Io IoT Device ce Ar Arch chitect ecture e and Pr Programming - PowerPoint PPT Presentation

Io IoT Device ce Ar Arch chitect ecture e and Pr Programming 01219335 Data Acquisition and Integration Chaiporn J Chaipo n Jaik aikae aeo De Department of f Computer Engineering Kasetsart Unive versity Revised 2020-08-20

Ou Outline • Components of typical IoT devices • Hardware platforms • Programming methods 2

Ma Main Co Components Microcontroller Memory (RAM/Flash) Communication Sensors/ CPU Module Actuators Power Supply 3

Mi Microcontroller r Examples • Espressif’s ESP32 ◦ Dual Xtensa cores @240 MHz ◦ 520 KB SRAM ◦ Wi-Fi: IEEE 802.11 b/g/n https://www.electrodragon.com/product/ esp32-wifi-bluetooth-ic-model/ ◦ Bluetooth v4.2 • Microchip’s ATSAMD21G18 ◦ ARM Cortex M0+ @48 MHz ◦ 256 KB programmable flash ◦ 32 KB SRAM http://www.jarzebski.pl/arduino/arduino-i- klony/arduino-m0-zero-pro-atsamd21g18.html 4

Co Communication Device • Medium options ◦Electromagnetic, RF ◦Electromagnetic, optical ◦Ultrasound radio wave Radio bit stream Transceiver 5

Tr Transceiver Characteristics • Service to upper layers: packet, byte, bit • Data rate • Power control • Communication range • etc . 6

Tr Transceiver States • Transceivers can be put into different operational states , typically: ◦ Transmit (Tx) Tx Idle Rx ◦ Receive (Rx) ◦ Idle – ready to receive, but not doing so Sleep ◦ Sleep – significant parts of the transceiver are switched off 7

Se Sensor ors • Main categories ◦ Passive, omnidirectional ◦ Examples: light, thermometer, microphones, hygrometer, … ◦ Passive, narrow-beam ◦ Example: Camera ◦ Active sensors ◦ Example: Radar, ultrasonic sensor • Important parameter: Area of coverage ◦ Which region is adequately covered by a given sensor? 8

Ener Energy S Supply upply • Goal: provide as much energy as possible at smallest cost/volume/weight/recharge time/longevity ◦ Depending on the application, recharging may or may not be an option • Options ◦ Primary batteries – not rechargeable ◦ Secondary batteries – rechargeable, only makes sense in combination with some form of energy harvesting 9

Ener Energy S Supply upply - Re Requirements • Low self-discharge • Capacity under load • Efficient recharging at low current • Voltage stability (to avoid DC-DC conversion) 10

Ba Battery y Examples • Energy per volume (Joule/cc): Primary b batteries Chemistry Zinc-air Lithium Alkaline Energy (J/cm 3 ) 3780 2880 1200 Secondary b batteries Chemistry Lithium NiMH NiCd Energy (J/cm 3 ) 1080 860 650 http://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Lithium-ion_battery http://clipart-library.com/ 11

Ex Example: ample: B Batter ery Lif Life (1) e (1) • Consider a device with average power consumption of 20 mA • If the device is powered by a 3000 mAh battery, how long will the device last without charging? 12

Mu Multiple P Power Con r Consump mption on Mod Modes • Do not run device at full operation all the time ◦ If nothing to do, switch to power safe mode • Typical modes ◦ Controller: active, idle, sleep ◦ Radio mode: Turn on/off transmitter/receiver, both ◦ Strongly depends on hardware • Questions: ◦ When to throttle down? ◦ How to wake up again? 13

Ex Example: ample: B Batter ery Lif Life (2) e (2) • Consider a device whose components’ power consumption characteristics are as follow: Component Power consumption Time fraction in each mode Processor Active mode: 10 mA 10% Sleep mode: 0.01 mA 90% Radio module Transmitting mode: 100 mA 1% Receiving mode: 20 mA 5% Idle mode: 10 mA 94% Sensor Active mode: 30 mA 5% Idle mode: 0 mA 95% • What is the average power consumption of the device? 14

Io IoT M Modul dule B e Boards ds • Designed for easy prototyping • Combining processor, power supply circuit, commonly- used peripherals into a single board http://www.jarzebski.pl/arduino/arduino-i-klony/arduino-m0-zero-pro- atsamd21g18.html https://www.adafruit.com/product/2772 https://www.electrodragon.com/product/esp32-wifi-bluetooth-ic-model/ https://github.com/LilyGO/TTGO-T8-ESP32 15

Ar Arduino Modules • Various communication "shields" LoRa Shield WiFi Shield https://www.arduino.cc/en/Main/Boards http://www.dragino.com/products/nb-iot/item/130-nb-iot-shield.html https://store.arduino.cc/usa/arduino-wifi-shield NBIoT Shield http://www.dragino.com/products/lora/item/102-lora-shield.html 16

BBC' BBC's s Mi Micro:bit https://microbit.org/guide/features/ 17

Ra Raspberry y Pi • By Raspberry Pi Foundation • Controller ◦ 1.4 GHz 64/32-bit quad-core ARM Cortex-A53 • Communication Raspberry Pi 3 Model B+ ◦ Ethernet, WiFi, and Bluetooth Raspberry Pi Zero W https://www.raspberrypi.org/products/ 18

ES ESP32-ba based M sed Modul dules es • NodeMCU-32S https://www.shenzhen2u.com/NodeMCU-32S ◦ LED and switches ◦ USB connector • TTGO T-Beam ◦ LoRa + OLED + GPS modules ◦ Battery charger and holder ◦ USB connector https://www.aliexpress.com/i/32967228739.html • WEMOS D32 Pro ◦ Micro SD slot ◦ Battery charger ◦ USB connector https://wiki.wemos.cc/products:d32:d32_pro 19

KidBri Ki dBright Mo Modul dule ESP32 Module Temperature Sensor Light Sensor - 2 cores @240 MHz - 520 MB RAM USB-C Connector - 4 MB Flash Push Switches Triple-Axis Accelerometer & Magnetometer 16x8 LED Matrix Real-Time Clock Battery External peripheral connectors 20

De Device P Programming

Ty Typical Development Process • Firmware flashing with an external chip programmer Source ce code (C (C/Assembly) Microcontroller Cross Compiler/Assembler Fi Firmware code 010101 U U Uploader 011101 (b (binary) S S 110110 Software B B Chip Programmer 22

Ty Typical Development Process • Firmware flashing with on-chip bootstrap loader Source ce code Microcontroller (C/Assembly) (C module Cross Compiler/Assembler flash memory Firmware co Fi code 010101 U U Uploader Bootstrap 011101 (b (binary) S firmware S 110110 Software Loader (BSL) B B code 23

Ty Typical Development Process • Script uploading with MicroPython firmware Microcontroller 010101 Micr croPython 011101 module 110110 fi firmware (binary) (b uploaded only once flash memory Bootstrap U U Uploader Loader (BSL) S S Python Py Software B B source ce code .py (. (.py py) 24

Ba Basi sic Peri ripheral Co Control wi with Mi MicroPython

Ex Example: ample: LED LED C Contro rol • Let's write code to control the red LED (usually used for indicating WiFi connectivity) 26

LED LED C Control l – Sc Schematic ic • Red LED is connected to IO2 KidBright's Schematic provided by INEX 27

LED LED C Control l – Py Python Code from machine import Pin from time import sleep # make pin 2 an OUTPUT, refer to it as 'led_wifi' led_wifi = Pin(2, Pin.OUT) while True: # set pin 2’s voltage to 3.3V led_wifi.value(1) sleep(0.5) # set pin 2’s voltage to 0V led_wifi.value(0) sleep(0.5) 28

Ex Example: ample: Sw Switch Status • Let's write code to read status of a push-button 29

Sw Switch Status – Sc Schematic ic • Two push-buttons are connected to IO14 and IO16 pins • When a button is pushed, its status reading is 0 • When a button is released, its status reading is 1 KidBright's Schematic provided by INEX 30

Sw Switch Status – Py Python Code from machine import Pin from time import sleep # make pin 16 an INPUT pin with pull-up activated # (i.e., give logic 1 when the pin is floating); # then refer to it as 's1' s1 = Pin(16, Pin.IN, Pin.PULL_UP) while True: # read and print out the button value print("S1 status =", s1.value()) # delay a little to slow down screen output sleep(0.1) 31

Co Conclusi sion • An IoT device usually consists of a processor, power supply, communication module, and sensors • There are various IoT hardware modules in the market • ESP32-based modules are quite popular for beginners • MicroPython allows controlling ESP32-based module with Python scripts 32