geoinformatics iii geo sensor web

Technische Universität MünchenLehrstuhl für Geoinformatik

Geoinformatics III – Geo Sensor Web

Introduction to IoT: Microcontrollers, Sensors, Actuators

Prof. Dr. Thomas H. Kolbe

Chair of Geoinformatics

Technische Universität München

[email protected]

27th of April 2020

Realtime Sensor Observation Service


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27. 4. 2020 T. H. Kolbe: GI3 – Introduction to IoT: Microcontrollers, Sensors, Actuators 2


‘Internet Of Things‘ is when

your toaster mines bitcoins

to pay off its gambling debts

to the fridge

Source: Internet / Twitter

Image: Lidl


IoT – Application Fields


Figure: Patel & Patel 2016: Internet of Things-IOT: Definition, Characteristics, Architecture, Enabling Technologies, Application & Future

Challenges. Int. Journal of Engineering Science and Computing, May 2016


Accessing Sensors / Actuators over the Internet

…comprises the following steps or tiers:

1. Make sensors and actuators controllable by computers

● attach sensors & actuators to a microcontroller / microcomputer

2. Bring sensor data into the Internet / Make actuators

controllable over the Internet

● connect microcontrollers directly / indirectly to the Internet

3. Integration, storage, and analysis of sensor data collected

over distributed sensors / stations

● collect sensor data on software platforms; distribute sensor events

4. Access IoT devices (sensors, actuators) and their

acquired data from application programs over the Internet

● user applications retrieve and send data over the platform(s)



Accessing Sensors / Actuators over the Internet

…comprises the following steps or tiers:

1. Make sensors and actuators controllable by computers

● attach sensors & actuators to a microcontroller / microcomputer

2. Bring sensor data into the Internet / Make actuators

controllable over the Internet

● connect microcontrollers directly / indirectly to the Internet

3. Integration, storage, and analysis of sensor data collected

over distributed sensors / stations

● collect sensor data on software platforms; distribute sensor events

4. Access IoT devices (sensors, actuators) and their

acquired data from application programs over the Internet

● user applications retrieve and send data over the platform(s)


Today and

next week!


Structure of this Lecture

I. Microcontroller & Microcomputer

● Introduction & Overview

● Microcontroller Boards & Extension Boards

● Microcomputer & Extension Boards

II. Sensors

● Definition & Characteristics

● Examples for Sensors & Sensor Boards

III. Actuators & Indicators

● Definition

● Examples for Actuators & Indicator Boards; Dashboards

IV. Developing Microcontroller Systems

● Arduino Integrated Development Environment (IDE)

● Using the Hardware & Input/Output Pins of Arduino-type Microcontrollers

● Important Rules when connecting components



Requirements on Sensor Stations / Nodes

► Sensors need to be configured, controlled, and queried

● many modern sensors employ digital communication protocols

● sensor data readings often need additional calculations / treatments

(like temperature compensation or unit conversions) in order to

determine proper observation values

► Sensor data should be

● registered / stored locally at the station,

● displayed locally at the station, and/or

● transmitted to a remote server requires data encoding,

encryption, and the implementation of communication protocols

► Actuators need to be configured and controlled, too

► Thus, we need a controlling device

● typically realized by a microcontroller or a microcomputer



Microcontrollers (MC, MCU, 𝛍C)

► A microcontroller is an integrated circuit combining

● a microprocessor / central processing unit (CPU),

● working memory (RAM), program storage memory (ROM),

● peripheral functions like communication interfaces, and

● programmable external digital and analog input/output (I/O) lines

in a single package or an encapsulated module

► MCs are typ. programmed to implement a dedicated task

and are embedded into devices to control their functions

● for that purpose they are small, low cost, low power



Microcontrollers

► Important characteristics of Microcontrollers are

● Number of CPU cores

● Type of CPU instruction set (CISC vs. RISC)

● Clock frequency (typ. 8 MHz, 16 MHz, 48 MHz, or 240 MHz)

● Operating voltage (typ. 1.8V, 3.3V, or 5V)

● Power consumption and power saving modes

● Data bus width (typ. 8 bit, 16 bit, 32 bit, or 64 bit)

● Amount of working memory (RAM, typ. 2 KB up to 8 MB)

● Amount of program memory (Flash ROM, typ. 32 KB up to 8 MB)

● Amount of configuration memory (EEPROM, 0 Bytes up to 8 KB)

● Maximum addressable memory (address bus width)

● Type of memory architecture (von Neumann vs. Harvard)

● Number of General Purpose Input / Output (GPIO) lines

● Supported communication interfaces and protocols



Recapitulation: Bits and Bytes

► Bit

● smallest unit of digital data representation

● can be 0 or 1 (i.e. it can distinguish 2 possible values)

● 0 / 1 are typically represented by voltage levels (low / high)

► Byte

● one Byte consists of 8 Bits

● allows to represent 28 = 256 different combinations of 1’s and 0’s

● Byte has been the unit to represent alphanumeric characters, i.e.

single digits (0-9), letters (a-z, A-Z, äöüß), punctuation (;:,.-_/) etc.

● max. 256 different characters / symbols

● today, often 2 Bytes are being used to represent one character to

also cover international alphabets (216 = 65536 characters)

● multiple bytes: 1 Kilobyte (KB) = 1024 Bytes

1 Megabyte (MB) = 1024 KB = 1048576 Bytes



Examples for widely used Microcontrollers


Characteristics \ MC ATmega328 SAMD21 Cortex M0+ ESP32

Manufacturer Atmel / Microchip Atmel / Microchip Espressif Systems

Number of CPU cores 1 1 2

Data bus width 8 32 32

Max. clock frequency 20 MHz 48 MHz 240 MHz

RAM 2 KB 32 KB 520 KB

Flash ROM 32 KB 256 KB 4MB – 16MB

EEPROM 1 KB - (can be emulated) - (can be emulated)

GPIO lines 23 38 34

Hardware interfaces I2C, UART, SPI I2C, I2S, UART, SPI,

USB

I2C, I2S, SPI, CAN,

UART, Ethernet,

BT4.2, WIFI, SDCard

Analog inputs/outputs 6 (10Bits) / 6 (PWM) 14 (12Bits) / 1 (10Bits) 18 (12Bits) / 2 (8Bits)

Used e.g. on these

MC boards

Arduino Uno / Mini /

Nano

Seeeduino LoRaWAN,

Adafruit Feather M0

ESP32-WROVER,

PyCom LoPy4

Market price 1.00 € / unit 2.50 € / unit 2.00 € / unit


Microcontroller Boards

► MCs are typically installed on a printed circuit board (PCB)

together with other functional components like

● input/output interfaces (to connect sensors, actuators, and displays)

● communication interfaces (wired and wireless)

● power supply (very often voltage regulators; sometimes voltage

converters, battery chargers)

● onboard sensors, actuators, and displays



Microcontroller Boards & Peripherals


Sensor1(e.g. GPS, Gas)

Sensorm

Actuator1(e.g. Relay, Servo)

Actuatorn

Indicator1(e.g. display, LED)

Indicatork

Microcontroller Board (e.g. Arduino) or

Microcomputer (e.g. Raspberry Pi)

External Module1

Power Supply

(typ. 3.3V, 5V or 6-15V)

Add-on Boards

(“Shields“ / “Wings“)

Functional

Component1

Functional

Componenti

External Modulej

Ha

rdw

are

Inte

rface

s (e

.g. G

PIO

, I2C

, SP

I, Se

rial, U

SB

)

Ha

rdw

are

Inte

rface

s (e

.g. G

PIO

, I2C

, SP

I, Se

rial)

Hardware Interfaces

Flash ROMRealtime

Debugger

Programming

Interface

RAM EEPROM

CPU(s)

GSM, 3G, 4G

Onboard

Sensors

Battery

Charger

Memory

Card

Onboard

Displays

RTC

Bluetooth

LoRa(WAN)

WiFi

Ethernet

optional functional components:

communication

interfaces

⋮

⋮

⋮ ⋮

⋮



► Functional elements of microcontroller boards:

● microcontroller (CPU(s) + I/O interfaces + clock generator; often

built-in working memory (RAM), program memory (Flash ROM),

configuration memory (EEPROM))

● (additional) working memory (RAM – Random Access Memory)

● (additional) program memory (Flash ROM – Reprogrammable

Read Only Memory)

● (additional) configuration memory (EEPROM – Electrically

Erasable Programmable Read Only Memory)

● (additional) input/output (I/O) interfaces

● programming interface

● optionally: communication interfaces, real time clock (RTC)

● power supply, optionally: battery charger

● optionally: sensors, actuators, indicators



Microcontroller Example: Arduino UNO R3


Image: Make Magazine, CC BY-SA 4.0

USB Connector

External

Power

Supply

(EPS)

Reset Button ► CPU: ATMega328

8 Bit, 16 MHz

● 32 KB Flash ROM

● 2 KB RAM

● 1 KB EEPROM

► Power: 5V over USB

or 7-20V over EPS

► I/O Voltage: 5V

► Programming: over

USBSerial interface

or ISP interface

► Hardware interfaces

● I2C: 1

● SPI: 1

● Serial: 1

● Analog inputs: 6

● Analog outs/PWM: 6

● Digital in-/outputs: 14

► User LEDs: 1

In-System

Program-

ming Conn.

(ISP)

Microcontroller

I/O & Power Connectors


https://de.wikipedia.org/wiki/Datei:Arduino_uno_r3_isometr.jpg


Arduino UNO R3 – Compatible Boards

► compatible boards are typically less expensive (starting from 2.50 €)

► same dimensions, connectors, and CPU (often in a different package)

► often different types of USB connectors and USBSerial interface chips

► some have extra connectors, buttons, LEDs

► some can switch to 3.3V operating and I/O voltage


Seeeduino Lotus V1.1Seeeduino V4.2 no name

Image: Seeed Studio Image sourceImage: Seeed Studio

https://de.aliexpress.com/item/UNO-R3-developent-board-MEGA328P-CH340-CH340G-For-Arduino-UNO-R3-Without-USB-Cable/32665372585.html


Microcontroller Example: Seeeduino LoRaWAN


USB Connector

LiPo

Battery

Conn.

Reset Button

► CPU: ATSAMD21G18

(ARM Cortex-M0+)

32 Bit, 48 MHz

● 256 KB Flash ROM

● 32 KB RAM


or 3.7V LiPo battery

► I/O Voltage: 3.3V


USBSerial interface

or ISP interface


● Gen. Purpose I/O: 20

● I2C: 1

● SPI: 1

● Serial: 2


● Analog outputs: 1

► User LEDs: 1

In-System

Program-

ming Conn.

(ISP)

Microcontroller

I/O & Power

Connectors


LoRaWAN Module

GPS ReceiverImage: Seeed Studio

GPS Antenna

Grove

Module

Conn.

LoRa

Antenna


Microcontroller: Adafruit Feather M0 RFM95 LoRa


USB

Connector

LiPo Battery Connector

Reset Button


(ARM Cortex-M0+)

32 Bit, 48 MHz


● 32 KB RAM





USB interface



● I2C: 1

● SPI: 1

● Serial: 2



● PWM outputs: 8

► User LEDs: 1

LoRa Module

(868 MHz)

Microcontroller

I/O & Power

Connectors


Image: Adafruit

LoRa

Antenna

Conn.


Microcontroller: SODAQ ONE-EU-RN2483-V3


USB Connector

Reset Button


(ARM Cortex-M0+)

32 Bit, 48 MHz


● 32 KB RAM





USB interface



● I2C: 1

● SPI: 1

● Serial: 2



● PWM outputs: 8

► User LEDs: 1 RGB

Solar

Panel

Conn.

Microcontroller


I/O & Power

Connectors

LiPo

Battery

Conn.

GPS ReceiverGPS Antenna

Connector

LoRaWAN

Module

(868 MHz)

LoRa Antenna

Connector

Image: SODAQ

Accelerometer +

Magnetometer


Microcontroller Example: PyCom LoPy4


LoRa & SIGFOX

Modules

WiFi &

Bluetooth

Chip

Antenna

Reset Button ► CPU: ESP32 Dual

Core, 32 Bit, 240 MHz

● 8 MB Flash ROM

● 520 KB + 4 MB RAM

● Real Time Clock

► Power: 3.5 – 5.5V



Serial interface



● I2C: 2

● I2S: 1

● SPI: 1

● Serial / UART: 2



► User LEDs: 1 RGB

LoRa

Antenna

Connector

Microcontroller


I/O &

Power Connectors

Image: PyCom

WiFi &

Bluetooth

Interface


Microcontroller STM32F103C8T6 “Blue Pill”


Image source: Internet

USB

Connector

Reset Button

► CPU: ARM32 Cortex-

M3; 32 Bit, 72 MHz

● 64 KB Flash ROM

● 20 KB RAM

● Real Time Clock


► I/O Voltage: 3.3V,

some 5V tolerant inputs


USB, SWD, or Serial

interface


● I2C: 2; SPI: 2

● Serial / USART: 3

● USB: 1; CAN: 1



● Total I/O pins: 37

► User LEDs: 1

Serial Wire Debug

Connector (SWD)

Microcontroller

I/O & Power

Connectors



Extension Boards for Microcontroller Boards

► For many microcontroller boards a series of hardware

extensions are available

● Extensions are called „Shields“ (Arduino family), „Wings“ (Adafruit

Feather), or „HATs“ (Raspberry Pi) because they are directly

plugged above, below, or next to the microcontroller board

● Shields / Wings / HATs match to a specific (family of) microcontroller

boards (due to pin layout and electrical power & signal compatibility)

► Shields / Wings / HATs typically provide a combination of

● indicators (LEDs, displays like TFT screens, LCDs, buzzers),

● sensors (e.g. GPS, IMU, temperature, humidity, light, gas),

● actuators (e.g. relays, motor drivers, servo drivers),

● interfaces (e.g. WiFi, Bluetooth, LoRa, GSM/3G/4G, SDcard)

● power supply (e.g. battery pack & charger)



Examples for Arduino Shields (1)

► Seeed Solar Charger Shield v2.2

● for operating the microcontroller

board on battery

● support for 3.7V LiPo battery,

5V step-up converter, solar charger

► Seeed Studio Grove Base Shield v2

● provides connectors to attach

Seeed Grove compatible modules

● supports 3.3V and 5V microcontroller

boards


Images source: Seeed Studio

http://wiki.seeedstudio.com/Grove/



► Dragino LoRa/GPS Shield

● GPS receiver with onboard antenna;

external antenna can be connected

● 868 MHz LoRa transceiver chip with

SMA antenna connector

► LCD KeyPad Shield

● adds an LCD display with 2 lines

à 16 characters

● has buttons for e.g. menu navigation

or selection of options


Image: Dragino Image: DFRobot



► Sparkfun MP3 Player Shield

● plays audio files from a Micro SD

card over 3.5mm audio jack

● supports Ogg Vorbis, MP3, AAC,

WMA, MIDI audio formats

► 2.8” TFT touch display

● 320x200 Pixels with 18 Bits color per

Pixel and touch functionalities

● SPI interface; Micro SD card slot to

load and display images


Image: Sparkfun Image: Adafruit


Examples for Adafruit Feather Wings

► Alphanumeric FeatherWing Display

● four digit 14-segment LED display for

text and numbers

● uses I2C connection (3 wires),

software library for easy usage

► Power Relay FeatherWing

● control high current and voltage

devices like pumps, lamps, valves

● can switch up to 5A @ 240V AC

resistive loads or 2.5A inductive loads


Images source: Adafruit


Examples for PyCom LoPy4 Extension Boards

► Expansion Board 3.0

● provides USB connection; connector

and charger for a 3.7V LiPo battery

● Micro SD card slot for storing sensed

data or generally using files

► Pysense

● provides USB connection; connector

and charger for a 3.7V LiPo battery

● temperature, humidity, light sensors,

3 axes accelerometer

● Micro SD card slot


Images source: PyCom


Microcomputer Example: Raspberry Pi 3 B+


Image: ELV.de

USB Connectors

Power

Supply

(USB)

Micro

SD Card Slot

► CPU: Quad Core

ARM Cortex A53,

64 Bit, 1.4 GHz

● up to 64GB Flash ROM

● 1 GB RAM




USBSerial interface

or ISP interface


● USB 2.0: 4

● HDMI; Compos. Video

● Stereo Audio Port

● Ethernet (1 GBit/s)


● I2C: 1; SPI: 2

● Serial: 1

● Analog outs/PWM: 1Ethernet Port

Microcontroller (incl.

Graphics Processor)

I/O & Power

Connectors

HDMI Port

Audio & Composite Video

RAM Chip

Camera Conn.

Display

Connector

WiFi & Bluetooth Chip


Examples for Raspberry Pi HATs

► Grove Pi+

● Grove connectors for 7 digital,

3 analog, 3 I2C, and 1 serial port

● all Grove connectors provide 5V

operating voltage

► Dragino LoRa / GPS HAT

● GPS receiver with onboard antenna;

external antenna can be connected

● 868 MHz LoRa transceiver chip with

SMA antenna connector


Image: Seeed Studio Image: Dragino


Microcontroller Boards vs. Microcomputers


► Examples: Arduino Uno, Adafruit

Feather, ESP8266, ESP32

► typ. single core CPU; 8 Bit, 16 Bit

or 32 Bit data bus width; 8 MHz –

240 MHz clock rate

► no operating system (only a boot

loader to upload a program;

sometimes a system kernel)

► small memory size (2 KB – 4 MB

RAM, 8 KB – 8 MB Flash ROM)

► typ. many I/O lines & interfaces

► low power consumption (modes);

can run on battery power from

days up to years

► very cheap (1 € – 100 €)

Microcomputers

► Examples: Raspberry Pi, Notebook,

Tablet & Desktop PC

► 1…n CPU cores, 32 Bit or 64 Bit data

bus width; 700 MHz – 2 GHz clock

rate

► typically run an operating system like

Linux, Windows, or Android

► larger memory (256 MB – 8 GB RAM)

► user interfaces are built-in: keyboard,

mouse, (touch) display

► require a mass storage device

(SSD, SDcard, hard disk)

► high power consumption; short

runtime on battery power, < 24h)

► more expensive (10 € – 1000 €)








II. Sensors




● Definition








Sensors

► Definition: A sensor is a device that responds to a physical

stimulus (such as heat, light, sound, pressure, magnetism,

or a particular motion) and transmits a resulting impulse

(as for measurement or operating a control).[Mirriam-Webster Dictionary]

► Sensors typically transform one type of energy into

another form of energy

● for example, a temperature or pressure into a voltage level

► Sensor measurements should not affect the measured

quantity (as far as possible)

► Sensors should be insensitive to changes of conditions

that they should not measure



Sensor Characteristics (I)

Important sensor characteristics are

► Sensitivity

● How much does the sensor output changes when the input quantity

being measured changes?

► Precision

● How close are sensor output values when repeatedly measuring the

same measured quantity? (mostly related to noise)

► Accuracy

● How close are sensor output values to the real quantity being

measured? (absolute deviations)

► Insensitivity regarding environmental conditions

● e.g. stability with respect to temperature or operating voltage



Sensor Characteristics (II)

Important sensor characteristics are

► Type of Output

● analog signal (typ. a voltage level)

● digital signal (often using a digital communication protocol)

► Passive or Active

● active: the sensor device sends out a signal to be reflected like a

light or radio impulse (e.g. LASER scanning, RADAR)

● passive: the sensor detects signals emitted from the environment

► Powered or Unpowered

● the sensor device needs / does not need a power supply to work

● all sensors using digital communication need to be powered

● when powered: Power Consumption is also important!



Sensor Characteristics (III)

► Settlement Time

● How fast can the sensor follow changes of the measured quantity

until a correct and stable sensor output value can be achieved?

When sensor values are being digitized (using an analog to

digital converter ADC) or being determined in a digital way,

then these further characteristics are important:

► Resolution

● Onto which number spectrum are the sensor output values being

mapped, i.e. how many different value steps are available?

(e.g.: 10 bits resolution means 1024 values can be distinguished)

► Measuring Rate

● What is the frequency range of measurements (sampling rates) and

how often can the sensor produce a new output value?



Examples for Sensors (1)

► Push Button

● a simple momentary push button

● usage e.g. for menu item selection;

activation / deactivation of some

function; initiation of a process;

on/off switching

● 3.3–5V operating voltage

● digital interface; Grove connector

► 360°Rotary Encoder

● rotation of the axis is transformed to a

pattern of digital pulses

● direction of rotation can be determined

● usage e.g. for volume control, menu

navigation

● a knob can be mounted to the axis




Images: Seeed Studio



► Aosong DHT22 air temperature &

humidity sensor

● temperature range: -40 – 80°C,

resolution: 0.1° accuracy: ±0.5°C

● relative humidity: 5 – 99%,

resolution 0.1% accuracy: ±2%

● measurement period: ≥ 2s

● 3.3–6V operating voltage, 1.5mA max.

● OneWire interface; Grove connector

► Bosch BME280 air temperature,

humidity, and pressure sensor


resolution: 0.01° accuracy: ±1°C



● atmospheric pressure: 300 – 1100 hPa,

resolution: 0.18 Pa accuracy: ±1 hPa

● 3.3–5V operating voltage, 0.4mA max.

● I2C & SPI interface; Grove connector





► Bosch BME680 air quality, humidity,

temperature & pressure sensor

● air quality according to volatile organic

compounds (VOC)


resolution: 0.01° accuracy: ±1°C



● atmospheric pressure: 300 – 1100 hPa,

resolution: 0.18 Pa accuracy: ±0.6 hPa


● I2C & SPI interface; Grove connector

► Loudness Sensor

● detects the loudness of environmental

sound using the onboard microphone

● built-in amplifier and filter;

working frequency: 50 – 2000 Hz

● sensitivity: -48 – 66 dB

● loudness is transformed to an analog

output voltage level


● analog interface; Grove connector





► HM3301 Dust Sensor

● measures the concentration of

particulate matter in the air

● LASER light scattering technology

● direct output of PM1, PM2.5, PM10

mass concentration with unit of μg/m3

● 3.3–5V operating voltage, 75mA max.

● I2C interface; Grove connector

► MH-Z16 Infrared CO2 Sensor

● measuring the range of 0-2000 parts per

million (PPM), accuracy: 200 PPM

● non-dispersive infrared (NDIR)

measuring principle

● warm-up time 3min, response time <90s


● UART interface; Grove connector





► GPS Receiver

● 22 tracking / 66 acquisition channel

GPS receiver

● used for position determination (lat,

lon, height @ WGS84), accuracy: 5m

● cold start 29s, hot start 1s, 1 Hz freq.


● UART interface; Grove connector

► 9DOF Inertial Measurement Unit (IMU)

● 3 axis electronic compass with

0.15 μT/LSB (typ.) sensitivity

● 3 axis gyroscope with programmable

range from ±250 to ±2000 dps

● 3 axis accelerometer with programmable

range of ±2g, ±4g, ±8g, or ±16g

● based the two chips LCM20600, AK09918

● 3.3–5V operating voltage, 5 mA @ 100 Hz






► Soil Moisture Sensor

● can qualitatively test the humidity of

the soil (no quantitative measuring)

● capacitive measuring principle

● corrosion resistant


● analog interface; Grove connector

► M11*1.25 Water Flow Sensor

● consists of a plastic valve body, a water

rotor, and a hall-effect sensor

● flow rate range 0.3 – 6 l/min

● pulse frequency (Hz) = 73Q, Q is flow

rate in l/min


● digital interface (3 pin connector, 0.1in

pin spacing)




Some Remarks on Sensors

► Sensors need to be calibrated

● often they come calibrated from the manufacturer

● sometimes they need to be recalibrated in regular intervals

► For each kind of phenomenon there are sensors available

in different price classes (can go from 0.01 to 5000 €)

● cheap sensors typically low accuracy, low resolution

● can be used to observe trends, but often not suitable to

measure e.g. absolute gas or particulate matter concentrations

● however, there are many use cases in which this is sufficient

► Gas sensors are often not only sensitive to one type of gas

● for example, CO sensors often react to other gases, too

(hence, an increased sensor output value can have different reasons)

► Always download and check the datasheets!








II. Sensors




● Definition








Actuators

► Definition: a mechanical device for moving or controlling

something. [Mirriam-Webster Dictionary]

► Similar to sensors, actuators typically transform one type of

energy into another form of energy

► Typically electrical signals are transformed into mechanical

energy

● rotation, lifting, moving by a motor, servo, valve, solenoid

● movement of air molecules: wind, but also acoustics

► Actuators can also be used to emit electromagnetic waves

● light by a lamp, LED, display

● radio frequency signals like microwaves



Indicators / Displays

► Actuators are often used as indicators by producing a

signal that is visible, audible, or tactile

► Purpose: communicate information about the state of

a system (typically to a human)

► visual indicators are called displays

► Examples are

● screens, LEDs, lamps, flasher

● meters, counters, gauges

● loud speaker, head phone

● siren, buzzer

● vibration and force-feedback devices (e.g. in Smart Phones)

● braille terminal (for the blind)



Examples for Actuators (1) – Indicators

► LED Bar

● 10 segment LED gauge bar controlled

by an MY9221 chip

● 1 red, 1 yellow, 1 light green, and 7

green LEDs

● can be used e.g. as a level indicator



► 4 digit 7-segment LED display

● controlled by a TM1637 chip

● used to display numeric values, time, or

1-4 characters (as far as they are

representable with 7 segments)







► LCD Character Display

● 16 characters×2 lines;

built-in English and Japanese fonts

● switchable LED backlight

● can be used to display text, numbers,

messages, menus etc.



► OLED Display

● available in different sizes (0.96in / 1.12in)

and pixel resolutions (128×64 / 128×128)

● single color / 16 gray scales

● can be used to display text, numbers,

messages, menus, graphics etc.

● 5V / 3.3–5V operating voltage






► TFT Display

● 2.4in full color display, 320x200 pixels

● 16 bits color per pixel; touchscreen

● SPI interface; Micro SD card slot to

load and display images

● 3.3V operating voltage, 100mA max.

● direct connector to an Adafruit Feather

► Relay

● used to switch larger electrical loads

like lamps, pumps, motors

(max. 250V AC or 30V DC, 5A)




Image: Seeed Studio Image: Adafruit


Examples for Actuators (4)

► Servo

● motor + potentiometer to drive (move,

turn, or shift) a mechanism

● angle controlled via PWM signal

● torque: 1.5–1.8 kgf∙cm

● turning speed: 0.12–0.16s / 60°



► Water Pump

● suction lift: 10cm, spit out lift: 50cm

● flow rate: 1.31 ±0.26 l/min

● 5mm vinyl tubing can directly be attached

● 10–13V operating voltage, needs its own

power supply; no load current: 250mA




Dashboards

► Indicators and control elements are also called instruments

► A dashboard is a dedicated composition of instruments with

the function of a user interface to a system

► Purpose

● give overview and important details on the status of a system by

showing information about different sub systems in a comprehensive

and user-friendly way

● control a system by providing elements like switches, buttons,

knobs, joysticks to change the operation parameters of sub systems

► A dashboard has to address the specific information and

control demands of the type of user it is dedicated for

● a captain has to see different status information about a ship than

the chief engineer or machinist



Examples for Dashboards


Image: Aaron Logan, CC BY 1.0

Image: Hans Braxmeier from Pixabay

► Dashboards are also called instrument panels

Image: Yovko Lambrev, CC BY 3.0

https://en.wikipedia.org/wiki/File:Lightmatter_Dashboard.jpg

https://de.wikipedia.org/wiki/Datei:Kozloduy_Nuclear_Power_Plant_-_Control_Room_of_Units_3_and_4.jpg







II. Sensors




● Definition








How to Program Microcontroller (Boards)

► Microcontroller boards typically have no operating system,

but come with a boot loader

● the boot loader receives a user program transferred from the

Integrated Development Environment (IDE) on the development

computer and stores it in the reprogrammable Flash ROM

● also called „uploading“ or „burning“ the program into Flash ROM

● after uploading the program is typ. immediately started


USB Cable


How to Program Microcontroller (Boards)

► For some microcontroller boards specific buttons must be

pressed or some pins need to be connected to enable

upload mode

● refer to the board documentation

● in most cases, when the MC board is connected via USB to the

development computer, switching to upload mode is automatic

► When no bootloader is there or when the bootloader soft-

ware itself should be replaced: ISP programmer required



Uploading Programs to a Microcontroller Board

► While the program development for microcontrollers is

typically carried out on a developer computer using an IDE,

the compiled program (sketch) has to be transferred to the

microcontroller in order to be executed

► Using a bootloader

● most microcontroller boards come with a pre-installed bootloader

software (to be used with the Arduino IDE)

● the program (sketch) is uploaded to the MC board typ. using a Serial

connection (often via USB) and permanently stored in the Flash ROM

● the upload process typ. can be initiated directly from the IDE; the MC

board automatically detects this and switches to “upload mode”

► Using a microcontroller programming device

● if no bootloader is provided in the microcontroller or if the bootloader

itself should be programmed



Arduino Integrated Development Environment IDE

The Open Source development environment for the Arduino

comes with many integrated functions:

► Source code editor

► Compiler

► Uploading tool

► Serial console

► Abstracts from and works with many different

microcontroller boards and CPUs

● Support for specific boards can easily be added

► Manages software libraries

It can be freely downloaded from www.arduino.cc for MacOS,

Linux, and Windows


http://www.arduino.cc/


Programming within the Arduino Framework

► Arduino programs are called Sketches

► Sketches have to be implemented in the programming

languages C and C++

► Sketches consist typically of two parts:

● The method setup():

● setup() is called once when the microcontroller board is switched on,

or when a reset condition has been met (e.g. the user presses the

‚reset‘ button). Afterwards, the loop() method is called.

Typically this method is used to initialize attached hardware

(configuration of GPIO pins, attached sensors etc.).

● The method loop():

● loop() is a method that loops infinitely (until the MC board is switched

off). Everytime the execution reaches the end of the loop() method, it

will be restarted again.

Typically this method performs the regular and repetitive activities

(e.g. reading and displaying data from sensors, transmit data).



The First Arduino Program: Blink an LED

/* Turn on an LED for one second, then off for one second, repeatedly.

Most microcontroller boards have an on-board LED that can

be controlled by a user program. There is a predefined macro

LED_BUILTIN that has the proper digital pin name for the selected

microcontroller board (often this is digital pin 13).

*/

// the setup function runs once when you press reset or power the board

void setup() {

// initialize digital pin LED_BUILTIN as an output.

pinMode(LED_BUILTIN, OUTPUT);

}

// the loop routine runs over and over again forever:

void loop() {

digitalWrite(LED_BUILTIN, HIGH); // turn LED on (HIGH is the voltage level)

delay(1000); // wait for 1000ms = 1 second

digitalWrite(LED_BUILTIN, LOW); // turn LED off by making the voltage LOW

delay(1000); // wait for a second

}



Getting Started with Microcontrollers

1. Collect the relevant hardware

● microcontroller board

● some sensors, actuators, indicators / displays

● connection cable to a developer computer

● possibly a power supply (e.g. battery), if not powered by USB cable

2. Prepare the required software

● download & install the Integrated Development Environment (IDE)

for the developer computer

● possibly download & install a hardware driver for the USB interface

chip of the microcontroller

3. Connect the microcontroller to the developer computer

4. Start the IDE, load a demo application (e.g. “Blink”),

compile and upload the program onto the microcontroller



The 2nd Arduino Program: Print messages

/* Print the text message "Hello World!" to the Serial port. Then every two

seconds further messages ”...and again: Hello World!" are printed.

The serial port is typically connected to a Serial/USB converter and,

hence, the text is sent over USB to the connected developer computer.

Open the Serial Monitor Window in the Arduino IDE to see the messages.

*/

// the setup function runs once when you press reset or power the board

void setup() {

// initialize serial communication at 9600 bits per second:

Serial.begin(9600);

delay(6000); // wait 6 seconds before printing the first message

Serial.println("Hello World!");

}

// the loop routine runs over and over again forever:

void loop() {

delay(2000); // wait two seconds

Serial.println("...and again: Hello World!");

}



The 3rd Arduino Program: Command an LED

/* Command an LED over the Serial connection. Open the Serial Monitor Window

in the Arduino IDE and type in the input line at the top 0 and <Return> to

switch the LED off, and any other number and <Return> to switch it on.

At the bottom of the Serial Monitor choose "New line" and "9600 baud”.

*/

void setup() { // runs only once after power on or reset

Serial.begin(9600); // initialize serial communication at 9600 bps

pinMode(LED_BUILTIN, OUTPUT); // initialize pin LED_BUILTIN as an output

}

void loop() { // the loop routine runs over and over again forever

while (Serial.available() > 0) { // if any characters were received,

int ledstatus = Serial.parseInt(); // try convert them to an integer number

if (Serial.read() == '\n') { // look for the newline: <Return> pressed

if (ledstatus == 0) digitalWrite(LED_BUILTIN, LOW);

else digitalWrite(LED_BUILTIN, HIGH);

}

}

}



Remarks on the Usage of Serial Ports

► the Arduino board has only one hardware UART / serial port

● in Arduino sketches this port is named "Serial"

● the serial port can be used via the USB connector (USB serial) or

by connecting a device to digital pins D0 (RX) and D1 (TX)

► additional Serial ports can be emulated in software

● using the Arduino library SoftwareSerial

● certain digital I/O pins can be employed as TX and RX lines

● users can choose their own names for SoftwareSerial ports

► some microcontrollers (and boards) offer more than one

UART / serial port

● all ports have different names (SerialUSB, Serial1, Serial2, Serial3)

● often their USB port is attached not to "Serial", but to "SerialUSB"

(this is the case, for example, for Seeeduino LoRaWAN)



Overview of Hardware Serial Ports

Board USB CDC Name Serial pins Serial1

pins

Serial2

pins

Serial3

pins

Arduino Uno,

Nano, Mini

Serial 0(RX), 1(TX)

Arduino Mega Serial 0(RX), 1(TX) 19(RX),

18(TX)

17(RX),

16(TX)

15(RX),

14(TX)

Arduino DUE SerialUSB (native

USB Port only)

0(RX), 1(TX) 19(RX),

18(TX)

17(RX),

16(TX)

15(RX),

14(TX)

Arduino

Leonardo

Serial 0(RX), 1(TX)

Seeeduino V4.2 Serial 0(RX), 1(TX)

Seeeduino

LoRaWAN GPS

SerialUSB (native

USB Port only)

connected to

GPS module

can be

configured

to diff. pins

can be

configured

to diff. pins

can be

configured

to diff. pins

Adafruit

Feather M0

RFM95 LoRa

Serial (internally

mapped onto

SerialUSB)

0(RX), 1(TX) can be

configured

to diff. pins

can be

configured

to diff. pins

can be

configured

to diff. pins



Arduino Connectors & Pin Naming

► Arduino connectors have standardized pinouts

► most pins can be used for different I/O purposes


Image: Alberto Piganti (pighixxx), CC BY-SA, see https://www.pinterest.de/pighixxx/

https://www.pinterest.de/pighixxx/


Arduino Digital and Analog Pins

► In the Arduino development environment the digital and

analog pins are addressed using their names/numbers

► Pins 0-13 denote digital inputs/outputs

● use pinMode(pin, mode) to determine I/O direction

(mode: INPUT, INPUT_PULLUP, OUTPUT)

● use digitalWrite(pin, level) to set the output voltage

(level: HIGH ≙ VCC, i.e. 3.3V or 5V; LOW ≙ 0V)

● use digitalRead(pin) to read the logic level (result is HIGH or LOW)

► Pins A0-A5 denote the six analog inputs

● use analogRead(pin) to determine voltage level at pin using the

built-in analog-to-digital converter (ADC), (resolution is 10 bits,

0 ≙ 0V, 1023 ≙ 5V)

● analog pins A0-A5 can also be used as digital inputs/outputs, e.g.

pinmode(A2,OUTPUT); digitalWrite(A2,HIGH);



Remarks on the Usage of I/O Pins

► digital pins 0 and 1 are also used by the Serial port

● do not use for digital I/O, if the Serial port should be used (also

important with regard to program uploads)

► on most MC boards, digital pin 13 is connected to an LED

► pins A0-A5 can also be addressed using pin numbers 14-19

► most pins are also used for specific hardware interfaces

● pins 18, 19 (or A4, A5): I2C interface

● pins 10-13: SPI interface

● pins 3, 5, 6, 9-11: usable as pulse width modulation (PWM) outputs

● when the respective hardware interface is being used, these pins

cannot be used for digital or analog input/output

► non-Arduino Uno boards typically provide further pins and

different hardware interface mappings (check the docs!!)



2nd Exercise: Add a Sensor

1. Choose some sensor and connect it to the microcontroller

● e.g. temperature & humidity sensor DHT22 Grove module

● use proper cabling to connect the sensor module (e.g. Grove cable)

2. Prepare the required software

● start the IDE and download a specific software using the library

manager of the IDE

● for some devices, multiple libraries are available choose one

3. With the installation of a library typ. some demonstration

programs have also been loaded

● choose a demo and check, if some configurations need to be

adapted in the source code (e.g. pin numbers)

● typ. the programs print messages over the Serial interface

4. Compile & upload the demo program, open the console



Practical Rules when connecting components (1)

► Check operating voltages: Ensure that the voltage of the power

supply matches the operating voltage of the microcontroller board

● typical operating voltages are 3.3V or 5V. Do not put 5V to a board that only

accepts 3.3V – or you’ll most likely kill the board.

● often microcontroller boards have voltage regulators reducing the voltage

level from the power connector down to 3.3V or 5V

● hence, if a microcontroller board is powered by the USB connector (which

has 5V), you cannot automatically assume that the board itself runs on 5V;

it can also be less (3.3V)

● this is important when connecting external modules or shields / wings:

ensure that the operating voltage of the module or shield matches the

operating voltage of the microcontroller board

► Checking operating voltages is always important when connecting

modules to a microcontroller board, a shield, or to each other




► Everything needs to be powered: all components typically need to

be connected to a power supply.

● when connecting a shield / wing to a microcontroller board, its power

supply is normally provided through the connector

● when connecting external modules you need to make sure that the

external component either receives power from the microcontroller board

or is powered separately using its own power supply.

● when connecting external modules using the Grove module system from

the company Seeedstudio, the power supply of the modules is typically

provided through the 4-pin Grove connector cable

● if a connected module has its own power supply, you must connect the

Ground (GND) pins of the microcontroller board and the module, but you

must not connect the anode (positive power pin, often labeled as VCC or

+5V or +3.3V) of the microcontroller with the respective anode of the

component




► Provide enough power: all components draw energy from the power

supply. Ensure that the power supply is capable to provide at least as

much power as required by all components together

● not all components and parts draw constantly the same current; often the

demand jumps according to different activities. For example, when a WiFi

transmitter is becoming active it can easily draw up to 200mA

● when the entire circuit is powered just by a small battery with limited

capacity or by the voltage regulator of the microcontroller board, the

operating voltage can drop to a critical level, if too much power is drawn by

the components. This can lead to failure of operation, caused e.g. by

spurious resets of the microcontroller

● for example, if an Arduino is powered over the USB connector from a

connected computer or using a USB charger, the 5V pin of an Arduino can

deliver at maximum 500mA, but the 3.3V pin only 150mA (Arduino Uno) or

50mA (Arduino Nano) respectively

● for higher demands use an external power supply (with own regulator)




► Check pins before connection: when connecting I/O or interface pins

between components, it has to be known which pins are Input or Output pins

● Input pins are used to sense a voltage level (could be a logic level or an

analog voltage), i.e. to receive or read signals / data

● Output pins are set to a specific voltage level (could be a logic level or an

analog voltage), i.e. to emit or write signals / data

● typically the Output pins of one component are connected to Input pins of

the other component and vice versa

● it is also allowed to connect multiple Input pins to a single Output pin

● but: do not connect an Output to another Output unless you really know

what you are doing! Setting one Output to logic 1 level (i.e. 5V or 3.3V

depending on the operating voltage) and the other to logic 0 level (i.e. 0V

or Ground (GND)), will create a short circuit. This can damage the devices




► Check pins before connection: when connecting I/O or interface pins

between components, it has to be known which pins are Input or Output pins

● some I/O pins of microcontroller boards or of external modules have a

fixed configuration. However, many I/O lines of microcontroller (boards)

can be freely configured by the user to operate as Input or Output. These

are called General Purpose I/O (GPIO) pins

● this means that the direction (in / out) of GPIO pins depends on software

and, hence, on the program created by the user. The direction can even be

switched during program execution

● thus, in order to check for pin compatibility when connecting GPIO pins you

need to learn about the pin configuration from checking the user program




► Data protocols: connect pins supporting the same protocol

● when an external module uses a specific protocol, for example I2C, make

sure to connect all required I2C pins of the module with those pins on the

microcontroller board, which are dedicated to I2C

● some microcontroller boards offer multiple instances of the same interface

type (e.g. multiple I2C, Serial, USB, or SPI ports). In this case you can

choose one, but ensure that you configure your software to use this port

● for some hardware connections the lines have to be crossed between

connected components. For example, when using the RS232 serial

communication interface the “transmit” pin (TX) of one component has to be

connected to the “receive” pin (RX) of the other component and vice versa.

The same applies to the so-called handshake pins (if used) - “clear to send”

(CTS) and “ready to send” (RTS), which also must be cross connected


geoinformatics iii geo sensor web

Documents