Unidirectional Communcation between 2 Arduino boards

original article

   I want to send many commands using just 1 wire (and ground) so I use 2 Arduino boards.
   Base schematic for unidirectional communcication between Arduino boards is

and you can test this simple mode communication using info from article Tech Thurday #005: Arduino to Arduino Serial Communication.
   For sender (transmiter) I use a keypad with LCD1602 shield (see https://www.dfrobot.com/

This shield has the schematic

   Test schematic is

and sketch for transmiter is transmiter_v0.ino and sketch for receiver is receiver_v0.ino.
   If you have v.1.1 shield you must have

and for v.1.0

   I made Unidirectional Communication between 2 Arduino boards

  The states for this system are:
- all button are free (not pushed)

- if you push SELECT button

- if you push LEFT button

- if you push RIGHT button

- if you push UP button

- if you push DOWN button

 

Measure times using millis()

   If you need to find the time what a button is pusshed or you want to use one button for made more function (short or long push / short, medium or long push) it can use millis() function with Arduino  language.
   Information for this thechnique (method) I found it on Doz's Blog.
   For test, I use a simple schematic (one button) and pushtime1button.ino program (sketch).

    For understand more ok the style of use, I tested also with 2 buttons, using pushtime2buttons.ino sketch.

     I made a short movie named measure times using millis() where is mase some tests:

Animated adjusting clock with termomether and hygrometer on 7 segment led display

  After a discution with GeoMar, I decided to made a clock with few animation when change informations on 4 digit 7-segment led display.
   Last test was made be me with LFD080AAG-103 led display, who is with common anode:

    Base schematic is used in some projects

but I put control for brightness (automatic or manual)

or 

and 2 buttons for adjust clock and data

    Sketch multiplexed_scroll_clock3.ino made a clock who has next informations:

- clock, with flash led for beat seconds, about 10 seconds

- temperature, about 2,5 seconds

- relavive humidity for air, about 2,5 seconds

- data (day and mounts), about 2,5 secods

   Brightness can be control in 1024 steps when it used photoresistor or in 2 (minumum or maximum) wirh switch

   If is pushed MENU button, clock enter in adjusting mode, first for hour, so, you will see hour flashing and can be increase value by pushing + button, but if hour is 23 and + button is pushed, value for hour is 00...

   If is pushed again MENU button, clock enter in adjusting mode for minutes, so, you will see minutes flashing and can be increase value by pushing + button, but if minutes are 59 and + button is pushed, value for minutes are 00...

   Next push of MENU button go to year changes, from 2018 to 2049

After that, if push again MENU button, you can change month (1 to 12)

and if push again on MENu button you can change day of month (just day flash)

After a new push of MENU button, system enter in clock mode (normal mode).

    I made a movie for see how clock show the datas and how can be changes clock and data:

Note: Schematic work for small led display with common anode

or common cathode

   Base schematic is similar

   If you want to see in night just clock and temperature, when is day all informations (clock, temperature, relative humidity and data) you must upload sketch multiplexed_scroll_clock3a.ino !

Thermostat for recycle pump at heating system

   For heating system using wood or another solid combustible materials who use recycle pump, I design a simple thermostat to power the pump just if water temperature is bigger than desired temperature.
   Schematic is simple

   Tom, a friend of mine, made practical system with Arduino Nano on PCB:

Using DS18B20_thermostat.ino sketch system work like in this photo:

- when temperature of heating water is bellow than desired temperature pump is off

- when temperature of heating water is bigger then desired temperature pump is powered.

Tom made more tests with sistem:

    Tom made 2 movie (speak in romanian language):

- termostat cu Arduino

- Termostat pentru pompa de recirculare la centrala pe lemne