# Pomodoro on ESP-32

Implementation of the Pomodoro technique on the ESP-32 microcontroller.

Each transition between work and rest cycle is indicated by one or multiple physical stimulus (melody and/or color).

A display indicates the progression of the timer and double as an NTP clock.

## Table of content

* [Pomodoro](#pomodoro)
* [Electronic circuit](#electronic-circuit)
  * [Schematic](#schematic)
  * [Materials](#materials)
    * [Note on the seven-segments display and shift-register](#note-on-the-seven-segments-display-and-shift-register)
* [Software](#software)
  * [Design](#design)
  * [Dependency](#dependency)
* [Tool](#tool)
  * [Seven-segment display value](#seven-segment-display-value)

## Pomodoro

Pomodoro is a time management technique that use a timer to break down task and rest period.

## Electronic circuit

### Schematic

![schematic picture](doc/schematic.png)

### Materials

|Type|Designation|Quantity|
|-|-|-:|
|System on a chip|ESP-WROOM-32|1|
|4 digit 7 segment display|HS420561K-32|1|
|8-bit shift register|SN74HC595N|1|
|Transistor|PN2222|4|
|Diode||3|
|Passive buzzer||1|
|Momentary Switch||1|
|Resistor|220 Ω|11|
|Resistor|4.7 kΩ|4|

#### **Note on the seven-display segment and shift-register**

You might have notice that it's not the prettiest way to use a 4-digits seven-segments display.

Initially I wanted to use one shift-register per digit, but as I found only one SN74HC595N on my parts bins, I ultimately decided to make do. The result is a bit messier but works.

## Software

### Design

This software make use of the two core of the ESP-32, and it's FreeRTOS implementation to have two tasks:

1. Display the time remaining on the clock and use interrupt to count each second passed.
2. Alarm the user of a transition between task and rest with the use of melody and visual cue.

### Dependency

Ignoring the common library use in almost every project (like `stdint.h`,  `Arduino.h`, `esp32-hal-ledc.h` or `HardwareSerial.h`), the code make use of:

* [pitches.h from arduino](https://github.com/arduino/arduino-examples/blob/main/examples/02.Digital/toneMelody/pitches.h) to create melody using the piezo speaker. Included in [lib/pitches.h](lib/pitches.h) for ease of deployment.

## Tool

### **Seven-segment display value**

To ease the transition between physical segment and binary/hexadecimal code, I created a small HTML tool [tool/SevenSegmentDisplayValue.html](tool/SevenSegmentDisplayValue.html).
![segmentDisplayConverter.html in action](doc/tool_SevenSegmentDisplayValue.png)