Arbeitskreis Hardware. Prof. Dr. Michael Rohs, Dipl.-Inform. Sven Kratz MHCI Lab, LMU München

Transcription

1 Arbeitskreis Hardware Prof. Dr. Michael Rohs, Dipl.Inform. Sven Kratz MHCI Lab, LMU München

2 Arbeitskreis Hardware 2 Schedule (preliminary) Date Topic (preliminary) 2.5. Introduction to embedded interaction, microcontrollers, hardware & software tools 9.5. keine Veranstaltung (CHI) soldering ISP adapter, AVR architecture LED displays, LED multiplexing, transistors, electronics basics AVR architecture, AVR assembler, sensors: light, force, capacity, acceleration, etc PCB design & fabrication, EAGLE, 3D printing keine Veranstaltung (Pfingsten) I2C: interfacing to other chips (EEPROM, realtime clock, digital sensors) Displays (character LCDs, graphics LCDs), audio (speakers, amplification, opamps) 4.7. Actuation: stepper motors, servo motors Communication: fixedfrequency RF, ZigBee, Bluetooth Project Project

3 Arbeitskreis Hardware 3 ELECTRONICS BASICS

4 Arbeitskreis Hardware 4 Ohm s Law Ohm s Law: U = I R ó I = U / R ó R = U / I [Ω] Power loss: P = U I ó P = I 2 R ó P = U 2 / R [W] Resistor power ratings U I R P (heat) U Also denoted as V

5 Arbeitskreis Hardware 5 Resistors in Series V = V1 V2 R = R1 R2 Voltage divider V 1 = V R 1 / (R 1 R 2 ) V 2 = V R 2 / (R 1 R 2 ) Kirchhoff s Voltage Law! V i = 0 closed loop R 1 V 1 V V I R 2 V 2

6 Arbeitskreis Hardware 6 Resistors in Parallel I = I 1 I 2 ó U / R = U / R 1 U / R 2 ó 1 / R = 1 / R 1 1 / R 2 ó R = R 1 R 2 / (R1 R2) (R: resistance) ó G = G 1 G 2 (G: conductance) Current divider I 1 = I R 2 / (R 1 R 2 ) I 2 = I R 1 / (R 1 R 2 ) Kirchhoff s Current Law! I i = 0 node I V R 1 I 1 R 2 I 2

7 DC Voltage and Current Sources V Ideal V R Real V Battery I Ideal I Real R Michael Rohs, LMU München Source: Paul Scherz: Practial Electronics for Inventors. 2 nd edition, McGrawHill, Arbeitskreis Hardware 7

8 Arbeitskreis Hardware 8 Measuring Voltage and Current Measuring Voltage: Measuring Current: V = 6V R 1 = 10kΩ R 2 = 5kΩ R in = 10 5 Ω V V = 1.5V R 1 = 10kΩ R 2 = 10Ω R in = 0.2Ω V Actual voltage: 4.0V Measured voltage: 3.9V 3% error Actual current: 150mA Measured voltage: 147mA 2% error

9 Arbeitskreis Hardware 9 Charging Capacitors Charge 9V Discharge C U Source: Paul Scherz: Practial Electronics for Inventors. 2 nd edition, McGrawHill, 2007.

10 Arbeitskreis Hardware 10 OPERATION AMPLIFIERS (CONTINUED)

11 Arbeitskreis Hardware 11 Operational Amplifiers Ideal opamps Rule 1: openloop voltage gain: A O = Rule 2: Infinite input impedance: R in = Rule 3: Input terminals draw no current If negative feedback: Rule 4: V V = 0 Ideal opamp: Real opamp: R in = R out = 0 V out = A O (V V ) V out = A O (V V ) Figure author: Inductiveload, public domain

12 Arbeitskreis Hardware 12 Operational Amplifiers Opamp circuit diagram V : noninverting input V : inverting input V out : output V S : positive power supply V S : negative power supply Omegatron, CCBASA Negative feedback Rule 4: V V = 0 Closedloop operation Used to control gain (V out /V in ) Ong saluri, CCBASA

13 Arbeitskreis Hardware 13 OpAmps as Comparators Opamp in openloop setup (no negative feedback) Ideal opamp has openloop voltage gain: A O = Real opamp voltage limited by supply voltage (V S, V S ) " $ V out = # %$ V S V 1 > V 2 V S! V 1 < V 2 Disadvantages Slow: Opamps designed for linear operation with negative feedback Compatibility with digital logic not guaranteed à use dedicated comparator chips

14 Arbeitskreis Hardware 14 AVR ATtiny13 Architecture Analog Comparator Source: Atmel Datasheet

15 Arbeitskreis Hardware 15 ATtiny13 Analog Comparator Compares inputs AIN0 () and AIN1() Sets ACO if AIN0 > AIN1 Can trigger interrupt (on ACO rise, fall, or toggle) Registers control comparator: ADCSRB, ACSR, DIDR0 Source: Atmel Datasheet

16 Arbeitskreis Hardware 16 LIQUID CRYSTAL DISPLAYS

17 Arbeitskreis Hardware 17 LCD Displays Typical: 16x2 characters, background illumination Standardized pin assignment Table Source: Display Elektronik GmbH Datasheet

18 LCD Displays Instruction Set Standardized instruction set (HD44780U display driver) Clear display Return home Entry mode set: cursor move direction, display shift Display on/off: switch cursor and/or display on/off Function set (4 or 8bit interface) Set CGRAM or DDRAM address (CG = char. generator, DD = display data) Read busy flag Read/write RAM Specific initialization procedure to set mode 4 or 8bit interface Michael Rohs, LMU München Arbeitskreis Hardware 18

19 Arbeitskreis Hardware 19 Project Ideas Where to use embedded hardware? Embedded interaction? Displays? Lighting? Sensors? Longterm measurements? Actuation, motors, movement? Communication? 3D printing?

20 Arbeitskreis Hardware 20 Brainwriting Repeat 5 times 3 minutes: On paper, fill one row with 3 ideas Pass on paper clockwise Read other ideas, fill next line with 3 more ideas Select the 3 best ideas 10 minutes Present selected ideas