* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slides12-hardware
Survey
Document related concepts
Video camera tube wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Charge-coupled device wikipedia , lookup
Nanogenerator wikipedia , lookup
Cavity magnetron wikipedia , lookup
Power MOSFET wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Surge protector wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Electromigration wikipedia , lookup
Current source wikipedia , lookup
Rectiverter wikipedia , lookup
Opto-isolator wikipedia , lookup
Current mirror wikipedia , lookup
Transcript
Hardware Basics Electricity • Electricity is the flow of electrons • Atoms contain – In the nucleus (center) • Protons with a positive charge + • Neutrons with no charge (no consequence here) – “Orbiting” around the nucleus • Electrons with a negative charge - - ++ + - Charged Atoms • Atoms with more protons that electrons – Positively charged – Try to acquire additional electrons to get back in balance • Atoms with more electrons than protons – Negatively charged – Want to give up electrons to get back in balance • If you set up an imbalance, electrons will try to jump (flow) between atoms to correct this – This flow is electricity Conductors and Insulators • Materials that allow electrons to flow easily are conductors – Most metals are good conductors • Materials that don’t allow electrons to flow easily are insulators – E.g., plastic, rubber, glass • Some materials can be influenced to change from conducting to insulating (a very useful property) Semiconductors Basic Law of Charges • Like charges repel each other • Opposite charges attract each other + + - - • Exert a force – Can do work: e.g., move something + - Charge • Charge is measured in Coulombs ( C ) – (A unit we won’t use much) – Measure of how many more protons than electrons in a substance – 1 Coulomb = 2.15 x 1018 excess protons 2.15 x 1018 extra electrons = -1 C Electromotive Force (Voltage) • Charge has the ability to do work – A “potential” to e.g. move something in one direction or another • Difference in potential (in charge) provides a force: Electromotive Force (EMF): Voltage Extra electron s + EMF (voltage) Flow of electrons • If this is a conductor then ½ the excess electrons will very rapidly flow to the other end to balance the charge Extra electron s Conductor EMF (voltage) + Flow of electrons • If this is a conductor then ½ the excess electrons will very rapidly flow to the other end to balance the charge Conductor ½ the extra electrons 0 voltage Flow of electrons • If this is a conductor then ½ the excess electrons will very rapidly flow to the other end to balance the charge • And then things are not very interesting Conductor ½ the extra electrons 0 voltage Flow of electrons • If this is a conductor then ½ the excess electrons will very rapidly flow to the other end to balance the charge • And then things are not very interesting – Hence we set up circuits (cycles, loops) to keep this going Flow of Electrons • “Current” is the flow of electrons • Measured in Amperes (Amp, or A) – 1A is 1 Coulomb of charge flowing past a point per second Current vs. Voltage • Water analogy – Useful, but only goes so far • Coulombs analogous to quantity (gallons) • Amps analogous to flow rate (gallons / sec) • Voltage analogous to pressure (lbs/ft2) Resistance • Can have a lot of flow at low pressure or a lot of pressure but low volume – Depends on the size of the pipe • Resistance is analogous to the size of the pipe • Resistance is the opposition to current flow • Measured in Ohms ( Ω ) Ohm’s Law • Relates current, voltage, and resistance • Current normally denoted by variable I • Voltage normally denoted by variable V • Resistance normally denoted by variable R V=I*R Ohm’s Law • V = IR •R=V/I •I=V/R V I R Ohm’s Law • In the electronics we will do, we tend to (try to) hold the voltage constant (or zero) – Typically 5v • starting to use 3.3v, but 5v still most common • I=V/R I=5/R – Raise the resistance, current drops – Lower the resistance, current rises Ohm’s Law • I=V/R I=5/R – Raise the resistance, current drops – Lower the resistance, current rises • What happens if we lower the resistance towards zeros? Ohm’s Law • I=V/R I=5/R – Raise the resistance, current drops – Lower the resistance, current rises • What happens if we lower the resistance towards zeros? – Current goes towards infinity – Power = V * I (related to heat) • Boom! (or Poof!) Current Limiting • Important – This is how you (literally) fry hardware if you don’t pay attention (trust me, I know) • Always think carefully (and check!) that the path from 5v source – From power supply, or from output pin of a chip to ground (0v location) has appropriate resistance – Not a “short circuit” ~0Ω – Current limiting resistor at value needed to stay within current limits of the device Aside: Units • Volts, Amps, Ohms • Normally use metric system unit prefixes mega kilo M k milli micro nano pico m μ n p million thousand one thousandth millionth billionth trillionth 1,000,000 1,000 1 0.001 0.000 001 106 103 100 10-3 10-6 10-9 10-12 Examples 5V with 10Ω 5/10 A = 0.5A = 500mA • For typical chips you will use = Poof! 5V with 100Ω 5/100 A = 50mA • Still Poof! 5V with 250Ω 5/250 A = 20mA • OK for PIC processors, not for lots of other digital electronics 5V with 10kΩ 5/10000 A = 0.5mA • Good for most digital electronics Schematic Diagrams xx • • • • • • • • Wire, connection, cross, hop-over Resistor, variable resistor (pot, rheostat) Battery, switch Capacitor, electrolytic capacitor Diode, LED Transistor (PNP, NPN) Inductor, transformer Integrated circuit Schematic Diagrams AC vs. DC • DC – Direct Current – Current flows steadily in one direction – Most of what we will do is DC V • AC – Alternating Current – Current flows in one direction then another – Wall current does this • Alternating 60 times per sec • 60 Hz V Capacitance • Capacitor – Device with two conducting plates separated by insulating material (called dielectric) – Stores electric charge in the dielectric – Water metaphor • Consider a pipe with a rubber balloon blocking it • DC current bulges out the balloon (charges the capacitor) – But then stops flowing – Release the pressure the charge drains back out over time • AC current can go back and forth continuously Capacitor blocks DC but allows AC to pass Capacitance • Capacitance is measured in Farads ( F ) and denoted by variable C – Amount of charge divided by voltage across plates • Charge (in Coulombs) denoted by Q • C=Q/V Series and Parallel Circuits • Series circuit • Parallel circuit Series and Parallel Circuits • Combining resistors R1 R2 • Rtotal-series = R1 + R2 R1 R2 • Rtotal-par = (R1 * R2) / (R1 + R2) Series and Parallel Circuits Combining capacitors C1 C2 • Ctotal-series = (C1 * C2) / (C1 + C2) C1 C2 • Ctotal-par = C1 + C2 Digital Electronics • Computer circuits treat signals as digital values – Consider signals to only have two states: 1 or 0 – +5v is considered to be “1” – 0v is considered to be “0” Digital Electronics • But need to leave some room for error or fluctuation +5v 1 – Between VHMin and +5v considered 1 – Between 0v and VLmax considered 0 VHMin ?? – Between VLmax and VHMin is undefined (and unpredictable) • Can pass through this but you don’t want to stay there long VLmax 0 0v