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Microprocessor-based Systems

Microprocessor-based Systems. Course 5 Special-purpose microprocessors. Special-purpose microprocessors. Architecture dedicated for a well-defined scope Types: Microcontrollers a computer system in a single integrated circuit Designed for control applications (enbedded systems)

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Microprocessor-based Systems

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  1. Microprocessor-based Systems Course 5 Special-purpose microprocessors

  2. Special-purpose microprocessors • Architecture dedicated for a well-defined scope • Types: • Microcontrollers • a computer system in a single integrated circuit • Designed for control applications (enbedded systems) • Digital signal processors (DSP) • Designed for (high speed) signal processing

  3. Digital signal processing DSP • Replace analog signal processing schemes • Why digital processing? • higher noise immunity (significant difference between logical 0 and 1, hard to influence with noise) • higher precision • results does not depend on environment changes (temperature, humidity, pressure) or power supply changes • allows implementation of complex processing procedures (e.g. filters with many poles) • results are repeated in time (no aging of components) • changes in the processing procedure does not impose changes in the hardware (usually changes are made only in the program not in the hardware scheme)

  4. Signal processing procedures • Filters, convolutions, transforms (Fourier, Laplace, Z) + Y(t)=  f()X(t-)d - where: Y(t)- the output function (signal) X(t)- the input function (signal) f(t)- transformation (processing) function In the digital field the integral is changed into a sum: + Y(nT)=  f(kT)*X(nT-kT) k=- where: Y(nT) – the discreet output signal X(nT) – the discreet input signal f(nT) – the discreet transformation function

  5. Architectural characteristics of digital signal processors • Multiply and Accumulate Unit - MAC • Replaces a classical ALU • Multiple data and program buses • 2-4 buses • Internal memory for program and data • RAM, ROM, EPROM memories for data and program • Multiple register sets • More register banks • String oriented addressing modes • Automatic indexing, circular buffers • Complex multiply and accumulate instructions • variations of MAC instructions

  6. MAC – Multiply and Accumulate Unit

  7. Internal scheme of the TMS320C25

  8. Internal scheme of TMS320C25 - RAM – memory blocks: - B0- 256*16 - data and program; - B1- 256*16 – data - B2-32*16 – data - ROM – internal program memory (non-volatile memory) - MAC –multiply and accumulate unit - AR0-7- auxiliary registers - ARP – pointer to auxiliary registers - DP – domain pointer - PC – program counter

  9. TMS320 families and versions • 16 bits processors for integers: TMS320C10, TMS320C20 şi TMS320C50 • 32 bits processors for floating point: TMS320C30 şi TMS320C40 • multi-processor architecture for multimedia processing: TMS320C80

  10. Applications with DSPs • Electric motors and actuators • Intelligent sensors • Measuring devices • Signal analyzers (ex. Digital Oscilloscope) • Medical devices • coder/decoders for audio/video signals • Modems, communication controllers, routers • Musical instruments, • Electronic toys, • Sound synthesizer, • 3D graphical accelerators, • image processing and recognition

  11. Limitations of DSPs • Limited frequencies for on-line processing • the processing time of a signal sample limits the maximum sampling frequency and consequently the maximum frequency of the input signal (half of the sampling frequency) • Discreet input and output values • limited number of discreet values • Discreet processing – not continuous like in the case of analog schemes

  12. Microcontrollers • Definition: a (whole) computer system in a single VLSI integrated circuit • Components: • CPU, • ROM memory (for program), • RAM memory (for data), • interrupt system • input/output ports, • Timers/Counters • Analog to digital converters and digital to analog converters • Other interfaces (PWM, WD)

  13. Destination • Control and monitoring applications • Embedded systems • Intelligent sensors • Advantages: • Low costs • Small dimensions • Reduced power consumption

  14. The structure of the I 80C31/51 uC

  15. Components of the I8031/51 uC • - CPU – Central processing unit • executes the instructions • - ROM – non-volatile program memory • contains the application program and some constant parameters • it may be PROM, EPROM or EEPROM, FLASH ; • dimension: 0 to 32kB; extendable to 64 KB • - RAM –data memory • stores variables and the stack • the first part – 4 sets of 8 registers – the general purpose registers • there is a bit addressable zone – for efficient use in case of logical variables • dimension: 128-512 bytes; extendable with an external memory (not recommended) • the interrupt system – • handles internal and external interrupts/events • interrupt sources: • 2 external lines, serial cannel, counters/timers • clock generator – • synchronize the CPU • generate the source clock signal for other frequencies (e.g. for the serial cannel)

  16. Components of the I8031/51 uC • Input/Output ports – • handles input and output digital signals • 4 or 6 ports of 8 signals; • a signal may be of input, output or bidirectional • Serial channel – • implements the RS 232 protocol – serial asynchronous character-based, bidirectional communication; • optional - I2C –serial bus for external components • Timer 0, 1, 2 – • set of 2 or 3 timer/counters • used for events/impulse counting • for delays • for frequency generation • -DAC – digital to analog converter • generates an analog output signal • it is optional • - CAN – analog to digital converter • reads analog signals (8 in this case) • WD – watch dog • PWM – Pulse Width Modulation

  17. Characteristics of the I8031/51 • CPU • reduced instruction set • instructions executed in a fixed time (ex: 1 us) • ROM memory • 0-32KB – for program • internal and external memory • RAM memory • 128-256 bytes • 4*8 internal registers • Special function registers (SFRs) mapped on the data (RAM) memory space

  18. Interfaces • Serial channel(s): • RS232 - mandatory • I2C - optional • Network interface (ex: CAN) - optional • Input/Output ports • 4-6 ports * 8 bits (inputs, outputs or bidirectional) • Timers/Counters • Counting events (impulses) • Delay generation • Frequency generator • Real-time clock • PWM – pulse width modulation • for the generation of “continuous” signals, using digital ones • cheaper and easier to build • WD – watch dog • for self-control of proper operation • Resets itself in case of an error

  19. Working modes • Normal • All components are working (are supplied) • Idle mode • Only the memory and the clock generator is supplied • low consumption • Power-down mode • Only the memory is supplied (in order to preserve parameters) • the power consumption is almost undetectable

  20. Processor variants

  21. Other μC families • Intel - I8048, • Microchip - PIC 12, PIC16, PIC17 • ARM • Motorola 68C05

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