ButtonBox

A programmable button box project using Arduino and NodeMCU combined

Description

The idea is to combine the capacities of an Arduino Micro with those of a NodeMCU 8266 for building a programmable button box. Here is what we take from the two worlds:

large number of input ports (Arduino)
USB keyboard emulation (Arduino)
Easy to program (Node)
WiFi (Node)
Screen (Node)

Note that most of the code for the NodeMCU is taken from Zuzu59 repository

The loop:

Arduino listen for a button to be pressed;
Sends a message via (software) serial port to the NodeMCU;
NodeMCU translate the button code into a string;
NodeMCU sends the string back to Arduino via serial port;
Arduino forwards the string to the computer as if it were typed into a keyboard;

Extra:

A simple web interface let the user interact with NodeMCU and change the correspondence between key press and output string. Several programs can be stored and possibly selected with a dial with visual feedback on the oled screen.

Progress

This repo is intended as a progress log. Therefore it will contain a lot of code that will not be used in the final version.

Firt step

First step was to enable testing of the two modules independently. This can be done with the help of the serial to usb module that has the following pin diagram.

Serial-USB module connection

Connector	Arduino	NodeMCU
4	12	d8
5	11	d7
8	GND	GND

Therefore, later I expect to connect (TO BE CONFIRMED).

Arduino 12 with NodeMCU d7
Arduino 11 with NodeMCU d8

Once connected, we can see the other side of the serial connection from the computer using a command like the following:

screen /dev/cu.wchusbserial1410 4800

where the device needs to be adapted to the situation (on my laptop the USB port on the left and the one on the right tend to take /dev/cu.wchusbserial1420 and /dev/cu.wchusbserial1410 respectively).

Note that analog pins are also digital pins. Therefore they can also be used for the serial link or for buttons.

Directories

{Arduino,NodeMCU}/01_minimal_serial is a simple ping/pong script taking input from the serial port and sending a reply;
Arduino/02_keypad_log is a program that detects a button press and logs it on the standard serial port;
Arduino/03_keypad_serial_log is similar to 02 but sends the info about the pressed button also to the other serial port (the one that is supposed to be connected to the NodeMCU);
Arduino/03_keypad_encode a more complex version of 03 where arduino waits for a full reply from Node and prints the answer to the standard console;
{Arduino,NodeMCU}/04_keypad_encode a variation of the previous one trying to understand why we get extra chars. Turns out, it was the standard print of Node that goes to the serial port too. There two options:
1. remove all prints (cumbersome and sad);
2. redirect output somewhere else (or just dev-null it when serial port is active)
{Arduino,NodeMCU}/05_encode_keyboard very first working prototype: Arduino sends a message with the keypad number (one byte), NodeMCU reply with the number in english text format, Arduino send it to the computer using the keyboard library

Code

Buttons can be mapped to various types of input for the keyboard:

Single Key key stroke for a printable character;
Special Key a key stroke for a non printable character (e.g. ESC key);
Modifier Key;
String (sequence of characters possibly followed by a return);
Pause

We need a codec to encode all this that can be easily generated on the gui and also parsed on the arduino.

Use sort of brackets ?

  <SpecialChar or Modifier Name> (more than one char)
  <[ModifierCharName]>
  <K> type char K
  <_._>  <_.._>  <_..._>  short, medium, long pause
  <> release all
  "string"

Or first byte as a switch ?

May be easier if for each key we have a given number of code lines. Each line contains a first byte for selcting the type of message and the message itself. There will be two type of messages: text for sending full strings with Arduino's keyboard.println(), and key for sending simple key combinations like CTRL-A. We need multiple lines because tasks might require a sequence of key combinations possibly mixed with text. For example, the task write something into the chat requires first to send a combination for activating the chat and then to type the text into the chat itself.

The messages will always be in the form of a null ("\0") terminated string where the first byte is either "T" or "K" (for text and key message respectively). The rest of the string will be treated as follow:

text string is sent unchanged with keyboard.print()
key string is split into substrings (separator to be defined). If substring is one char long, then it is interpreted as standard printable char, while if it is two bytes it is interpreted as hex code for Keyboard Special keys.

GUI

In order to preserve memory, logic should be moved to JS with very simple HTTP rest api. Programs will be stored to file (e.g. prog_01.json).

list programs: just send a list of json files
post(data) => Create new program, return index of new program
get(program id) => Read program with given id
put(id, data) => Update program with given id (overwrite file);
(?) delete(id) => Delete program with given id

multiscan/ButtonBox