Hardware Fundamentals Key Hardware Components n n n

Hardware Fundamentals

Key Hardware Components n n n Microprocessor Memory Peripherals (I/O) Bus “Glue Logic” Instructor: G. Rudolph, Summer 2006 2

JCX Major Hardware Components n n JStamp controller SRAM Flash JSimm. Board n n 2 1 1 1 RS 232 Serial COM ports JTAG port Ir. DAport Battery Pack Connector Instructor: G. Rudolph, Summer 2006 3

JCX Major Hardware Components n Motor Board n n Sensor Board n n n Control up to 4 motors through 1 port Connect up to 8 sensors through 2 ports 4 X Lego Boards JSimm Backplane (Bus) Instructor: G. Rudolph, Summer 2006 4

RCX Major Hardware Components n n n H 8379 processor 32 KB RAM IR Port Battery Pack Holder Motor Board n n Sensor Board n n n Control up to 3 motors 3 sensors LCD Screen 4 Buttons Instructor: G. Rudolph, Summer 2006 5

Bus? n A “Bus” is just a wire n n n 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 6

Watchdog Timer n n n Usually implemented in hardware The Aj-80 has one, don’t know about the H 8379 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 7

Other Hardware Pieces n n Be aware that they are there Be able to answer basic questions about what they are and their role in the system n n Wait states Jumper switches DMA channels PALs, FPGAs Instructor: G. Rudolph, Summer 2006 8

Programming is… An increasingly-high level abstraction for n Driving the correct signals n In the correct sequence n At the correct time n On one or more wires n To enable meaningful communication Instructor: G. Rudolph, Summer 2006 9

Software is… n n n An increasingly high-level abstraction of hardware More Flexible Cheaper to reproduce and distribute once built Instructor: G. Rudolph, Summer 2006 10

Interrupts n n n 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 11

Interrupts n n n 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 12

Interrupts At Application Level Abstract upward to n An Event Handler n A callback Method n Synchronization and mutual exclusion are “easy” to write in Java n Easy is not always appropriate Instructor: G. Rudolph, Summer 2006 13