ARM Microcontroller Interfacing Hardware and Software

Transcription

1 ARM Microcontroller Interfacing Hardware and Software Warwick A. Smith Elektor International Media BV p.o box ZG Susteren The Netherlands

2 Table of Contents Introduction 6 Target Audience 6 Prerequisites 7 Introduction to the ARM Microcontrollers used in this Book 7 AT91SAM7S256 basic features: 7 Hardware Requirements 9 Summary of hardware requirements: 9 Software Requirements 10 Advice on Learning a New Microcontroller 10 Approach Taken in this Book Software and Hardware Setup Installing the YAGARTO GNU ARM Toolchain Installing YAGARTO Tools Installing the GNU ARM Toolchain Installing the Eclipse IDE Hardware Setup Recommended Hardware Using Different ARM Microcontrollers Using Microcontrollers with Different Processor Cores ICE JTAG Emulator for Programming and Debugging Interfacing Suggestions Loading a Program to the Microcontroller Using the DBGU Serial Port Debugging Template Files and Example Programs Template Files and Example Programs Used in this Book Using the Atmel Example Programs Microcontroller Hardware AT91SAM7S Packaging AT91SAM7S Hardware Basic microcontroller circuit References 45 1

3 2. Digital Outputs Interfacing LEDs LED Interfacing Quick Reference LED Interfacing Explanation and Calculations Some Measured LED Voltages Interfacing Transistors Bipolar Junction Transistors (BJT) Transistor Interfacing Quick Reference Transistor Interfacing Explanation and Calculations Field Effect Transistors (FET) MOSFET Interfacing Quick Reference MOSFET Interfacing Explanation and Calculations A Comparison of BJT and FET Transistors Interfacing Optocouplers Power Transistors, Relays, Solenoids and Motors Power Transistors Higher Power BJTs Power MOSFETs Relays and Solenoids Software for Driving Digital Outputs What the Software Must Do Example Software Programs Alternate Program Other Considerations Timers and Interrupts Timers Realtime Timer (RTT) Periodic Interval Timer (PIT) Watchdog Timer (WDT) Timer Counter (TC) Interrupts Interrupts on the ARM7 and AT91SAM7S Nonnested Interrupts using GCC Extension Nested Interrupt Code Single Interrupt Nested Interrupts 107 2

4 Consecutive Nonconsecutive 4. Digital Inputs Interfacing Switches Local Switches Field Switches Software for Setting up and Reading Single Inputs Ill Switch Debounce Software Interfacing Keypads Keypad Software Keypad Software I/O Pin Connections 118 I/O Pin Connections Keypad Software with Switch Debouncing The Concept of Drivers LCD and Seven Segment Displays LCD Character Displays LCD Interfacing Hardware LCD Interfacing Software Seven Segment Displays DC Motors and Stepper Motors DC Motors DC Motor Speed Control Silicon Errata DC Motor Direction Control Stepper Motors Wave Drive Full Step Drive Half Step Drive Microstepping Drive Analogue Signals and PWM Audio ADC ADC Pins and Reference Voltage Basic ADC Interfacing ADC Switch and Keypad Reader Analogue Signal Conditioning PWM Audio 172 3

5 Initialisation, 8. Serial Ports RS RS TWI(PC) USB About USB USB Hardware More on USB USB Device Software Atmel USB Example Programs SD Memory Cards SD Memory Card Basics Introduction and Card Sizes Supply Voltage and Current Memory Capacity Clock Speed Write protection SPI Port SPI Port Operation AT91SAM7S SPI Port and SD Card Interfacing SD Card Sockets SD Memory Card Operation in SPI Mode SD Card Protocol in SPI Mode SD Card Registers Reading and Writing the SD Card SD Card Initialisation Miscellaneous Notes on SD Cards SD Card Software Reading and Writing Hardware Resources Used Initialisation of the SD Card Reading and Interpreting SD Card Registers Raw Writing and Reading Data FAT File System SD Card Software FAT File System Implementation About the FAT File System Software Porting the FAT File System Code 226 4

6 ARM9 10. Advanced ARM Microcontrollers 10.1 AT91SAM7SE 228 ARM AT91SAM7 SE Features AT91SAM7SE Evaluation Kit AT91SAM7SE Programming ATSAM3U ARM CortexM ATSAM3U Features ATSAM3UEK Evaluation Kit ATSAM3U Programming 10.3 AT91SAM AT91SAM9263 Features AT91SAM9263 Evaluation Kit AT91SAM9263 Programming 10.4 ARM Core Comparisons Index 248 5