Representing Numerical Data Analog Any signal that varies continuously over time Mechanical Pneumatic Hydraulic Electrical Digital Quantities are represented by discrete values Mechanical Pneumatic Magnetic Electrical

Digital vs Analog Digital (Discrete) Analog (Continuous) Sampling Rate Ex: MP3 Encoding

Digital vs Analog Pros of Digital Systems Easier to Design Data Storage is easy Accuracy and Precision easier to maintain Operation can be programmed Less effected by noise Limitation of Digital Systems Real World Representation Processing digitized signals takes time

Dealing with the analog world Reading Analog and Feeding Back Analog Signal comes from some device sensor (pressure valve, flow meter, mic, etc) as analog Use a ADC to convert Process the digital signal Use DAC to convert back to analog Most systems digitize as early as possible and delay conversion back to analog as late as possible

Digital Number Systems Decimal 0-9 Base 10 system 786 – 7 hundreds, 8 tens & 6 units (ones) 7 being the most significant 6 being the least significant Do we use the decimal system in digital systems? Why or Why not?

Digital Number Systems Binary 0-1 Base 2 Can we still represent any quantity that is represented in binary? – 1 fours, 0 twos & 1 units = 5 10 Largest decimal number that can represented with 16 bits

Physically representing binary Switch opened or closed Voltages between a certain range +2 to +5 represent 1 -5 to -2 represent 0 Magnetic Polarity Diode – conducting or nonconducting Pits or No pits on a CD

Timing Diagram Used to show how one or more digital signals changes over time. Used for hardware testing and embedded system debugging Basic Timing for PCMCIA I/O Card Interface on SH7751

Circuits Different circuits will alter the same input(s) in different ways. All circuits follow some type of logic and sometimes referred to as logic circuits

Serial vs Parallel Transmission Serial – bits are sent in sequence “serially” one after another over a signal line Parallel – multiple lines are used to send bits simultaneously Which is faster or better?

Digital Computers CPU – control and arithmetic/logic operations Microprocessor – CPU in a integrated circuit (pins attached to other digital circuits) Microcontroller – all parts of a computer (CPU, memory, I/O ports) all in one IC.