Table of Contents
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CONTENTS
11.4
SERIAL COMMUNICATIONS UNIT INTERRUPTS .................................................. 11-21
11.5
SERIAL PORT EXAMPLES....................................................................................... 11-21
11.5.1
Asynchronous Mode Example ..............................................................................11-21
11.5.2
Mode 0 Example ...................................................................................................11-23
11.5.3
Master/Slave Example ..........................................................................................11-24
CHAPTER 12
WATCHDOG TIMER UNIT
12.1
FUNCTIONAL OVERVIEW.......................................................................................... 12-1
12.2
USING THE WATCHDOG TIMER AS A SYSTEM WATCHDOG ............................... 12-1
12.2.1
Reloading the Watchdog Timer Down Counter .......................................................12-3
12.2.2
Watchdog Timer Reload Value ...............................................................................12-4
12.2.3
Initialization .............................................................................................................12-5
12.3
USING THE WATCHDOG TIMER AS A GENERAL-PURPOSE TIMER .................... 12-6
12.4
DISABLING THE WATCHDOG TIMER ....................................................................... 12-6
12.5
WATCHDOG TIMER REGISTERS.............................................................................. 12-8
12.6
INITIALIZATION EXAMPLE....................................................................................... 12-12
CHAPTER 13
INPUT/OUTPUT PORTS
13.1
FUNCTIONAL OVERVIEW.......................................................................................... 13-1
13.1.1
Bidirectional Port .....................................................................................................13-1
13.1.2
Output Port ..............................................................................................................13-3
13.1.3
Open-Drain Bidirectional Port .................................................................................13-3
13.1.4
Port Pin Organization ..............................................................................................13-3
13.1.4.1
Port 1 Organization .......................................................................................13-6
13.1.4.2
Port 2 Organization .......................................................................................13-6
13.1.4.3
Port 3 Organization .......................................................................................13-7
13.2
PROGRAMMING THE I/O PORT UNIT....................................................................... 13-7
13.2.1
Port Control Register ..............................................................................................13-7
13.2.2
Port Direction Register ............................................................................................13-8
13.2.3
Port Data Latch Register .........................................................................................13-9
13.2.4
Port Pin State Register .........................................................................................13-10
13.2.5
Initializing the I/O Ports .........................................................................................13-11
13.3
PROGRAMMING EXAMPLE ..................................................................................... 13-12
CHAPTER 14
MATH COPROCESSING
14.1
OVERVIEW OF MATH COPROCESSING .................................................................. 14-1
14.2
AVAILABILITY OF MATH COPROCESSING.............................................................. 14-1
14.3
THE 80C187 MATH COPROCESSOR........................................................................ 14-2
14.3.1
80C187 Instruction Set ...........................................................................................14-2
14.3.1.1
Data Transfer Instructions .............................................................................14-3
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