workshop slide.pdf
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This document provides information about a workshop on mruby and embedded systems being held from September 11-15, 2023. The workshop will cover topics including mruby programming for small devices, controlling circuits with a microcontroller board, and using sensors like a brightness sensor. Attendees will learn to program an LED to blink and change brightness using mruby code, and will interface a CdS brightness sensor with a microcontroller to control an LED based on light levels. The workshop aims to give experience in embedded software development and interacting with electronic components like LEDs through programming.
workshop slide.pdf
- 1. Workshop Kyushu Institute of Technology Kazuaki Tanaka 2023/9/11-2023/9/15
- 2. About Me • Kazuaki TANAKA（たなか かずあき） • Kyushu Institute of Technology, JAPAN Associate Professor • Ph. D in Information Science • Research topics: embedded systems, IoT, mruby, wireless communication
- 3. Research topic: mruby and mruby/c • Ruby language for small devices • OO Programming Language • Target: one-chip microcontroller PIC, ESP32, STM32, etc. • Small memory footprint minimum 20KB • Open-Source Software https://github.com/mruby/mruby https://github.com/mrubyc/mrubyc
- 4. What is Ruby language? • Object Oriented Programming Language – Scripting language – Web application, Ruby on Rails • Matsumoto has said that Ruby is designed for programmer productivity and fun. led1 = GPIO.new(0) while true do led1.write 1 sleep 0.5 led1.write 0 sleep 0.5 end Ruby code example:
- 5. Research topic: wireless communication • LPWA(Low Power Wide Area) communication network
- 6. LPWA • Long range wireless communication – ~10km by small wireless module – Using 920MHz band 24mm 17mm Low power Tx: 43mA Rx: 20mA Sleep: 1.7μA Speed: 1kbps
- 7. Introduction
- 8. This workshop • Experience in embedded software development. • mruby programming • Controlling electronic circuits • Brightness sensor
- 10. Electrical circuit • Micro controller board • Electrical parts and circuit – LED, sensors – Breadboard (prototyping board)
- 11. Run the first program • Coding • Compile and Download Download= transfer compiled program into microcontroller board • Execute
- 12. Programming environment • Open following URL or https://mrubyc-ide.ddns.net/editor/rboard https://bit.ly/45InC1H
- 13. Blinking LED • program1 • First, run this program led1 = GPIO.new(0) while true do led1.write 1 sleep 0.5 led1.write 0 sleep 0.5 end
- 14. Microcontroller board • RBoard • Features – Execute program – Store data – I/O of Pins – Input= Measure voltage – Output= Set voltage HIGH(1) or LOW(0) Pin
- 15. Onboard LEDs • 4 LEDs, each LED is connected to Pin – LED 1: Pin 0 – LED 2: Pin 1 – LED 3: Pin 5 – LED 4: Pin 6 • Set pin voltage to HIGH, then turn on LED Set to LOW, then turn off LED
- 16. Program • GPIO： General Purpose Input and Output led1 = GPIO.new(0) while true do led1.write 1 sleep 0.5 led1.write 0 sleep 0.5 end Pin0 is assigned to variable led1 Iteration write: set voltage sleep: stop execution
- 17. Exercises • Blink two LEDs alternately • Blink four LEDs LED 1: Pin 0 LED 2: Pin 1 LED 3: Pin 5 LED 4: Pin 6
- 18. LED • Light Emitting Diode Current flows from Anode to Cathode Longer: Anode Anode Cathode
- 19. LED Circuit • Make LED on – Current flowing through the LED • Rboard feature – Set voltage of Pin – Set HIGH or LOW
- 20. Wrong circuit Board Pin (HIGH) Pin (LOW) LED The resistance of LED is almost 0. Many current flows, cause damages to LED
- 21. LED circuit Board Pin (HIGH) Pin (LOW) LED Resistor 1K ohm Resistor limits current flowing.
- 22. LED circuit Board Pin (HIGH/LOW) GND LED Resistor 1K ohm GND is always LOW LED on if Pin is HIGH LED off if Pin is LOW
- 23. Breadboard (Prototyping board) • Red holes are connected
- 24. Using breadboard • Connecting a LED and a resistor LED Resistor Longer leg Shorter leg
- 26. Connecting • Use jumper wires Pin 15 GND LED Resistor Pin １５ GND
- 27. Implement your code led1 = GPIO.new(15) led1.setmode(0) while true do led1.write 1 sleep 0.5 led1.write 0 sleep 0.5 end Set pin mode 0: Output voltage 1: Input voltage Pin 15
- 28. Exercises • Blink several LEDs on breadboard You can use Pin15, Pin16, Pin17, Pin18, Pin19, Pin20
- 29. PWM
- 30. PWM Analog output • Output of microcontrollers: Digital – HIGH or LOW voltage – In LED, ON or OFF • We want: Analog – Change voltage – In LED, ON…bright…dark…OFF
- 31. Pseudo analog output • PWM, pulse width modulation • Control HIGH and LOW rapidly – 1000 times a second 0.1 msec. 50% HIGH 50% LOW
- 32. Change brightness • Change brightness => Change duty ratio Time 1 msec. Duty=1 Duty=2 Duty=1023 Duty=1022 Duty=1 Duty=0 Duty=0
- 33. PWM example led1 = PWM.new(15) led1.frequency 10000 while true do for i in 0..1023 do led1.duty i sleep 0.001 end for i in 0..1023 do led1.duty 1023-i sleep 0.001 end end duty: 0 to 1023 0: 0% HIGH 1023: 100% HIGH
- 35. CdS • CdS: Resistance changes with varying light levels. • Microcontroller can detect VOLTAGE
- 36. CdS circuit CdS 3.3V Pin20 GND Resistor 1K ohm R ohm Bright: small R Dark: large R 𝑃𝑖𝑛20 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 = 3.3 × 1𝐾 1𝐾 + 𝑅
- 38. ADC • ADC: Analog Digital Converter – Read voltage at Pin20 – Voltage v 0 < v < 1.5 adc = ADC.new(20) v = adc.read
- 39. CdS example led1 = GPIO.new(0) adc = ADC.new(20) while true do v = adc.read if v<0.5 then led1.write 1 else led1.write 0 end sleep 0.1 end Read voltage from Pin20 Voltage: 0 < v < 1.5 Pin20 for ADC
- 40. Exercises • Brightness sensor • LED changes by brightness – Green: bright – Yellow: a little dark – Red: dark • adc.read returns around 0.2 in dark, and returns around 0.9 in bright
- 41. Conclusion
- 42. Embedded systems • Software and Hardware integration • Software controls hardware – Requires both software and hardware knowledge