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: 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 – Serial channel –
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
bytes
4*8 internal registers
Special function registers (SFRs) mapped on the data (RAM) memory space

18. Interfaces Serial channel(s): Input/Output ports Timers/Counters
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 Idle mode Power-down mode
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 256 20 16 16,24 512 ROM/ EPROM RAM Speed MHz
Type
ROM/ EPROM
RAM
Speed MHz
Interfaces
80C31
80C51
87C51
4k ROM
4k EPROM
128 33
-UART (RS 232),
2 counters, 4 ports
80C32
80C52
87C52
8k ROM
8k EPROM
256 20
3 counters, 4 ports
83C550
87C550 16
2 counters, 4 ports,
8 analog channels on 8 bits, watch-dog
80C552
83C552
87C552
16,24
-UART (RS 232), I2C,
3 counters, 6 ports,
8 analog channels on 10 bits, watch-dog, 2 PWM outputs
80C592
83C592
0-16k ROM16k EPROM
512

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