In this presentation we introduce some of best-known microcontrollers in the context of the IoT MOOC at EdX

1. Electronics
Microcontrollers for IoT Applications
Leopoldo Armesto
Senior Lecturer
Universitat Politècnica de València
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2. Outline
Microcontroller
Signals
Memory
Architecture
Alternatives
Electronics for IoT
ESP Processors
Examples
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3. Microcontroller signals
Digital vs. Analog: A digital signal varies between two possible states HIGH or LOW, while an
signal that can take any value within a range of voltages.
Digital Input: An external device controls the voltage and the microcontroller ‘monitor’ its
changes, so we can read it as HIGH or LOW.
Digital Output: The microcontroller can set a HIGH or LOW voltage.
Analog Input: An internal ADC converts the analog value into a decimal number (typically
discrete values with 10-bit to 16 bit resolution).
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4. Microcontroller signals
PWM (Pulse modulated width): A periodic signal with variable HIGH/LOW times. Typically used
to control transistors, generate frequencies, etc... They can be seen as ‘analog’ signals for
components with slow dynamics, such as motors or analog filters.
Interrupts: Special signals that will interrupt the current program flow so that a higher priority
task can be executed.
External: External signals can generate an interrupt on specific pins.
Timers: Most microcontrollers include timers to measure time or to execute tasks
periodically.
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5. Microcontroller signals
Bus signals: Used to transmit digital data between the microcontroller and another
external device.
UART: Serial communication with two lines (RX and TX) between two devices.
I2C: Serial communication with two lines (SDA and SCK). Master-slave
architecture.
SPI: Serial full-duplex communication with four lines (CLK, MOSI, MISO,SS).
Master-slave architecture.
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6. Microcontroller memory
Programmemory(Flashmemory):
Where we store our code, non-volatile.
Large, compared to data memory, because is cheap.
Datamemory:
RAM (SRAM): Where we store variables that we use in our code. It is deleted on start-up (volatile).
Special Function Registers (SFR) are connected to specific peripherals such as de ADC or Timers.
ROM (EEPROM): Where we store long-term variables. Usually is even shorter than SRAM, because is expensive.
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7. Microcontroller architecture
MCUClock
Program
Memory
Data Memory
GPIO
Bus Peripherals
Timers
Interrupts
ADC
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8. Microcontroller alternatives
Microcontroller
• Simple to use
• Low consumption
Microprocessor
• OS
• Computational
Power
• Compatible with
many external
devices
DSP
• Similar to uC, but
specialized for
signal processing
• Requires
advanced
knowledge.
FPGA
• Very fast
• Need to think as a
circuit designer.
• Deployment is
much slower.
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Arduino Uno WiFi Rev.2 Raspberry Pi 3B+ TI DSP Alhambra board

9. Electronics for IoT
Arduino Uno WiFi
• Easy to use.
• Expensive compared to other alternatives.
ESP8266
• Cheap
• Programmed with Arduino IDE
• WiFi
ESP32
• Cheap
• Programmed with Arduino IDE
• WiFi
• Faster than ESP8266
Raspberry Pi 3 B+
• More expensive than Raspberry Pi Zero W
• Ethernet connection.
• SC Card
• Camera
Raspberry Pi ZeroW
• Quite cheap.
• WiFi & Bluetooth.
• SD Card.
• Camera
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10. ESP8266
ESP-01 :
Very-low cost Wi-Fi module
Can extend Wi-Fi capabilities of Arduino Uno (and similar) through UART connection.
4 GPIO available.
ESP-12E:
17 GPIO available (13 in NodeMCU)
1 analog input (0V~1.6V)
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ESP-01
NodeMCU
ESP-12E
ESP8266MOD

11. Wemos D1 R2
A development board using ESP8266 compatible with Arduino Shields.
Characteristics:
WiFi 802.11
13 GPIO. 1 analog input (3.3V max).
4Mb Flash Memory
80Mhz/160Mhz clock speed
Micro USB (programming and serial communication).
Power jack, 9~24V. 11
Wemos D1 R2

12. ESP32
Wi-Fi & bluetooth (BLE)
32 GPIO available
18 Analog inputs channels (12 bits)
10 Touch inputs
2 DACs
4 SPI, 2 I2C and 3 UART interfaces
SD controller, Ethernet, CAN, IR, Motor PWM, LED PWM
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ESP32-WROOM-32

13. Wemos D1 R32
A development board using ES32 compatible with Arduino Shields.
Characteristics:
WiFi 802.11
Bluetooth: v4.2 BR/EDR BLE
18 GPIO & 6analog input (3.3V max).
4Mb Flash Memory. 520KB RAM
240Mhz clock speed
Micro USB (programming and serial communication).13
Wemos D1 R32

14. Examples
Relay remote control using ESP-01
Requires an external USB-UART interface for programming
Ideal for simple home automation projects
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15. Examples
Weather station:
Measures: Temperature & Humidity DHT11/22, Pressure, Altitude & Temperature BMP180, Light intensity LDR;
Rain value (Rain sensor).
IoT Cloud server for logging data.
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16. Examples
Starter kit for IoT:
Basic I/O: 2 push buttons, 2 LEDs, 1 RGB LED, 1 Potentiometer
Sensors: Humidity & Temperature Sensor (DHT11), Analog Temperature Sensor (LM35), Light sensor (LDR)
IR communications
Buzzer.
OLED Screen: 128x64 pixels
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Wemos D1 R32
Multi-sensor shield
OLED screen 128x64

17. Electronics
Microcontrollers for IoT Applications
Leopoldo Armesto
Senior Lecturer
Universitat Politècnica de València
17