Electronic for Software Developers

IoT Con 2015 
Elektronik für
Softwareentwickler
Lars Gregori, hybris labs
02.09.2015

https://labs.hybris.com
development

development
software hardware

development
software hardware
write
compile
run
debug

development
software hardware
write assemble
compile wire
run run
debug “debug"

development
software hardware
write assemble
compile wire
run run
debug “debug"
test

agenda
• basics
• digital
• analog
• more …

basics

basics ~programming
language

Ohm's law
V 
I = — 
R 
V 
R = — 
I 
V = I * R

resistor
V 
I = — 
R
• 10V and 1 kOhm 
• 10V and 10 Ohm

resistor
V 
I = — 
R
• 10V and 10 Ohm
10mA
1mA
1A

resistor
V 
I = — 
R
• 10V and 10 Ohm
10mA
1mA
1A W = V * I = 10W
V2 
W = — 
R

LED
• light emitting diode
• data sheet

LED
• light emitting diode
• data sheet
~API, documentation

LED example
• 5V
• LED data sheet
• 25mA
• 3.3V
• R?
R

LED example
• 5V
• LED data sheet
• 25mA
• 3.3V
• R? Kirchhof’s circuit law
R

LED example
• 5V
• LED data sheet
• 25mA
• 3.3V
• R?
• VR = 5V - 3.3V = 1.7V
• R = 1.7V / 25mA = 68 Ohm
Kirchhof’s circuit law
R

hello world
• Arduino
• arduino.cc
• data sheet
• output: max. 20mA

hello world
• Arduino
• arduino.cc
• data sheet
• output: max. 20mA
~framework

hello world
• buy Arduino, LED, and R
• wire things up
• download IDE and install
• install driver (Windows)

hello world
• wire things up
• Examples / 01.Basics / Blink

hello world

hello world
• wire things up
• upload
• conﬁgure board …

hello world
• wire things up
• upload
• conﬁgure board …
blink faster
Knight Rider

not blinking?
• all wires correct?
• LED polarity? kaputt?
• R too big?

not blinking?
• R too big?
test it

not blinking?
• R too big?
• wrong pin?
• pin kaputt?
test it

not blinking?
• R too big?
• wrong pin?
• pin kaputt?
test it
voltage?

not blinking?
• R too big?
• wrong pin?
• pin kaputt?
• Arduino kaputt?
• upload without errors?
test it
voltage?

not blinking?
• R too big?
• wrong pin?
• pin kaputt?
• Arduino kaputt?
• upload without errors?
test it
voltage?
software?

IO matrix
analog digital
input
output ?

motor
• motor ampere?
• multimeter
• 400mA

motor
• motor ampere?
• multimeter
• 400mA
~debugger

motor
• motor ampere?
• multimeter
• 400mA
• OK for Arduino?
~debugger

motor
• motor ampere?
• multimeter
• 400mA
• OK for Arduino?
~debugger
no

transistor
• ampliﬁer
• electronic switch
NPN

transistor example
note: connect all GND together

IO matrix
analog digital
input
output ✔

digital input

TTL logical levels
• VOH – Minimum OUTPUT
Voltage level a TTL device will
provide for a HIGH signal.
• VIH – Minimum INPUT Voltage
level to be considered a HIGH.
• VOL – Maximum OUTPUT
Voltage level a device will
provide for a LOW signal.
• VIL – Maximum INPUT Voltage
level to still be considered a
LOW.
https://learn.sparkfun.com/tutorials/logic-levels
TTL = Transistor-Transistor Logic

TTL logical levels
• VOH – Minimum OUTPUT
Voltage level a TTL device will
provide for a HIGH signal.
• VIH – Minimum INPUT Voltage
level to be considered a HIGH.
• VOL – Maximum OUTPUT
Voltage level a device will
provide for a LOW signal.
• VIL – Maximum INPUT Voltage
level to still be considered a
LOW.
https://learn.sparkfun.com/tutorials/logic-levels
TTL = Transistor-Transistor Logic
3.3V 
2.4VOH 
2.0VIH 
0.8VIL 
0.5VOL

button
• bounce
~debugger
multimeter
LED
~debugger
oscilloscope
Arduino

button
• bounce
de-bounce
delay(20);

pull-up resistor
• Arduino tri-state logic
• HIGH
• LOW
• high impedance
INPUT_PULLUP

other digital inputs
• reed relais
• hall sensor
• switch
• …
magnetic

IO matrix
analog digital
input ✔
output ✔

analog input

analog input
~debugger:
multimeter
oscilloscope

analog input devices
• microphone
• temperature resistor
• photo resistor

ADC
• ADC - analog-digital converter
• Arduino
• 6-channel 10-bit ADC
• values 210 = 0 - 1023

photo resistor example
https://blog.adafruit.com/2009/05/21/photocells-aka-cds-cells-photoresistors-ldr-light-dependent-resistor/

Schmitt trigger
if (light < 600) 
turnLedOn(); 
else 
turnLedOff();

Schmitt trigger
if (light < 600) 
turnLedOn(); 
else 
turnLedOff();
 
 
 
ﬂicker

Schmitt trigger
if (light < 600) 
turnLedOn(); 
else 
turnLedOff();
if (light < 600 && led == OFF) 
turnLedOn(); 
if (light > 620 && led == ON) 
turnLedOff();
ﬂicker

IO matrix
analog digital
input ✔ ✔
output ✔

analog output

analog output
~debugger:
multimeter
oscilloscope

analog output
• Arduino
• PWM
• Pulse-width modulation

PWM
• LED dimming / fading
• servo motor
• 0 - 180 degree

DAC
• digital-analog converter
• self made:
• low-pass ﬁlter
DAC ICs

IO matrix
analog digital
input ✔ ✔
output ✔ ✔

IC - integrated
circuit

IC - integrated
circuit ~library

IC - integrated circuit
• temperature
• memory
• NFC reader
• distance sensor
• protocols
• I2
C / TWI
• SPI
• UART (serial)

IC - integrated circuit
• temperature
• memory
• NFC reader
• distance sensor
• protocols
• I2
C / TWI
• SPI
• UART (serial)
~debugger 
oscilloscope 
bus pirate 
logic analyzer

Firmata

Firmata
• serial communication
• from PC to Arduino
• Arduino slave
• PC host
• Java, nodejs, Go
• GoBot

hybris labs
prototypes

https://labs.hybris.com/prototype/

Thank you
 
Lars Gregori
@choas

links
• http://ﬁrmata.org/
• https://rabee2050.wordpress.com/2015/06/01/web-
server-control-arduino-ﬁrmata/

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