Hardware FundamentalsHardware Fundamentals

Instructor: G. Rudolph, Summer 2006 2

Key Hardware Components Microprocessor Memory Peripherals (I/O) Bus “Glue Logic”

Instructor: G. Rudolph, Summer 2006 3

JCX Major Hardware Components JStamp controller SRAM Flash JSimmBoard

2 RS232 Serial COM ports 1 JTAG port 1 IrDAport 1 Battery Pack Connector

Instructor: G. Rudolph, Summer 2006 4

JCX Major Hardware Components

Motor Board Control up to 4 motors through 1 port

Sensor Board Connect up to 8 sensors through 2 ports

4X Lego Boards JSimm Backplane (Bus)

Instructor: G. Rudolph, Summer 2006 5

RCX Major Hardware Components H8379 processor 32 KB RAM IR Port Battery Pack Holder Motor Board

Control up to 3 motors Sensor Board

3 sensors LCD Screen 4 Buttons

Instructor: G. Rudolph, Summer 2006 6

Bus? A “Bus” is just a wire

connects components together allows them to communicate

The JCX Backplane is just a bus (30-pin bus)

The Internet is just a bus Serial and printer cables are

“busses”

Instructor: G. Rudolph, Summer 2006 7

Watchdog Timer Usually implemented in hardware The Aj-80 has one, don’t know about

the H8379 If the timer expires, the systems resets Critical for many embedded systems If system goes haywire, reset to known

good state Not part of desktop systems

Instructor: G. Rudolph, Summer 2006 8

Other Hardware PiecesOther Hardware Pieces

Be aware that they are there Be able to answer basic questions

about what they are and their role in the system Wait states Jumper switches DMA channels PALs, FPGAs

Instructor: G. Rudolph, Summer 2006 9

Programming is…An increasingly-high level abstraction

for Driving the correct signals In the correct sequence At the correct time On one or more wires To enable meaningful

communication

Instructor: G. Rudolph, Summer 2006 10

Software is… An increasingly high-level abstraction

of hardware More Flexible Cheaper to reproduce and distribute

once built

Instructor: G. Rudolph, Summer 2006 11

Interrupts Stop the CPU and tell it to do

something else Programming interrupt handlers is

just like any other kind of programming, with restrictions

Fundamental enabler of conditional behavior/execution

Instructor: G. Rudolph, Summer 2006 12

Interrupts Shared data/memory problems

discussed in the text are a common source of problems in multitasking systems

How easy it is to solve them often depends on what software libraries you have to help

Languages such as C and Java differ in how interrupts are handled

Instructor: G. Rudolph, Summer 2006 13

Interrupts At Application LevelAbstract upward to An Event Handler A callback Method

Synchronization and mutual exclusion are “easy” to write in Java

Easy is not always appropriate