializations are performed. This flag is clear by default.

5 g_bAllowSuspend If this flag is set by user application, PIC18F4553 microcontroller will be allowed to enter Sleep Mode when USB host sleeps. By default, the user application execution will not be suspended when the USB host sleeps. This flag is clear by default.

6 Reserved User application must not modify this flag.

7 (MSB) Reserved User application must not modify this flag.

The following sequence shows how to read and modify ESSCONTROL flags.

1. User application must first read the current ESSCONTROL state using

ESS_QueryESSCONTROL macro.


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2. Using logic masks user application can set or clear specific flags.

3. Finally, use ESS_WriteESSCONTROL macro to update @Ware ESS with the new

configuration. Users can also use uESSCONTROL union type provided with @Ware

ESS SDK.

This is a C code example.

#include “interface.h” //@Ware ESS Interface Header included

...

unsigned char ESSCONTROL;

...

//Read ESSCONTROL status first using a system call

ESSCONTROL=ESS_QueryESSCONTROL();

//Modify flags, in this case, turn off USB Notification LEDs

ESSCONTROL = ESSCONTROL & 0xFE;

//Update ESSCONTROL register using a system call

ESS_WriteESSCONTROL(ESSCONTROL);

6 USART

48000000 25 115384.615 115200 416 1040

8000000 25 19230.7692 19200 416 1040

4000000 25 9615.38462 9600 416 1040

2000000 25 4807.69231 4800 416 1040

1000000 25 2403.84615 2400 416 1040

500000 25 1201.92308 1200 416 1040

250000 25 600.961538 600 416 1040

125000 25 300.480769 300 416 1040

31250 25 75.1201923 75 416 1040

See… @Ware Embeded Software Developer Kit. Every system call requires two parameters: a

function ID (1 byte size) and its function parameter (3 bytes size). These parameters must be

pushed into software stack, then perform a call instruction to address 0x000180. When

returning from a system call, the application needs to restore the stack. The address 0x000180

is the entry point for a system call runtime in @Ware ESS program space.


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7 Preparing a User Application Workspace in MPLAB To develop and cross compile a solution based on @Ware ESS, you can use Microchip MPLAB

IDE and Microchip C18 compiler. These software packages can be downloaded from

www.microchip.com.

7.1 Workspace and project creation The following examples are supposing that the developer user has already installed MPLAB IDE

and the academic version of Microchip C18.

7.1.1 Step 1: Starting MPLAB IDE

Start MPLAB IDE from the corresponding Microchip’s program group. When the IDE is ready,

an untitled project is opened. In the next step, a new workspace will be created and

corresponding tools will be activated.

7.1.2 Step 2: Creating a PIC18F4553 workspace and developer tools association

From the “Project” menu, choose “Project Wizard” command. The following figure shows the

“Project Wizard” presentation window. Press the “Next” button to continue.



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7.1.3 Step 3: PIC Model Selection.

From the device list, choose PIC18F4553. This informs to wizard to prepare tools related with

this PIC model. Press the “Next” button to continue.

7.1.4 Step 4: Tool suite selection

From the Active Tool Suite dropdown list, choose “Microchip C18 Toolsuite”. In the next step

the project name and its location will be defined. Press the “Next” button to continue.


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7.1.5 Step 5: Workspace and project name.

In the following dialog box, define a new project name. It is recommended the use of “Browse”

button to locate and create a known place for project files. Press the “Browse” button.

7.1.6 Step 6: Workspace naming and location

Locate a known place and create a folder named “ESSAPP01” in the “Save As” dialog, finally

define the Workspace file name as “ESSAPP01”. Press the “Save” button to close the “Save as”

dialog box.


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7.1.7 Step 7: Workspace and Project information verification

Now, the project name and its location have been defined. Press the “Next” button to

continue. Please check file pathname to be sure about actions performed.

7.1.8 Step 8: Adding existing files to the project

The project and workspace are almost ready. In the following figure, the wizard is asking for

already existing files. Simply press “Next”.


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7.1.9 Step 9: Executing project creation and settings

This is the final step of the workspace creation and configuration. A summary will be

presented. Please check for correct information. If something is not as expected, go back and

modify the information provided. Press “Finish” button to continue.


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7.2 Adding required files into the project to develop applications

based on @Ware ESS v2.5 In the later section, a project and its workspace have been created and configured.

Now, it is required to add new files. A basic set of files must be copied where project is

situated. The following files must be copied into project’s folder.

File name Brief description

startup.c @Ware Systems modified startup code written in C language. This code will initialize any global variable that any source file declares and initializes. Must be compiled and linked with the other project’s files. The code establishes the first sequence of instructions to be executed before main function executes. The startup code puts the first instruction at program address 0x002000. Do not exclude this file or the application will not be able to start from the main function. This file can be founded in the \startup folder of your @Ware ESS SDK package.

ESSAPP_18F4553.lkr The required linker script. This file defines the memory maps for code and data. The linker must execute this script as part of the project. This informs the linker where code and data must be correctly located. Three important items are defined: The Software Stack Segment, Code Segment and Data Segments. This file can be founded in the \lkr folder of your @Ware ESS SDK package.

command.h (Optional) If you intent to execute host commands into your @Ware EduProto III-4553, then this file must be added into your Visual Studio Solution and in your MPLAB workspace. It contains important structures and types related with command packing and communications between a PC and @Ware EduProto III-4553 using USB connection.

interface.h (Optional) If you intent to use @Ware ESS facilities in your application, this file must be included in your source code. This header file also includes “command.h” header file into your implementation


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automatically. It contains all the required structures, constants, macros and types required to perform invocations and callbacks using @Ware ESS v2.5 firmware.

The following figure shows the project’s folder with these new files as its contents.

Now that files have been copied into the project’s folder, it is required to add them as part of

the projects. Only copying those files into the project’s folder does not mean that them will be

compiled or executed. Project’s configuration must be aware of those files too in order to

process them. Right click on project’s name “ESSAPP01.mcp” in workspace view and choose

“Add files...” command from the emerging popup menu. See the figure below.


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Once clicked, a dialog box will appear asking for files to add. Use the “jump to” dropdown list

and choose “Project Directory”. Doing so will change the current directory view to the project

folder. Also be sure to check the options showed in the following figure. These options must be

checked: “Remember this settings” and “User: Files where created especially for this project,

use relative path”. This will allow exporting, copying or transferring your project elsewhere,

since it uses relative paths.

Now select the above mentioned files and add them into the project. You can use “Ctrl” key

while clicking on specific files. Please, be sure to set the file filter to “All files (*.*)” to perform

a single aggregation operation. You can use this method to add more files. It is recommended

that existing files must be copied first into project’s folder. When you are done, press the

“Open” button to add the specified files. See the following figure to confirm how this selection

is done.


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After aggregating files is done, the IDE looks like this.

Finally, create a C source file called “main.c”. This will be your primary source file. Right click

on the project’s name at workspace view and choose “Add new file...” command. This is shown

in the following figure.


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In the “Add new file to project” dialog box at the “Name” write “main.c” as the new file name.

Please, be sure to locate your project’s folder before pressing “Save” button.

Now, after creating the “main.c” file, a new edition window will be opened. See following

figure.


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Please do not write any code or compile it yet. It is needed to configure the code and data

models before to start. See next section to perform this final configuration.


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7.3 Configuring Code and Data Models and Code Generation using

Extended Instruction Set @Ware ESS firmware had configured the PIC18F4553 microcontroller to be able to use the

Extended Instruction Set. Therefore, the application must use Extended Instruction Set too.

Some options must be configured before any compiling or linking process may occur.

Again, right click on the project’s name at workspace view and choose “Build options...”

command. See the following figure that shows how to do this.

The following dialog box will appear after command selection. Click on the “Directories” tab

and add the specified entry in the figure. This will inform to linker where standard libraries

might be found. See following figure to see which entry must be added. The entry path may be

totally different if you did choose a different directory when Microchip C18 was installed.


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Now in the “MPLAB C18” tab, be sure the following configuration meets. This will activate an

adequate code, data and stack model.


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And the following too, to generate optimized code.

Now, it is time to enable extended instruction set. See the following figure. Please be sure to

mark “Extended mode” check box. This will enable the linker to generate code that uses the

Extended Instruction Set. If you do not activate this, the generated code will be unable to

execute in @Ware EduProto III-4553 platform.

At this point, press OK and you will be ready to develop. Get Fun!


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8 Simulating and debugging applications in MPLAB Before to upload the firmware into microcontroller, it is possible to simulate and debug the

application. This can be done using MPLAB SIM. Simulation is a very effective technique to

analyze the execution evolution and can be used for timing the application without using a real

microcontroller. This can save time and reduce developing costs.

8.1 Enabling MPLAB SIM To enable MPLAB SIM, just choose the “MPLAB SIM” debugger tool under “Debugger” menu.

This is shown in the figure below.

Once MLAB SIM is enabled you can set any number of breakpoints in the application’s source

code using the source editor. To set or clear a breakpoint, just double click on the source line

of interest.

8.2 Microcontroller Configuration Bits used in simulation It is required to define witch set of instructions will be simulated. PIC18F4550/4553

microcontroller has two instruction sets: Traditional Instruction Set and Extended Instruction

Set. @Ware ESS is implemented using Extended Instruction Set and applications must be

implemented using the same instruction set. This is also required when simulating the

application. To enable simulation of the Extended Instruction Set, open the “Configuration

Bits” window under “Configure” menu as shown in the figure below.


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When the “Configuration bits” is open, look for the “Extended Instruction Set Enable bit” and

set the configuration to “Enable” at the dropdown list as shown in the next figure.

Be sure that “Configuration Bits set in code” checkbox is not checked. If it is checked, the

developer user must provide explicit configuration in source code level. Please see the

Microchip C18 user’s Manual for more information about Configuration Bits in Source Code.

The other bits can be configured as show in the figure above. This will simulate the hardware

environment established by @Ware ESS v2.5. The relevant configuration bytes are from

address 0x300000 to address 0x300006. As you can see, these addresses are not in the scope


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of CPU program space and they can be set only when the chip is programmed by a device

programmer. Please, refer to PIC18F4550 datasheet for more information.

8.3 Debugger Settings Now, it is required to configure some simulation options in order to properly debug the

application. The most important option is the simulation clock speed. When the application is

executed, the microcontroller’s clock speed may be different than 48MHz, so it is required to

set the proper clock speed. Users can change the clock speed as required. @Ware ESS uses

48MHz clock speed by default when @Ware EduProto III is powered up. See the next figure

that shows how to open the “Simulation Settings” window.

Once “Simulation Setting” window is open, change simulator clock frequency to 48MHz as

shown in the next figure.


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At this point, you are able to simulate and debug your application. If breakpoints are activated

in the source code, you can press the play button at the top bar in the main window. The play

command will rebuild your application if required.

8.4 Timing while application is simulated Timing the application while it is simulated can be used to measure the computation time

required by any portion of the application code. MPLAB SIM provides a Stopwatch for this

purpose. This stopwatch is very easy to use and it behaves like a real life stopwatch. When

application simulation starts, the stopwatch will also start to count the amount of instructions

cycles. See the next figure to show the “Stopwatch” window.


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The stopwatch looks as shown in the next figure. When the stopwatch is shown by first time

and no simulation is in progress, the stopwatch is in reset state. The stopwatch will be

reinitialized when a new simulation starts.

In the next example, a breakpoint is defined. The simulation starts when F9 key is pressed or

play button is clicked. The simulation breaks when a breakpoint is reached and time in

instruction cycles and its equivalent in seconds, milliseconds or microseconds are shown. In

the example below, the first breakpoint reached is at “Delay” function invocation. At that

point, some instruction cycles have been counted because “startup.c” code has been

simulated before “main”.


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From now on, you can press F7 key if you want to debug into the “Delay” function, press F8

key if you want to debug over the “Delay” function, or press F9 key if you want to execute up

to the next breakpoint. The stopwatch can be zeroed from the point you want to measure. See

the next figure that shows the stopwatch in action. In the figure above the simulation is

paused in the breakpoint reached first. The stopwatch also indicates the total instruction

cycles simulated and time in microseconds elapsed.

@ware eduproto iii user guide2

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