The ESP32-WROVER-B MCU

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CPU Pinout

Please note: The pin numbers IOxx on the ESP32 correspond to the GPIO pin numbers

Datasheet: https:// www.espressif.com /sites/default/files/documentation/esp32-wrover-b_datasheet_en.pdf

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Meaning of pins on ESP32

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How to program the processor

	Several development tools are available: ESP_IDF: The official Espressif development tool. Includes a gcc compiler for the ESP8266 and the ESP32 Please see: https://docs.espressif.com/projects/esp-idf/en/latest The Arduino IDE Needs extensions for these processors and the different CPU boards see: https://docs.espressif.com/projects/esp-idf/en/latest MicroPython see: https://micropython-docs-esp32.readthedocs.io/en/esp32_doc

Several development tools are available:

ESP_IDF: The official Espressif development tool.
Includes a gcc compiler for the ESP8266 and the ESP32

Please see:
https://docs.espressif.com/projects/esp-idf/en/latest

The Arduino IDE
Needs extensions for these processors
and the different CPU boards

see:

https://docs.espressif.com/projects/esp-idf/en/latest

MicroPython

see:
https://micropython-docs-esp32.readthedocs.io/en/esp32_doc

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Flashing the code

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esptool

esptool is called from the Makefiles in ESP-IDF
esptool is used when we upload code from the Arduino IDE to the processor flash
esptool is used with Micropython IDE on uPyCraft/Thonny

installs Micropython onto the processor flash

In the above cases the use of esptool is hidden to us.

We can however also execute esptool directly.

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How to write a Micropython program?

First we need a Micropython interpreter!

You find the sources here:

https://github.com/micropython/micropython/

In the repository you find ports for the ESP8266 and the ESP32.

In order to compile the code you need the ESP-IDF and its cross compilers

The code compiles into a binary file (firmware-combined.bin) which contains a boot loader and the interpreter.

This binary must be uploaded and flashed.

For documentation of the ESP32port of Micropython look at

http://docs.micropython.org/en/latest/esp32/tutorial/intro.html

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How to communicate with the Micropython interpreter?

We use a serial connection passing through the micro USB connection.

As soon as we connect the processor card to the PC we see the serial port to connect for communication

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What is REPL?

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The communication tools: minicom

You see the command prompt and you can interact with Micropython.

But \x85 how to upload scripts?

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The command line tool ampy

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IDE for Micropython: uPyCraft

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Thonny

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Thonny

Thonny is a complete Integrate Development Environment (IDE)

which lets you

Access the REPL
Create directories on the Micropython file system
Upload scripts
Syntax check scripts
Run scripts
Install Micropython on your processor board

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Thonny

Thonny is an IDE for Python which has provisions for Micropython.

Under Tools → Options button you can select the type of

Python interpreter you intend to use.

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Flashing Micropython

Compiling a new version of Micropython is substantially much easier with Thonny.

You still need to install esptool first. You just select your port and firmware then install.

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IoT Hello World program

A \x93Hello World\x94 program, just printing \x93Hello World\x94 on the screen

does not look very exciting.

However, this is generally used to verify that the infrastructure

Compiler, linker, downloader, flash program

are working correctly

In embedded systems printing can be quite complex

and a blinking LED is used instead.

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Switching on and off a LED

The ESP32-WROVER-B have a \x93user LED\x94 connected to GPIO 19.

How do we control this LED?

Define that the LED is connected to GPIO 19
Program this pin as output
Write a logic 1 to the pin to switch it on
Write a logic 0 to the pin to switch it off
The logic state may be inverted if the LED is active low

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Micropython hardware functions

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The machine.Pin class

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Switch the LED on, version 1

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Switch the LED on, version 2

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The blinking LED

Now we put the code into a script and run it

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Changing the light intensity

The LED is connected to a digital line which can only be set to 0 or Vcc.

How can we change the light intensity and dim the LED?

The light intensity depends on the average current flowing through the LED.

The answer is PWM: pulse width modulation.

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PWM in Micropython

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Our PWM implementation

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The WS2812B LED

A more complex LED:

rgb LED used in LED chains.
each ws18b12 contains the 3 colored LEDs and a controller.
Can be cascaded and individually addressed, depending on its position in the chain
Needs precise timing
To use it we pass through the neopixel library built into micropython