Keil MCB251 User Manual

Download

MCS®251 Microcontroller Target Board

for Intel 251SB, Temic 251G1/A1,

and Intel 151 and 8051 Derivatives

User’s Guide 07.97

ii Keil Software

Information in this document is subject to change without notice and does not represent a commitment on the part of the manufacturer. The software described in this document is furnished under license agreement or nondisclosure agreement and may be used or copied only in accordance with the terms of the agreement. It is against the law to copy the software on any medium except as specifically allowed in the license or nondisclosure agreement. The purchaser may make one copy of the software for backup purposes. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or information storage and

retrieval systems, for any purpose other than for the purchaser’s personal use, without written permission.

Keil C51™ and dScope™ are trademarks of Keil Elektronik GmbH.

Microsoft

, MS-DOS®, and Windows™ are trademarks or registered trademarks

of Microsoft Corporation.

, PC®, and PS/2® are registered trademarks of International Business

IBM

Machines Corporation.

, MCS® 51, MCS® 251, ASM-51®, and PL/M-51® are registered

Intel trademarks of Intel Corporation.

Every effort was made to ensure accuracy in this manual and to give appropriate credit to persons, companies, and trademarks referenced herein.

MCB251 Evaluation Board User’s Guide iii

Preface

This manual describes the Keil Software MCB251 Evaluation Board and the

MCS are included:

“Chapter 1. Introduction” gives an overview of this user’s guide and provides a quick start table.

“Chapter 2. Setup” describes how to connect and configure the board and provides detailed information about the DIP switches and configuration jumpers.

“Chapter 3. Hardware” provides detailed information about hardware including the schematic drawings for the MCB251 board, the logic equations for the PLD and the memory locations of the different Monitor versions contained in the EPROM.

“Chapter 4. Programming” gives details about how to use our tools to generate programs for the MCB251 evaluation board.

251 microcontroller software development tools. The following chapters

“Chapter 5. Using the 251 Monitor” gives a quick overview about the MON251 terminal program.

NOTE

This manual assumes that you are familiar with Microsoft Windows and the hardware and instruction set of the 8051 and 251 microcontrollers.

iv Preface

Document Conventions

This document uses the following conventions:

Examples Description

README.TXT

Courier

Variables

Elements that

repeat… Omitted code

. . .



Optional Items

Bold capital text is used for the names of executable programs, data files, source files, environment variables, and commands you enter at the MS-DOS command prompt. This text usually represents commands that you must type in literally. For example:

CLS DIR L251.EXE

Note that you are not required to enter these commands using all capital letters.

Text in this typeface is used to represent information that displays on screen or prints at the printer.

This typeface is also used within the text when discussing or describing command line items.

Text in italics represents information that you must provide. For example,

projectfile

file name. Occasionally, italics are also used to emphasize words in the text.

Ellipses (…) are used to indicate an item that may be repeated.

Vertical ellipses are used in source code listings to indicate that a fragment of the program is omitted. For example:

in a syntax string means that you must supply the actual project

void main (void) { . . . while (1);



Optional arguments in command-line and option fields are indicated by double brackets. For example:

C251 TEST.C PRINT (

{

opt1

opt2

} Text contained within braces, separated by a vertical bar represents a

group of items from which one must be chosen. The braces enclose all of the choices and the vertical bars separate the choices. One item in the list must be selected.

Keys

Text in this sans serif typeface represents actual keys on the keyboard. For example, “Press Enter to continue.”

filename

)

MCB251 Evaluation Board User’s Guide v

Contents

Chapter 1. Introduction..................................................................................... 1

Quick Start.....................................................................................................................2

Chapter 2. Setup................................................................................................. 3

Using the MCB251........................................................................................................4

Configuring the MCB251..............................................................................................5

DIP Switches.................................................................................................................6

Configuration Jumpers..................................................................................................9

CPU Selection.............................................................................................................10

Monitor Modes............................................................................................................11

Monitor Status Display................................................................................................11

Chapter 3. Hardware....................................................................................... 13

Schematics...................................................................................................................18

Printed Board Assembly..............................................................................................22

Technical Data.............................................................................................................23

PAL Equations ............................................................................................................23

Monitor EPROM Addresses........................................................................................26

Chapter 4. Programming................................................................................. 27

Monitor Memory Map.................................................................................................27

Monitor Data & Interrupt Vectors...............................................................................28

Writing Programs for the 251 Monitor........................................................................30

BLINKY Example Program........................................................................................31

External UART Example ............................................................................................46

Chapter 5. Using the 251 Monitor .................................................................. 49

MON251 Terminal Program.......................................................................................49

Index................................................................................................................... 53

vi Contents

MCB251 Evaluation Board User’s Guide 1

Chapter 1. Introduction

Thank you for letting Keil Software provide you with the MCB251 evaluation

board and software for the MCS

251 microcontroller family. With this kit you can generate code and then operate it on the MCB251 evaluation board. This hands-on process helps you determine hardware and software needs for current and future product development.

The MCB251 evaluation board supports all operating modes of the 8051, 151, and 251 microcontrollers and lets you become familiar with the different modes of these devices. You may use a standard 8051 or the Dallas Semiconductor 80C320 or 8xC520 with this board. By generating and testing code for the various operating modes of the 8051, 151, and 251, you can evaluate code and processor performance. These factors can be weighed against other production parameters to help you choose the optimum code and processor combination. Alternatively, you may choose just to play with the board, make it flash the LEDs, and write “Hello World” out the serial port.

This user’s guide describes the hardware of the MCB251 evaluation board and contains the operating instructions for the monitor programs (MON251, MON51) and the terminal programs (MON251.EXE, MON51.EXE). Several different configurations of Monitor 251 and Monitor 51 are installed in the EPROM on the MCB251 board. The monitor programs let you communicate between your PC and the MCB251 evaluation board and let you download and run your 251 or 8051 programs.

The MCB251 kit includes the following items:

n MCB251 Evaluation Board User’s Guide (this manual), n MCB251 Evaluation Board, n MCB251 Evaluation Board Software, n 9-pin Serial Cable, n 9 VDC, 500mA wall adapter power supply, n and a 251 Evaluation Kit which includes a 2K compiler.

2 Chapter 1. Introduction

Quick Start

Use the following list to quickly locate important information about the MCB251 evaluation board.

To… See…

Connect power to the MCB251 board. “Using the MCB251” on page 4. Connect the MCB251 to your PC. “Using the MCB251” on page 4. Read about the default configuration settings. “Configuring the MCB251” on page 5. Create a simple program to blink the LEDs. “BLINKY Example Program” on page 31. Write code to use the external UART. “External UART Example” on page 46. Learn more about the µVision IDE. “Using µVision to Create the BLINKY Program”

on page 32.

Learn more about the dScope debugger. “Using dScope to Debug the BLINKY Program”

on page 42.

Learn about the MON251 terminal program. “Chapter 5. Using the 251 Monitor” on page 49. Read about the DIP switch settings. “DIP Switches” on page 6. Read about the configuration jumpers. “Configuration Jumpers” on page 9. Configure the RAM/ROM memory. “Monitor Memory Map” on page 27. See the MCB251 schematics. “Schematics” on page 18. See the MCB251 PAL equations. “PAL Equations” on page 23.

MCB251 Evaluation Board User’s Guide 3

Chapter 2. Setup

The MCB251 evaluation board requires power and a serial connection to a PC running the MON251 terminal program. Before you start, make sure you have satisfied the following hardware and software requirements.

Hardware Requirements

n The MCB251 Evaluation Board. n A serial cable, 9-pin male to 9-pin female, 1-2 meters long, wired one-to-one. n A PC with an available RS-232 port. If the port has a 25-pin connector, a

9-pin male to 25-pin female adapter may be required.

n A device programmer is required to program any EPROMs or other

programmable devices.

Software Requirements

n The Keil MON251 terminal program (MON251.EXE) or the Keil dScope for

Windows with the MON251.DLL driver. The Keil MON251 software/firmware is already programmed into the EPROM provided on the MCB251 board.

n Microsoft Windows version 3.1, 3.11, Windows 95, or Windows NT.

4 Chapter 2. Setup

Using the MCB251

To use the MCB251 evaluation board, you must:

n Connect the external serial port jack (EXT RS232) to a serial port on your PC

using the supplied serial cable.

n Connect power using a power supply provided.

The serial cable lets your PC download program code and debug your target applications. The power cable provides power to the MCB251 evaluation board. The MCB251 does not get power from the PC via the serial cable.

The following illustration shows MCB251 board and the important interface and hardware components.

Prototyping

Area

Bus

Signals

Configuration

Jumpers

Port

Signals

Intel 251SB / Temic 251G1

Dallas 320 or Standard 8051

Monitor EPROM

Port 1 Status

LED’s

DIP Switches

251 on-chip Serial Jack

External Serial Jack

Interrupt Button

Reset Button Power

Supply

Socket for Temic 251A1

MCB251 Evaluation Board User’s Guide 5

Configuring the MCB251

You configure the MCB251 evaluation board with the DIP switches and the configuration jumpers. The MCB251 evaluation board is shipped with the following configuration:

n Intel 87C251SB or Temic 251G1 microcontroller, n Source Mode with 0 Wait States, n Non-Page Mode.

The default DIP switch settings are shown in the following table.

Switch Uart

Int

ON X X X X X X

OFF X X X X

ext

Uart

SRC/D2Page Moni

tor

51/

MAP1MAP2LED A17

151

The default settings of the configuration jumpers are shown in the following figure. The NONP jumper selects the Non-Page Mode of the 251 CPU. The INT1 and NMI jumpers are set to connect the Interrupt Button to the INT1 source.

6 Chapter 2. Setup

DIP Switches

The following sections describe each of the DIP switches of the MCB251 board.

Uart_INT: Default ON

The Uart_INT switch selects whether or not the external 16550 UART generates an interrupt on the microcontroller. If Uart_INT is ON, the interrupt output from the 16550 is connected to port pin 3.2. If Uart_INT is OFF, the interrupt output from the 16550 is not connected to the microcontroller. This switch is useful when using interrupt-driven serial I/O with the external UART. You must set Uart_INT to ON, if you want to halt execution of a user program within dScope.

ext_Uart : Default ON

The ext_Uart switch determines whether or not the chip select signal for the external 16550 UART is generated. If ext_Uart is ON, the chip select signal is generated and the Monitor program uses the external serial interface for communication. The communication baud rate is 57600 BPS. If ext_Uart is OFF, the UART chip select is not generated and the Monitor program uses the on-chip serial interface for communication. In this case, the communication baud rate is 19200 BPS.

SRC/D2: Default ON

The SRC/D2 switch selects either SOURCE mode or BINARY mode on the 251 CPU. If SRC/D2 is ON, SOURCE mode is selected. If SRC/D2 is OFF, BINARY mode is selected.

When you use a 151 or 8051 device, the SRC/D2 must be OFF. When you use the Dallas 320/520 device, the SRC/D2 must be ON to select a Monitor version

which supports the Dual DPTR registers of that CPU. Refer to “CPU Selection” on page 10 for a complete description on how to select the CPU type and the related Monitor version

If you operate the MCB251 with a user application in EPROM, you must set the SRC/DP2 switch to OFF.

MCB251 Evaluation Board User’s Guide 7

PAGE: Default OFF

The PAGE switch selects whether or not the 251 or 151 Monitor operates in page mode or non-page mode. When PAGE is ON, a page mode Monitor version is selected. When PAGE is OFF, a non-page mode Monitor version is enabled. For correct operation of the MCB251 board, you must also set the configuration jumpers to the correct position: PAGE for page mode or NONP for non-page mode.

If you operate the MCB251 with a user application in EPROM, you must set the PAGE switch OFF. However, you may still use the jumpers to select page mode or non-page mode.

Monitor: Default ON

The Monitor switch selects if the Monitor is used for debugging or if the MCB251 operates with a user application EPROM at IC13. When Monitor is ON, the Monitor Memory Mapping is enabled and you must operate the MCB251 board with the supplied Monitor EPROM. When Monitor is OFF, the User Memory Mapping is selected and you may insert an EPROM with your target application.

If you operate the MCB251 with a user application EPROM, you must set the DIP switches 51/151, PAGE and SRC/D2 to OFF.

51/151: Default ON

The 51/151 switch selects whether a 251 or a 151/8051 compatible microcontroller is installed in the IC1 socket. If a 151/8051 compatible device is installed, 51/151 should be ON. If a 251 compatible device is installed, 51/151 should be OFF (unless the 251 is emulating an 8051 or 151 device).

A17: Default ON

The A17 switch selects whether the 251 CPU uses P1.7 as the A17 address line or whether P1.7 is used as I/O port line. When A17 is ON, the A17 line is used and you can address up to 256KB memory with the 251 device. When A17 is OFF P1.7 can be used as I/O port line. Note that the CONFIG BYTES of the 251 CPU must be programmed correctly to use this feature.

8 Chapter 2. Setup

The Monitor EPROM which is supplied in the MCB251 board is configured for 256KB memory. Refer to the 251 or 151 Microcontroller User’s Manual for more information.

If you use the MCB251 board with an 8051 compatible device, such as the Intel 151 or Dallas 320, the A17 DIP switch must be OFF.

MAP1, MAP0: Default OFF, OFF

The MAP1 and MAP0 switches select the memory map for the MCB251. The memory map used on the MCB251 board depends on the setting of the Monitor DIP switch. The memory for both settings are shown in the following tables.

Monitor Memory Mapping (Monitor DIP Switch is ON)

Map1 Map0 RAM Monitor EPROM UART CS & USER CS

OFF OFF

251 Mode

OFF ON illegal illegal illegal

ON OFF illegal illegal illegal ON ON

8051 Mode

00:0000h–01: FFFFh

FE:0000h–FF: DFFFh

X:0000h–X:DFFFh C:0000h-C:DFFFh

(von Neumann mapped)

FF:E800h–FF:FFFFh UART: FF:E400h–FF:E7FFh

USER: FF:E000h–FF:E3FFh

C:E800h–C:FFFFh UART: X:E400h–X:E7FFh

USER: X:E000h–X:E3FFh

(von Neumann mapped)

User Memory Mapping (Monitor DIP Switch is OFF)

Note: DIP Switch 51/151, Page and SRC/D2 must be also OFF

Map1 Map0 RAM User EPROM UART CS & USER CS

OFF OFF

251 Mode

OFF ON

251 Mode

ON OFF

251 Mode

ON ON

8051 Mode

00:0000h–01:FFFFh

FE:0000h–FE:FFFFh

00:0000h–01:FFFFh FE:0000h–FF:DFFFh

00:0000h–00:7FFFh 00:8000h–01:FFFFh

X:0000h–X:DFFFh C:0000h–C:FFFFh UART: X:E400h–X:E7FFh

FF:0000h–FF:DFFFh FF:E800h–FF:FFFFh

FF:E800h–FF:FFFFh

FE:0000h–FF:DFFFh FF:E800h–FF:FFFFh

UART: FF:E400h–FF:E7FFh USER: FF:E000h–FF:E3FFh

USER: X:E000h–X:E3FFh

LED: Default ON

The LED switch selects whether or not Port 1 is connected to the 8 LEDs in the upper right portion of the board. When LED is ON, the LEDs on port 1 are enabled. When LED is OFF, the LEDs are not connected to port 1. If the Monitor DIP switch ON and LED is OFF, the Monitor does not modify the port 1 lines on power-up.

MCB251 Evaluation Board User’s Guide 9

Configuration Jumpers

The following sections describe each of the configuration jumpers of the MCB251 board.

NMI: Default ON

The NMI configuration jumper selects whether or not the INT push-button is connected to the NMI pin on the Temic 251G1 microcontroller. If NMI is OFF, the INT push-button is connected to the NMI pin on the Temic 251G1. If NMI is ON, pin 34 is connected to GND.

INT1: Default ON

The INT1 configuration jumper selects whether or not the INT push-button is connected to port pin 3.3 on the microcontroller. If the INT1 switch is ON, the INT push-button is connected to port 3.3. If INT1 is OFF, the INT push-button is not connected to port 3.3.

PAGE / NONP: Default NONP

These nine configuration jumpers select whether the MCB251 board operates in page mode or non-page mode. When these jumpers are in the PAGE position, the address/data bus is configured for 251/151 page mode. When the jumpers are in the NONP position, the standard 8051 bus or 251/151 non-page mode is selected.

In page mode the data and upper address byte are multiplexed on port 2 (this mode is available only on the 251/151). In non-page mode the data and lower address byte are multiplexed on port 0 (this mode is available on the 251, 151, and 8051). This jumper setting should be set to coincide with the CPU CONFIG BYTE settings. Refer to the 251 or 151 Microcontroller User’s Manual for more information about these modes.

10 Chapter 2. Setup

CPU Selection

The MCB251 board can operate with various CPU types. The following table gives you an overview of the various CPU operating modes. It lists values for the configuration bytes of the 251 / 151 CPU used by the Monitor program. For more information about the configuration registers, refer to the 251 or 151 Microcontroller User’s Manual.

NOTE

The settings in the following table are only relevant only for the Monitor EPROM (Monitor DIP switch ON). When the Monitor DIP switch is OFF, you may select the Memory Mapping and the CPU type with the MAP0 and MAP1 DIP switches.

CPU Type DIP Switch Setting CPU Config Bytes

and Operating Mode Page Src/D2 Map0 Map1 A17 Config0 Config1

251SB, 251G1 or 251A1

Page Mode, Source Mode

251SB, 251G1 or 251A1

Page Mode, Binary Mode

251SB, 251G1 or 251A1

Non-page Mode, Source Mode

251SB, 251G1 or 251A1

Non-page Mode, Binary Mode

Intel 151, Page Mode ON OFF ON ON OFF 0FCh 0E7h

Intel 151, Non-page Mode OFF OFF ON ON OFF 0FEh 0E7h

Standard 8051 Derivatives OFF OFF ON ON OFF N/A N/A

Dallas 320/520 OFF ON ON ON OFF N/A N/A

ON ON OFF OFF ON 0F1h 097h

ON OFF OFF OFF ON 0F0h 097h

OFF ON OFF OFF ON 0F3h 097h

OFF OFF OFF OFF ON 0F2h 097h

NOTE

The Temic 251A1 and 251G1 are currently available only as A-step devices. The operating mode of this device is programmed inside the CPU and cannot be changed in an external EPROM. If you use one of these devices you must set the PAGE DIP switch OFF and the SRC/D2 DIP switch ON. This restriction does not apply when the 251A1 and 251G1 are available in C-step technology.

The Intel 251SB CPU may be used to emulate the Intel 151 CPU. This lets you test 151 applications without replacing the 251SB CPU.

MCB251 Evaluation Board User’s Guide 11

Monitor Modes

The MCB251 board comes with a Monitor EPROM which contains several different Monitor configurations. Most of the Monitor configurations are required to run the different CPU types on the board. The following Monitor settings are independent of the CPU type used in the MCB251 board.

DIP Switch Monitor Mode

ext_Uart ON: use EXT RS232 interface @ 57600 BPS. for Monitor communication.

OFF: use INT RS232 interface @ 19200 BPS. for Monitor communication.

LED ON: display Monitor status on Port 1 LED’s (see below).

OFF: Monitor status is not displayed and Port 1 is not affected.

Monitor ON: use Monitor program for debugging

OFF: User EPROM as IC13. Refer to “MAP1 and MAP0 DIP Switch” on

page 7 to for the User EPROM Memory Map.

NOTE

Some derivatives of the 8051 and 251 microcontroller family do not have a compatible serial interface or baud rate generator for the internal serial interface. For such devices it is impossible to use the INT RS232 interface. Currently, the Temic 251A1 and standard 8051 CPU are not compatible. With these devices you can only use the Monitor with the EXT RS232 interface—the

ext_Uart DIP switch must be ON.

Monitor Status Display

During the reset phase the Monitor program displays status information on the Port 1 LEDs. This status information reflects the board configuration and signals that the board is working correctly. The status byte is shifted to the left, which

flashes LED’s during the reset phase. The following table lists the first phase of the LED pattern.

Monitor Version P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0

Monitor 251 and 251 CPU A17 OFF OFF OFF OFF OFF OFF ON† Monitor 51 for 151 or 8051 CPU – ON ON ON ON ON ON ON† Monitor 51 for Dallas 320/520 – ON OFF ON OFF ON OFF ON†

† The P1.0 status LED is ON when the INT RS232 interface is used for the Monitor/PC interface

and OFF when the EXT RS232 interface is used for the Monitor/PC interface.

12 Chapter 2. Setup

MCB251 Evaluation Board User’s Guide 13

Chapter 3. Hardware

The MCB251 is designed to be a very flexible evaluation board that you can use to compare the effectiveness of the 251 versus the 8051. We have attempted to support all features of the 251 while remaining compatible with the 8051. We have also tried to provide a board that can be expanded to support your own hardware prototypes.

This chapter describes logical sections of the MCB251 and also provides a circuit description. The descriptions here will help you understand how the MCB251 board works and how you can easily interface to the various I/O devices available.

The following block diagram shows the various memory, I/O, configuration, and power systems that compose the board.

MemorySystem

Input

8-12VDC

Confi

Power

Suppl

RAM EPROM UART

Buffers

Internal

uration

Output

5V +/-5%

400mA

Serial I

251/8051

CPU

Buffer

User I

EXT RS232

INT RS232

Bus & Port

Reset & Int.

P1 LEDs

nals

Power Supply

Power is supplied to the MCB251 from an external 8-12 Volt DC power supply which is capable of providing 300-500mA. Connection is made using a standard

14 Chapter 3. Hardware

5.5mm barrel plug with a 2.5mm center hole. The center hole provides positive voltage. 5 Volts DC is generated and provided to the board by a 7805 voltage regulator at IC2. To reduce the noise for the 251A1 A/D converter a second 78L05 voltage regulator is provided at IC6.

251/8051 CPU

The Intel 251SB or Temic 251G1 provided with the MCB251 are 251 derivatives with 1 Kbytes of internal RAM. The CPU is located at IC1. The IC1 socket can accommodate a Dallas 320 or 520 CPU, an Intel 151, or a standard 8051 microcontroller.

You may use the Temic 251A1 CPU in the IC4 socket. However, you must remove the CPU in socket IC1 when you use the 251A1.

A 12.000 MHz crystal provides the clock signal for the CPU.

NOTE

You may insert only one CPU into the board at a time. It is not possible to operate with a Temic 251A1 in socket IC4 and another 251/8051 CPU in socket IC1 simultaneously.

Configuration

The MCB251 is a very flexible evaluation board. You can change the operation of the board using the DIP switches and the configuration jumpers. Features such as CPU type, LEDs, page mode, memory map, push button inputs, external UART interrupts, and on-chip serial port can all be configured using these switches.

NOTE

You must RESET the MCB251 after changing the state of any DIP switch.

Refer to “DIP Switches” on page 6 and “Configuration Jumpers” on page 9 for a complete description of the DIP switches and configuration jumpers.

Buffers

The MCB251 provides complete support for 251 page mode and non-page mode. To do this, the MCB251 includes 2 latches for the data/address bus.

MCB251 Evaluation Board User’s Guide 15

In non-page mode, the 251/151 multiplexes the address bus (A0-A7) and data bus (D0-D7) on port 0. This is the same way the standard 8051 works. To support non-page mode, the configuration jumpers must be in the NONP position. In non-page mode, the address bus (port 0) is latched using the 74HC373 at IC8.

In page mode, the 251/151 multiplexes the address bus (A8-A15) and data bus (D0-D7) on port 2. To support page mode, the configuration jumpers must be in the PAGE position. In page mode, the address bus (port 2) is latched using the 74HC373 at IC15.

NOTE

The CPU configuration bytes must be set according the board configuration for page or non-page mode. Refer to the 251/151 data book for more information about the CPU configuration bytes. The Monitor EPROM contains pre-configured Monitor versions for page and non-page mode. These are selected with the PAGE DIP switch. To select a Monitor version for PAGE mode, the PAGE DIP switch must be ON.

Decode Logic

All memory address decode logic and other signal conversions are performed by the 20V8 PAL at IC12. Refer to “ PAL Equations” on page 23 for a complete

listing of the PAL equations used.

Memory and I/O Devices

The MCB251 maps three memory devices into the address space of the CPU: the RAM at IC14, the RAM at IC15, and the EPROM at IC13. The 20V8 PAL at IC12 provides the chip select signal for the external UART at IC5 and a user chip select signal.

The MCB251 board comes with a Monitor EPROM at IC13 which can support up to 16 different Monitor versions. You may replace the Monitor EPROM at IC14 with a 27C1001 or 27C2001 for your target program. If you insert an EPROM with a user application program the DIP switches PAGE, SCR/D2, 51/151, and Monitor must be set to OFF. If the Monitor DIP switch is OFF, you may select different memory maps for the user application using the MAP0 and MAP1 DIP switches. For more information refer to the MAP1 and MAP0 DIP switch descriptions on page 7.

16 Chapter 3. Hardware

Status LEDs

The MCB251 has a single power LED labeled ON which indicates the power to the board is on. Eight LEDs are optionally connected to the Port 1 outputs through a 74HC373 at IC3. The Port 1 LEDs are flashed during reset and display the configuration status of the Monitor EPROM. For more information

refer to “Monitor Status Display” on page 11. You may disable the LED driver by setting the LED DIP switch OFF. The this DIP switch is OFF, the Monitor does not affect the Port 1 Pins during the reset phase.

Push Buttons

The MCB251 provides two push buttons. The first push button, labeled RESET (S1), is connected to the reset input of the CPU. The second button, labeled INT (S2), is connected to the INT1 (port 3.3) of the CPU when the configuration jumper INT1 (J5) is set. When the configuration jumper NMI is not set, you may generate an NMI signal to the Temic 251G1 device.

Serial Port

The MCB251 supports both the on-chip serial port and an external UART. Both use the MAX232, at IC10, to convert TTL to RS-232 voltage levels.

You can configure the Monitor to use either the on-chip serial port or the external UART for the communication with the PC. When the ext_Uart DIP switch is ON, the external UART is used at 57600 BPS for the Monitor communication. Otherwise the on-chip serial port is used at 19200 BPS for the Monitor communication.

The internal serial port is derived from the internal serial functions of the 8051/251 (P3.0/RXD and P3.1/TXD).

The external UART (IC5) is implemented using an 8250, 16450, or 16550 device. This is the same chip that is used in most PCs. A 1.8432 MHz oscillator provides the input frequency to the UART. The interrupt output of the UART is optionally connected to the INT0 pin (port 3.2) of the CPU. When the Uart_INT DIP switch is ON, the UART interrupt is connected to the INT0 CPU pin.

MCB251 Evaluation Board User’s Guide 17

Both serial ports are configured as a standard 3-wire interface. The handshaking signals are connected to loop the PC’s

signals back. Refer to the figure at the right to determine how the DB9 connector for this port is wired.

Prototyping Area

A perforated area is provided on the MCB251 for prototyping your own hardware. All CPU signals necessary to create a 40-pin DIP plug for emulating an 8051 or 251 in a 40-pin DIP package are connected to this prototyping area. In addition, the data and address bus signals and the user chip select signal are connected to this area. The signals provided are driven directly by the CPU. Exercise caution to avoid overloading these signal lines. Refer to “DIP Switches” on page 6 for the pin-out of the CPU and bus signals.

NOTE

Since the MCB251 supports both the page mode and non-page mode you should connect memory-mapped devices directly to the data bus DB0-DB7 and A0-A15.

18 Chapter 3. Hardware

Schematics

MCB251 Evaluation Board User’s Guide 19

20 Chapter 3. Hardware

MCB251 Evaluation Board User’s Guide 21

22 Chapter 3. Hardware

Printed Board Assembly

MCB251 Evaluation Board User’s Guide 23

Technical Data

Supply Voltage: 8V-12V DC

Supply Current: typical: 300mA

System Clock: 12 MHz

Memory: 256 Kbytes RAM

128 Kbytes Monitor EPROM (optional: 256 Kbytes User EPROM)

CPU: Intel 80C251SB or Temic 80C251G1

(optional: Dallas 80C320, Intel 80C151, Intel 80C51FC, or compatible device)

Peripherals: 2 × RS232 Interfaces

PAL Equations

This following lists the PAL equations for the 20V8 logic device at IC12.

;PALASM Design Description

;---------------------------------- Declaration Segment -----------TITLE GAL for MCB251SB Prototype board PATTERN Decoder and Boot Logic REVISION 1.0 AUTHOR Hans Schneebauer COMPANY Keil Elektonik GmbH DATE 10/06/96

CHIP IC6 PALCE20V8

;---------------------------------- PIN Declarations --------------PIN 1 LED COMBINATORIAL ; INPUT PIN 2 RST COMBINATORIAL ; INPUT PIN 3 /PSEN COMBINATORIAL ; INPUT PIN 4..11 A[10..17] COMBINATORIAL ; INPUT PIN 12 GND ; INPUT PIN 13 /MAP[0] COMBINATORIAL ; INPUT PIN 14 /MON_ON COMBINATORIAL ; INPUT PIN 15 /RD_RAM COMBINATORIAL ; OUTPUT PIN 16 MON_RUN COMBINATORIAL ; OUTPUT PIN 17 /CS_USER COMBINATORIAL ; OUTPUT PIN 18 A16_ROM COMBINATORIAL ; OUTPUT PIN 19 A16_RAM COMBINATORIAL ; OUTPUT PIN 20 /CS_UART COMBINATORIAL ; OUTPUT PIN 21 /CS_ROM COMBINATORIAL ; OUTPUT PIN 22 CS_RAM COMBINATORIAL ; OUTPUT PIN 23 /MAP[1] COMBINATORIAL ; INPUT PIN 24 VCC ; INPUT

24 Chapter 3. Hardware

;----------------------------------- Boolean Equation Segment -----EQUATIONS

IF (MON_ON) THEN ; Monitor switched on BEGIN A16_ROM = LED IF (MAP[1..0] = #b11) THEN BEGIN RD_RAM = PSEN + /A[16] ; 8051 Mode A16_RAM = 0; END ELSE BEGIN RD_RAM = PSEN A16_RAM = A[16] END IF (MON_RUN) THEN BEGIN MON_RUN = /RST IF (MAP[1..0] = #b11) THEN ; 8051 Mode ? BEGIN CS_RAM = /(A[15] * A[14] * A[13]) ; Address 0 - dfff END ELSE BEGIN CS_RAM = /(A[17] * A[16] * A[15] * A[14] * A[13]) ; Address 0 - 3dfff END

CS_ROM = A[17] * A[16] * A[15] * A[14] * ; Address 3e800 - 3efff A[13] * /A[12] * A[11] + A[17] * A[16] * A[15] * A[14] * ; Address 3f000 - 3ffff A[13] * A[12] END ELSE BEGIN CS_ROM = 1 ; ROM always enabled CS_RAM = 0 ; RAM always disabled IF (A[17..10] = #b11111010) THEN ; Address 3e800 - 3ebff BEGIN MON_RUN = PSEN * /RST END ELSE BEGIN MON_RUN = 0 END END END ELSE ; Monitor switched off BEGIN CASE (MAP[1..0]) BEGIN 0: BEGIN CS_RAM =/(A[17] * A[16]) ; RAM 00000 - 2ffff CS_ROM = A[17] * A[16] * /CS_UART * /CS_USER ; ROM 30000 - 3dfff A16_ROM = A[16] A16_RAM = A[16] RD_RAM = PSEN END 1: BEGIN CS_RAM = /A[17] ; RAM 00000 - 1ffff CS_ROM = A[17] * /CS_UART * /CS_USER ; ROM 20000 - 3dfff A16_ROM = A[16] A16_RAM = A[16] RD_RAM = PSEN END 2: BEGIN CS_RAM = /A[17] * /A[16] * /A[15] ; RAM 0000 - 07FFF CS_ROM = /CS_RAM * /CS_UART * /CS_USER ; ROM 00000 - 3ffff

MCB251 Evaluation Board User’s Guide 25

A16_ROM = A[16] A16_RAM = A[16] RD_RAM = PSEN END 3: BEGIN ; 8051 Mode CS_RAM = /(A[15] * A[14] * A[13]) ; RAM 00000 - 0dfff 8051 Mode CS_ROM = 1; ; ROM 00000 - 0ffff A16_ROM = 0 A16_RAM = 0 RD_RAM = /A[16] END END

END

IF (MAP[1..0] = #b11) THEN ; 8051 Mode? BEGIN IF (A[15..10] = #b111000) THEN ; ADDRESS e000 - e3ff BEGIN CS_USER = 1 END ELSE BEGIN CS_USER = 0 END

IF (A[15..10] = #b111001) THEN ; ADDRESS e400 - e7ff BEGIN CS_UART = 1 END ELSE BEGIN CS_UART = 0 END END ELSE BEGIN IF (A[17..10] = #b11111000) THEN ; ADDRESS 3e000 - 3e3ff BEGIN CS_USER = 1 END ELSE BEGIN CS_USER = 0 END

IF (A[17..10] = #b11111001) THEN ; ADDRESS 3e400 - 3e7ff BEGIN CS_UART = 1 END ELSE BEGIN CS_UART = 0 END END

;-------------------------------------------------------------------

26 Chapter 3. Hardware

Monitor EPROM Addresses

This following table lists the EPROM addresses in the Monitor EPROM for the different monitor versions and contains the EPROM addresses of the 251/151 configuration bytes CONFIG0 and CONFIG1. At address 0 and address 10000H the Monitor EPROM contains a LJMP 0E800H instruction.

Monitor Version EPROM Addresses

Monitor Program Code CONFIG0 CONFIG1

8051/151 Monitor, PAGE Mode with Flash LED’s

251 Monitor, Source Mode, PAGE, with Flash LED's

8051/151 Monitor, PAGE Mode with Flash LED's

251 Monitor, Binary Mode, PAGE, with Flash LED's

8051 Monitor, Dallas 320 Version with Flash LED's251

251 Monitor, Source Mode, NOPAGE, with Flash LED's

8051/151 Monitor, NOPAGE, with Flash LED's

251 Monitor, Binary Mode, NOPAGE, with Flash LED's

8051/151 Monitor, PAGE Mode no Flash LED's

251 Monitor, Source Mode, PAGE, no Flash LED's

8051/151 Monitor, PAGE Mode no Flash LED's

251 Monitor, Binary Mode, PAGE, no Flash LED's

8051 Monitor, Dallas 320 Version, no Flash LED's251

251 Monitor, Source Mode, NOPAGE, no Flash LED's

8051/151 Monitor, NOPAGE, no Flash LED's

251 Monitor, Binary Mode, NOPAGE, no Flash LED's

00800H – 01FFFH 01FF8H 01FF9H

02800H – 03FFFH 03FF8H 03FF9H

04800H – 05FFFH 05FF8H 05FF9H

06800H – 07FFFH 07FF8H 07FF9H

08800H – 09FFFH – –

0A800H – 0BFFFH 0BFF8H 0BFF9H

0C800H – 0DFFFH 0DFF8H 0DFF9H

0E800H – 0FFFFH 0FFF8H 0FFF9H

10800H – 11FFFH 11FF8H 11FF9H

12800H – 13FFFH 13FF8H 13FF9H

14800H – 15FFFH 15FF8H 15FF9H

16800H – 17FFFH 17FF8H 17FF9H

18800H – 19FFFH – –

1A800H – 1BFFFH 1BFF8H 1BFF9H

1C800H – 1DFFFH 1DFF8H 1DFF9H

1E800H – 1FFFFH 1FFF8H 1FFF9H

MCB251 Evaluation Board User’s Guide 27

Chapter 4. Programming

Writing programs for the MCB251 is relatively simple. However, before you get started, there are a few points you should keep in mind.

n The 251 supports a new hardware architecture that is different from that of

the 8051. The 251 begins executing instructions at address 0FF0000h. The MCB251 is shipped with the Keil 251 monitor programmed into an EPROM on the MCB251 board. The MCB251 board has Monitor boot logic which is coded in the PLD device. At Reset the Monitor EPROM is addressable at address 0FF0000h. After the execution of the first Monitor instruction, the Monitor EPROM is addressed at 0FFE800h-0FFFFFFh.

n If you use the monitor for loading and running programs via the serial port on

the MCB251, your programs still start at address 0FF0000h or C:0000. This is the same address as if you do not use a monitor program.

This following sections provide more information about writing programs for the MCB251 evaluation board.

Monitor Memory Map

The MCB251 evaluation board supports 248KB RAM memory which is addressable by for user application programs. The memory map depends on how you use the A17 address line. Refer to the 251 Microcontroller User’s Manual for more information about the memory map of the 251 CPU.

Monitor Memory Mapping (Monitor DIP Switch is ON)

Map1 Map0 RAM Monitor EPROM UART CS & USER CS

OFF OFF

251 Mode

OFF ON illegal illegal illegal

ON OFF illegal illegal illegal

ON ON

8051 Mode

The 251 CPU provided with the MCB251 evaluation board is programmed so that the RD# signal provides the A16 address line. This lets the 251 address up to 256K of external address space. The memory mapping during the test phase allows you to use the maximum address space of that CPU.

00:0000h–01: FFFFh

FE:0000h–FF: DFFFh

X:0000h–X:DFFFh C:0000h-C:DFFFh

(von Neumann mapped)

FF:E800h–FF:FFFFh UART: FF:E400h–FF:E7FFh

USER: FF:E000h–FF:E3FFh

C:E800h–C:FFFFh UART: X:E400h–X:E7FFh

USER: X:E000h–X:E3FFh

(von Neumann mapped)

28 Chapter 4. Programming

Monitor Data & Interrupt Vectors

The Monitors provided with the MCB251 use a minimal amount of your target’s resources. The following sections describe what is required for the 251 monitor and for the 8051 monitor.

Monitor 251

For debugging, the 251 monitor uses the TRAP interrupt vector of the 251 CPU for handling breakpoints. In addition, you can enable the serial interrupt so that you can use dScope to halt a program that is running. The Temic 251G1 allows you to stop program execution with the NMI interrupt. The interrupt vector addresses listed in the following table should not be used by the application under test.

The 251 monitor uses the address space 0xFFDFC0-0xFFDFFF for monitor data. The user application should not modify these locations. Other than the interrupt vectors and the monitor data, the monitor program does not use and other memory resources of the 251 CPU.

You must reserve the following address spaces with the L251 linker RESERVE directive. When you reserve these memory areas, the linker prevents your target program from using them.

Monitor Data Space and Interrupt Vectors Monitor Mode Interrupt Vectors Monitor Data

Serial Interrupt disabled TRAP: FF:007Bh–FF:007Dh,

NMI: FF:003Bh–FF:003Dh

EXT RS232 Serial Interrupt enabled

INT RS232 Serial Interrupt enabled

INT0: FF:0003h–FF:0005h NMI: FF:003Bh–FF:003Dh TRAP: FF:007Bh–FF:007Dh

SINT: FF:0023h–FF:0025h NMI: FF:003Bh–FF:003Dh TRAP: FF:007Bh–FF:007Dh

FF:DFC0h–FF:DFFFh

MCB251 Evaluation Board User’s Guide 29

Monitor 51

The 8051 monitor does not require the use of any interrupt vectors. The serial interrupt is not required for serial communication. However, if you enable the serial interrupt, you must reserve the interrupt vector space for the internal interrupt 0 or serial interrupt.

The 8051 monitor uses the address space X:0xDF00-X:0xDFFF for monitor

data. If you enable “Record Trace”, then the address space X:0xCC00-X:0xDFFF is used for monitor data. The complete CODE/XDATA space is von-Neumann wired so that accesses to the XDATA space modify the data in the CODE space.

30 Chapter 4. Programming

Writing Programs for the 251 Monitor

Compiling and linking programs for use with the 251 monitor on the MCB251 board requires only two steps.

First, compile your applications as you normally would. Make sure that you have selected the correct mode (MODBIN or MODSRC) directive to specify 251 operating mode you have configured on the MCB251 board. For example, you may use the following command line.

C251 MYCODE.C MODSRC

Second, link your object files using the CLASSES directive shown in the following example command line.

L251 MYCODE.OBJ RESERVE (0FF0003H-0FF0005H, 0FF003BH-0FF003DH, 0FF007BH-0FF007DH)

In this command line, the RESERVE directive tells the linker not to use the specified address space for the user application.

NOTE

The only difference between writing programs for the Monitor 251 compared to other user applications is the RESERVE directive for the L251 linker. However, you can still use the RESERVE directive, if you want to program your application into an EPROM.

You may use the OH251 utility to create an Intel HEX file from the absolute object module created by the linker. Use the following command line to create a HEX file:

OH251 MYFILE

You may use either Intel HEX files or absolute object modules with the dScope debugger and the MON251 terminal program. Absolute object modules include source-level debugging information but HEX files do not.

MCB251 Evaluation Board User’s Guide 31

BLINKY Example Program

The following simple program, BLINKY, is an exercise you may use to test the MCB251 and verify that you can use the tools provided to generate a working program.

BLINKY blinks the LEDs on the MCB251 evaluation board. The complete source listing for the program is shown below:

/* BLINKY.C - LED Flasher for the Keil MCB251 Evaluation Board */

#include <reg251s.h> /* Include 251SB header file */

void wait (void) { /* wait function */ ; /* only to delay for LED flashes */ }

void main (void) { unsigned int i; /* Delay var */ unsigned char j; /* LED var */

while (1) { /* Loop forever */ for (j=0x01; j< 0x40; j<<=1) { /* Blink LED 0, 1, 2, 3, 4, 5, 6 */ P1 &= 0x80; /* do not change A17 port line */ P1 |= j; /* Output to LED Port */ for (i = 0; i < 10000; i++) { /* Delay for 1000 Counts */ wait (); /* call wait function */ } }

for (j=0x40; j> 0x01; j>>=1) { /* Blink LED 6, 5, 4, 3, 2, 1 */ P1 &= 0x80; /* do not change A17 port line */ P1 |= j; /* Output to LED Port */ for (i = 0; i < 10000; i++) { /* Delay for 10000 Counts */ wait (); /* call wait function */ } } } }

You may build the BLINKY example program either using the 251 tools from the MS-DOS command line or you may use the µVision integrated development

environment and dScope. Both methods are described below.

32 Chapter 4. Programming

Using the MS-DOS Command Line Tools

Use the following command line to compile the BLINKY example program:

C251 BLINKY.C DEBUG MODSRC

Use the following command line to link the BLINKY example program for use with the 251 monitor:

L251 BLINKY.OBJ RESERVE (0FF0003H-0FF0005H, 0FF003BH-0FF003DH, 0FF007BH-0FF007DH)

Using the Windows-Based Tools

This section leads you step-by-step through the process of creating the BLINKY

example program and testing it using the µVision IDE and dScope debugger.

Using µVision to Create the BLINKY Program

To create the BLINKY example program using µVision, you need to perform the following steps:

n Create the BLINKY.C source file. n Create the BLINKY project file. n Include BLINKY.C in the project. n Set the C251 compiler options for the project. n Set the L251 linker options for the project. n Set the path specifications for the 251 tools (if necessary). n Set the make options for the project. n Build the project.

Each of these steps is described in detail below.

MCB251 Evaluation Board User’s Guide 33

Create the BLINKY.C Source File

Start µVision by double-clicking on the icon in the 251 Tools group.

µVision Program Icon

When µVision starts, select the New command from the File menu and µVision opens a new text window in which you may create the BLINKY program.

Enter the BLINKY example program shown on page 31. Your screen should look something like the following figure.

34 Chapter 4. Programming

You should save the BLINKY program after you enter it. Select the Save As… command from the File menu and µVision displays the Save As dialog box shown below.

To save the program as BLINKY.C, enter BLINKY.C in the File Name text box at the top of the Save As dialog box. You may want to save the flash program and the other files you create in a separate directory. This example uses C:\BLINKY for the source files and project files.

MCB251 Evaluation Board User’s Guide 35

Create the BLINKY Project File

After you save BLINKY.C, you should create a BLINKY project file. A project file contains a list of all the source files in your project as well as the options to use for the compiler, assembler, linker, and make facility. Additionally, the project manager helps you compile, link, and test your target program.

To create a project file for BLINKY, select the New Project… command from

the Project menu. µVision displays the dialog box shown below. Enter the name for the project in the File Name text box. This example uses BLINKY.PRJ.

NOTE Always use PRJ as the file extension for project files.

36 Chapter 4. Programming

Include BLINKY.C in the Project

When the project file is created, µVision displays the Project Manager dialog box. Here, you select the source files to include in your project.

Click the Insert button and choose the BLINKY.C file you previously saved. Then, click the save button to save your changes to the project file. To return to the Project Manager dialog box, select the Edit Project… command from the Project menu.

When you have created a project file and inserted the source files into the project, you are ready to set the options for the compiler, linker, and other tools.

MCB251 Evaluation Board User’s Guide 37

Set the C251 Compiler Options for the Project

To set the C251 compiler options, select the C251 Compiler… command from the Options menu and µVision displays the C251 Compiler Options dialog box. The only options you need to set for the BLINKY example are Include debug information and Source Mode for Code generation. These controls are shown in the following figure.

Make sure to include debugging information in the object file.

Set Code Generation for Source Mode.

NOTE

In any of the option dialog boxes, you may click the Default button to set the controls to the default settings.

38 Chapter 4. Programming

Set the L251 Linker Options for the Project

To set the L251 linker options, select the L251 Linker… command from the Options menu. µVision displays the L251 Linker Options dialog box shown below.

Enter the following text in the Reserve text boxes on the Misc tab shown above.

0xFF0003-0xFF0005, 0xFF003B-0xFF003D, 0xFF007B-0xFF007D

This creates the reserve directive that tells the linker that memory areas 0xFF0003-0xFF0005, 0xFF003B-0xFF003D and 0xFF007B-0xFF007D should not be used for program code. This reserves the space for the interrupt vectors.

MCB251 Evaluation Board User’s Guide 39

Set the Path Specifications for the 251 Tools

You may wish to specify the path to the 251 tools directly in µVision. You may do this in the Environment Pathspecs dialog box. Open this dialog box using the Environment Pathspecs… command in the Options menu.

You may specify the path to BIN directory, the INC directory, and the LIB directory. Additionally, you may specify a temporary directory for the compiler and linker to use when compiling and linking.

40 Chapter 4. Programming

Set the Make Options for the Project

Finally, the make options control how µVision processes the files in your project. Open the Make Options dialog box by selecting the Make… command in the Options menu.

Make sure you select the Run L251 Linker radio button. This links your source files after compiling them.

MCB251 Evaluation Board User’s Guide 41

Build the Project

Now, you are ready to build the project. Select the Make: Build Project

command from the Project menu to begin compiling and linking. µVision responds by compiling the BLINKY.C source file and linking it with the appropriate library files.

This is called making the project. While the make is running, µVision displays the status as shown below.

If errors occur during the make process, a message window appears. If there were warnings or errors in your source file, you may interactively select the error and see the corresponding line in your source file.

When make completes successfully, you are ready to begin debugging the BLINKY program.

42 Chapter 4. Programming

Using dScope to Debug the BLINKY Program

To load the BLINKY in the MCB251 evaluation board using dScope, you need to perform the following steps:

n Load the MON251.DLL CPU driver. n Configure the CPU driver for the appropriate COM port and baud rate. n Configure the CPU driver for serial break. n Load the BLINKY program. n Step through the BLINKY program.

Each of these steps is described in detail below.

Start dScope by selecting the dScope Debugger… command from the Run menu.

This loads dScope and sets the current path to the path in which your project file is saved.

MCB251 Evaluation Board User’s Guide 43

When dScope starts, a screen similar to the following displays.

Module Window

Command Window

To load the MON251.DLL CPU driver, type the following in the command window.

load mon251.dll

This is shown in the following figure.

44 Chapter 4. Programming

Typically, the first time you load the CPU driver for the 251 monitor, you must set the COM port and baud rate. If dScope cannot determine the COM port and the baud rate automatically, the following dialog box appears informing you that dScope could not find the target system.

When using the MCB251 evaluation board, the baud rate should be set for 57,600 baud. You must determine which COM port you use.

Next, you should configure the CPU driver to enable serial breaks. To do this, select the Configuration command from the Peripherals menu. dScope displays the Configuration dialog box shown below.

Set Enable serial break to let dScope stop programs running on the MCB251.

Finally, you are ready to load the BLINKY program. To do so, type the following in the command window.

load blinky /* this loads the blinky program */

g,main /* this steps over the startup code */

/* and stops on the first line of main */

Once BLINKY is loaded, the module window displays the BLINKY program as shown in the following figure.

MCB251 Evaluation Board User’s Guide 45

You may now single step through the BLINKY program by clicking on the StepOver button on the right side of the module window. As you step through the program, you should see the LEDs on the MCB251 changing.

You may display the status of the I/O ports in dScope. Select the I/O-Ports command from the Peripherals menu and dScope displays the dialog box shown on the right.

As you step through the BLINKY program, you will see how the Parallel Ports dialog box mirrors the LEDs on the MCB251 evaluation board.

When you are ready to exit dScope, click on the Stop button in the module window and select the Exit command in the File menu.

NOTE

You must stop the program execution of your target program before you can exit dScope.

46 Chapter 4. Programming

External UART Example

The following example program shows you how to use the external UART to send and receive serial data. The _getkey and putchar routines are included for use with the stream functions like printf.

#include <reg251s.h> #include <stdio.h>

#define DELAY 50000L

#define EXTSIO_ADDR 0xFFE700UL

#define EXTSIO_RBR ((volatile unsigned char far *) (EXTSIO_ADDR)) #define EXTSIO_THR ((volatile unsigned char far *) (EXTSIO_ADDR)) #define EXTSIO_IER ((volatile unsigned char far *) (EXTSIO_ADDR + 1)) #define EXTSIO_IIR ((volatile unsigned char far *) (EXTSIO_ADDR + 2)) #define EXTSIO_LCR ((volatile unsigned char far *) (EXTSIO_ADDR + 3)) #define EXTSIO_MCR ((volatile unsigned char far *) (EXTSIO_ADDR + 4)) #define EXTSIO_LSR ((volatile unsigned char far *) (EXTSIO_ADDR + 5)) #define EXTSIO_MSR ((volatile unsigned char far *) (EXTSIO_ADDR + 6)) #define EXTSIO_SCR ((volatile unsigned char far *) (EXTSIO_ADDR + 7)) #define EXTSIO_DLL ((volatile unsigned char far *) (EXTSIO_ADDR + 0)) #define EXTSIO_DLM ((volatile unsigned char far *) (EXTSIO_ADDR + 1))

#define EXTSIO_CLK 1843200UL

/*----------------------------------------------This function sets the baudrate for the external UART on the MCB251.

-----------------------------------------------*/ void extsio_baudrate ( unsigned long baudrate) { unsigned long baud_divisor; unsigned char lcr_save;

lcr_save = *EXTSIO_LCR; /* Save LCR */ *EXTSIO_LCR = 0x80; /* Set DLAB */

baud_divisor = (EXTSIO_CLK / 16UL) / baudrate;

*EXTSIO_DLL = (unsigned char) (baud_divisor & 0xFF); *EXTSIO_DLM = (unsigned char) ((baud_divisor >> 8) & 0xFF);

*EXTSIO_LCR = lcr_save; /* Restore LCR */ }

MCB251 Evaluation Board User’s Guide 47

/*----------------------------------------------This function performs a general initialization of the external UART on the MCB251.

-----------------------------------------------*/ void extsio_setup ( unsigned long baudrate) { unsigned char dummy;

extsio_baudrate (baudrate);

*EXTSIO_LCR = 0x03; /* 8-bit, 1 stop, no parity */

*EXTSIO_IER = 0x00; /* disable all interrupts */

*EXTSIO_MCR = 0x00;

dummy = *EXTSIO_LSR; dummy = *EXTSIO_MSR; dummy = *EXTSIO_RBR; }

/*----------------------------------------------Send a character out the external UART.

-----------------------------------------------*/ void extsio_putchar ( unsigned char c) { while ((*EXTSIO_LSR & 0x20) == 0);

*EXTSIO_THR = c; }

/*----------------------------------------------Receive a character from the external UART. If no characters have been received, -1 is returned.

-----------------------------------------------*/ int extsio_getchar (void) { if (*EXTSIO_LSR & 0x01) return ((unsigned) *EXTSIO_RBR);

return (-1); }

/*----------------------------------------------_getkey replacement for external UART.

-----------------------------------------------*/ char _getkey (void) { int c;

while ((c = extsio_getchar ()) == -1);

return (c); }

48 Chapter 4. Programming

/*----------------------------------------------putchar replacement for external UART.

-----------------------------------------------*/ char putchar (char c) { extsio_putchar (c); return (c); }

/*----------------------------------------------Wait dummy function

-----------------------------------------------*/ void wait (void) { ; /* just to waits some time */ }

/*----------------------------------------------Setup the external UART for 57600 baud, write the string "Hello World nnn", and repeat.

-----------------------------------------------*/ void main (void) { unsigned int counter = 0;

extsio_setup (57600);

for (counter = 0; ; counter++) { unsigned long i;

printf ("Hello World %u\r\n", (unsigned) counter % 100); for (i = 0; i < DELAY; i++) wait (); } }

/*-----------------------------------------------

-----------------------------------------------*/

Use the following command line to compile the external UART example program:

C251 EXTSIO.C DEBUG MODSRC

Since this example program uses the external UART, you must generate a HEX file and program an EPROM. Use the following command line to link:

L251 EXTSIO.OBJ

and the following command line to generate an Intel HEX file:

OH251 EXTSIO

You may then use the EXTSIO.HEX file to program an EPROM.

MCB251 Evaluation Board User’s Guide 49

Chapter 5. Using the 251 Monitor

The MCB251 comes ready-programmed with the Keil 251 monitor (MON251). The monitor programmed in the Monitor EPROM is setup to communicate at 57,600 baud using the EXT_RS232 interface and 19,200 baud using the INT_RS232 interface with a 12MHz oscillator.

You may use the MON251 DOS terminal program (MON251.EXE) or the dScope for Windows debugger/simulator to quickly download and test your programs.

MON251 Terminal Program

The MON251 terminal program communicates with the 251 monitor using one

of your PC’s serial ports. MON251 lets you:

n Display the contents of the 251’s memory areas in ASCII and hexadecimal, n Interactively change memory contents, n Display and change register contents, n Initialize memory with constant values, n Disassemble the code area, n Assemble in-line code, n Run programs with breakpoints in real-time, n Create up to 50 program breakpoints, n Single-step through your program, n Step over subroutines, n Upload and download Intel HEX files and OMF-251 object files, n Display an online command help menu.

50 Chapter 5. Using the 251 Monitor

Starting the MON251 Terminal Program

Use the following command line to start the MON251 terminal program.

MON251 COM1|COM2|COM3|COM4 INT14|NOINT BAUDRATE(n)

where:

COM1: - COM4: Specifies the serial port to use. You may use the COM port

number (1, 2, 3, or 4) as an abbreviation. COM1 is used by default.

INT14 Specifies that the serial interface is accessed through the

BIOS software interrupt 14H. Direct hardware interrupts are not used. You may use

NOINT Specifies that the serial interface is polled rather than

interrupt-driven. Hardware interrupts are not used. You may use

N as an abbreviation for NOINT.

I as an abbreviation for INT14.

BAUDRATE(

) Specifies the baud rate to use. If this option is omitted,

MON251 defaults to 9600 baud. The value

specifies the baud rate. Valid baud rates are: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, and 57600. You may use an abbreviation for

BAUDRATE.

BR as

The command-line parameters of the MON251 terminal program may be set using the environment variable MON251. You may set this environment variable using the DOS SET command. For example:

SET MON251=COM1 BAUDRATE(1200)

If no parameters are included on the command line, MON251 uses the MON251 environment variable settings. If the environment variable settings are used, the MON251 terminal program displays the following message:

ENVIRONMENT STRING: MON251=<parameters>

MCB251 Evaluation Board User’s Guide 51

Terminal Commands

The MON251 terminal program supports the following commands:

n Exit Exit MON251 and return to DOS. n F1 Exit MON251 and return to DOS. n F2 Transmit the contents of a file. n F3 Echo the contents of the screen to a file. n Help Display the help menu. n ; Comment lines.

Exit: Exit MON251 and Return to DOS

This command closes all files and returns to DOS. For example:

#EXIT

F1: Exit MON251 and Return to DOS

When you enter

EXIT MON251 (y or [n])

F1 or Alt+1, MON251 responds with the following prompt.

Enter Y to exit MON251, close all files, and return to DOS.

F2: Transmit the Contents of a File

When you enter

Input File:

F2 or Alt+2, MON251 responds with the following prompt.

Here, you may enter a file from which MON251 inputs and interprets commands. For example:

Input File: MYINIT.CMD <cr>

directs MON251 to read the contents of the file MYINIT.CMD and interpret them as commands. You may press

Ctrl+C to stop retrieving commands from the

file.

52 Chapter 5. Using the 251 Monitor

F3: Echo the Contents of the Screen to a File

When you enter

Output File:

F3 or Alt+3, MON251 responds with the following prompt.

Here, you may enter a file where the contents of the screen will be copied. For example:

Output File: DEBUG.PRN

directs MON251 to write the screen contents to DEBUG.PRN. Press F3 or

Alt+3 to stop writing screen changes.

If you enter the name of a file that already exists, MON251 responds with the following prompt.

Overwrite existing file (y or [n])?

Enter Y to overwrite the file.

HELP: Display the Help Menu

When you enter the help command, MON251 displays a brief description of all 251 monitor commands.

;: Comment Lines

Any line starting with a semicolon is a comment. Comments may be entered after a command. For example,

#D C:0x4000 ; Show code at 0xFF4000

MON251 ignores any text after the semicolon. Comments are useful when you

F2 to transmit the contents of a command file.

use

MCB251 Evaluation Board User’s Guide 53

Index

_getkey...............................................46

151 CPU...............................................6

20V8...................................................15

251 CPU.............................................14

251 Monitor .......................................49

51/151 DIP Switch...............................7

8051 CPU........................................6,14

A17 DIP Switch...................................7

BAUDRATE......................................50

BR......................................................50

Buffers................................................15

Circuit Description.............................13

COM1 ................................................50

COM2 ................................................50

COM3 ................................................50

COM4 ................................................50

Configuration.....................................14

Configuration Jumpers.........................9

Configuring the MCB251SB ............... 5

Contents of MCB251SB Kit ................ 1

CPU Selection.................................... 10

Example Program

External UART ............................46

FLASH.........................................31

ext_Uart DIP Switch............................6

External UART Example

Program...........................................46

FLASH Example Program.................31

Hardware............................................13

Hardware Requirements.......................3

I/O Device..........................................15

INT1 Jumper ........................................9

INT14.................................................50

Intel 151 .............................................14

Intel 251SB ........................................14

Introduction..........................................1

Kit Contents .........................................1

Dallas 320 .......................................6,14

Dallas 520 ............................................6

Decode Logic.....................................15

DIP Switch

Default Settings.............................. 5

SW1................................................5

DIP Switches........................................ 6

Document conventions........................iv

LED DIP Switch ..................................8

MAP1 DIP Switch ...............................8

MAX232 ............................................16

Memory Device..................................15

MON251

Comment Lines ............................52

Exit Command..............................51

F1 Command................................51

F2 Command................................51

F3 Command................................52

54 Index

Help Command.............................52

Terminal Commands ....................51

MON251 environment variable..........50

MON251 Terminal Program ..............49

Monitor Data Space............................28

Monitor DIP Switch .............................7

Monitor EPROM Addresses...............26

Monitor Interrupt Vectors ..................28

Monitor Memory Map........................27

Monitor Modes...................................11

Monitor Program................................49

Monitor Status Display.......................11

NMI Jumper .........................................9

NOINT ...............................................50

PAGE / NONP Jumper.........................9

PAGE DIP Switch................................7

PAL ....................................................15

PAL Equations ...................................23

Power Supply Circuitry......................14

Printed Board Assembly.....................22

printf...................................................46

Programming......................................27

Prototyping Area ................................17

Push Buttons.......................................16

putchar................................................46

Schematics..........................................18

Serial Port...........................................16

Setup.....................................................3

Software Requirements ........................3

SRC/D2 DIP Switch.............................6

Status LEDs........................................16

Technical Data....................................23

Temic 251A1......................................14

Temic 251G1.................................14,16

UART.................................................16

Uart_INT DIP Switch...........................6

Using µVision ....................................32

Using dScope......................................42

Writing Programs for the 251

Monitor............................................30

Keil MCB251 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual