Microprocessor Engineering

1
Microprocessor Engineering

• Alan Goude

2
Microprocessor Engineering

• Microprocessor Systems
• Microcontrollers
• ARM7 core Processor Family
• specifically NXP LPC2368 microcontroller
• C Programming will be used throughout
• ARM Realview MDK - 'C' compiler other tools
• u-Vision Integrated Development Environment

3
Microprocessor system

• CPU
• Memory ROM and RAM
• Input various
• Output - various

4
Bus system

• Devices connect to microprocessor via bus system
  (often called the memory bus)
• A devices connected to bus must be tri-state
  devices
• only one device is activated at a time
• Consists of 3 bus types
• Address bus
• Data bus
• Control bus

5
Bus operations

• Read
• Write
• Each read/write operation is made up of a number
  of clock cycles or T states
• Each machine instruction is made up of one or
  more read and/or write operations
• This is why we shouldn't compare microprocessors
  simply based on clock speed

6
Address Bus

• unidirectional generated by microprocessor
• number of address lines determines number of
  address locations
• addressable locations 2n where n is the number
  of address lines
• Memory map shows the position of devices within
  the whole of the addressable area

7
Data Bus

• Bi-directional
• Usually matches the word length of the
  microprocessor
• Usually a multiple of 8
• We talk of 8-bit, 16-bit , 32-bit and 64-bit
  processors which refers to the normal word length
  of the microprocessor

8
Control bus

• Consists of potentially many signals. Typically-
• Read
• Write
• Could be single signal - Read/notWrite line
• Interrupt control
• Bus control signals for DMA (Direct Memory
  Access)

9
Microprocessr

• CPU Central Processing Unit
• ALU Arithmetic Control Unit
• Registers
• Control Unit ( usually microcoded)

10
Microprocessor Registers

• General purpose register file
• Status or Flag Register indicate result of last
  instruction executed
• Program Counter (PC)
• Stack pointer
• Special registers Internal to CPU and generally
  not available to the programmer.
• On reset and power up PC is loaded with a
  particular value, typically zero.

11
The Fetch Execute cycle

• Fetch
• memory read cycle
• place in instruction register and decode
• Execute
• may involve additional read and/or write cycles
• Often the whole Fetch-Execute cycle is carried
  out through a pipeline operation involving
  several stages.
• 5 stages are often used (IF, ID, RR, EX, WB)
• The Pentium 4 has 20 stages
• The ARM 7 has 3 stages

12
Microcontroller

• A microcontroller is the integration of
• microprocessor
• memory
• ROM types commonly flash PROM
• RAM Static ram
• peripherals
• parallel input and output(digital I/O)
• Timers and Counters
• Serial input and output (UART, USART, SPI etc.)
• Analogue to digital converters
• PWM, CAPCOM registers, DACs etc.etc.

13
What is an Embedded Computer System

• Special purpose computer usually with one
  specific task or application.
• Usually embedded in a device which often has
  other electronic and mechanical parts
• Usually optimised for the specific task
• Has the usual basic computer components CPU,
  memory, inputs outputs

14
Examples

• consumer appliances
• tv's, mp3 players, dvd's, washing machines etc.
• automotive applications
• engine management, anti-lock braking
• computer peripherals
• hard disk controllers, routers, switches
• medical equipment
• scanners, blood analysers
• telecoms
• mobile phones
• aerospace
• satellite control systems, avionics

15
Some Characteristics

• Very simple to very complex applications
• Often single application
• but concurrent operation
• Could be real-time (hard and soft)
• Program is normally stored in ROM called
  firmware flash ROM commonly
• Could be critical applications
• Interfacing with other devices via peripherals
• Require a range of development tools hardware
  and software
• May use operating system (RTOS)

16
Constraints

• Physical size
• Weight
• Power usage
• Performance throughput and/or response time
• Cost

17
Resulting in -

• limited space
• limited processing power
• 8-bit processor
• limited memory RAM ROM
• only Ks of memory not Ms
• schemes to limit power consumption
• low power modes
• sleep
• standby
• determinism needed for RT guarantee

18
Linksys Wired Wireless Router
19
Linksys WRT54GL Router Access point

• CPU Broadcom BCM4712KPB _at_ 200 MHz
• RAM 16MiBytes (2 x S42S16400 RAM Chips)
• ROM 4MiBytes (Intel TE28F320 C3 Flash ROM)
• I/O
• WAN port One 10/100 RJ-45 port
• LAN port Four 10/100 RJ-45 ports
• Wi-Fi Channels 13
• LED Indicators power, DMZ, WLAN, port 1/2/3/4,
  Internet

20
Microprocessor vs Microcontroller vs Soc vs FPGA

• uP
• General purpose
• external memory and peripherals
• connected by a memory bus
• uC
• uP integrated with memory and peripheral
  interfaces
• families of uC all with same uP but varying
  amounts and types of memory and interfaces.

21
Microprocessor vs Microcontroller vs SoC vs FPGA

• SoC System on a chip
• FPGA Field Programmable Gate Array

Microcontroller-based System-on-a-Chip