Anything would help really. My goal is to have this website ad free and so you can enjoy my content without having to look at ads. Thank you



1. Introduction
2. 3D Renderings
3. Schematics
4. Arduino Code
5. Conclusion / Future changes
6. Download original files


Now this might seem like it was a complete waste of time to try and reinvent the wheel with creating my owm custom BMS solution. You can buy them on ebay or alibaba or banggood for super cheap and it seems like a plug and play solution.

One problem I see with this, at least for me, is that I dont completely trust those cheap BMS system.  I like to buy something that is reasonable as well as trusting that it will safely protect my cells from unbalancing.  Another this is that I like to have flexibility with how I balance my cells or anything else.

Now this is where the custom arduino BMS came into play.  I’ve designed this bms to handle a 4S battery pack so upto 16.8V fully charged and 14.8V nominal.  The balance discharge current can be adjusted by simply replacing the discharge resistor with any value you wish. Just to add this does not have over current or over voltage protection..yet 🙂 I’m currently working on an add on for this so stay tuned for that future update.

Lets get started with all the cool details for this arduino bms.


Here i just wanted to show you the 3D rendering images of the final board.  The rendering was created using kicad and its pretty nice actually for an EE cad software.

The heart of this system is the atmega328P running the minicore arduino bootloader[1]. From here you have the 4 balancing passive resistors to the right of the board.  The best part of this project is that you can replace these resistors to any value you want to customize the balance current.

The one thing that this does not have is overvoltage and overcurrent protection but that will be a separate circuit later on ;).

Now we can talk about the main features below in the schematic section.


Below are images of the full schematics for this project:

The first page of the schematic files is a hierarchy block level of the system to help understand how a lot of these subcircuits are linked together.  Below I’ll breakdown all the pages and what exactly they do.

1. Hierarchy Block:

  • This is the overview block level that links the subcircuits on the separate pages.  I normally like to design my projects this way if I have more than 2 subcircuits because its easier to see how things are working together

2. Power Supply

  • This section is just the power supply section to power the arduino.  This is a high differential buck converter.  The input voltage can go up to 36V and output down to 1.8V with an active quiescent current of only 190uA.  Now the most important part is the quiescent current because we are trying to eliminate any wasted current since this is for a battery operated system and we do not want to drain the batteries faster than needed.

3. MCU

  • The MCU page has the Atmega328P and all the corresponding IO related to it.  Im using A0-A3 to measure the batteries via a resistor divider
  • This page also includes the external reference voltage used instead of the built in 1.1V from the atmega328p. Its a 1.25V external voltage reference that has a better tolerance at a range of temperatures.

4. Balancing Circuit

  • This page has the balacing circuit which is incharge of discharging the battery cell that has a higher potentional.  The heart of this is a bidirectional N-channel mosfet that allows current to flow in both directional either during discharge or during charging.

5. Connectors

  • This page has the power pin connectors and the BMS pads that connectors to the lithium cells.

Now that we’ve gone through the schematic lets go into the second most important part and that is the arduino code.


Now probably the second most important part is the arduino code that will control the mosfets triggering the discharge when a preset voltage difference is hit.

#include "Adafruit_SSD1306.h"

/* Revision: A9
 * Written by: Steven Guzman
 * Date: 7/10/2018
 * Description: This is a customizable BMS system for a 4
 *              cell lithium ion pack.

#include "Wire.h"
#include "avr/wdt.h"<span id="mce_SELREST_start" style="overflow:hidden;line-height:0;"></span>

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define NUMFLAKES 10
#define XPOS 0
#define YPOS 1
#define DELTAY 2

// This variable is used for checking on
// whether the OLED screen is attached or not
int check = LOW;

// Sampling number for analog read values.
// Will use this sample size to calculate a
// better estimation of the analog value
int samples = 100;

// This is the max difference that the cells
// can achieve in respect to each other
float tol = 0.03;

// To temporaly store analog values from the
// cell voltages to average out later with
// the number of samples taken
float temp_cell[4];

// Float array to store unconverted cell values
float cell[4];

// Variable array to store converted voltage
// values for cell measurement
float B[4];

// Variable array to store voltage differences
// between cells
float diff[4];

// Variable used for digital output
// signals
int BAT[4];

// Variable used for storing the cell pack
float PACK = 0.000;

// Scaling factor used for converting
// the scaled down analogread values to there
// actual values from the voltage divider
float scale0 = 0.25;   // 10k/(30k + 10k)
float scale1 = 0.125;  // 10k/(69.8k + 10k)
float scale2 = 0.083;  // 10k/(110k + 10K)
float scale3 = 0.0625; // 10k/(150k + 10k)

#if (SSD1306_LCDHEIGHT != 32)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");

void setup()

  analogReference(EXTERNAL); // Configure reference voltage for
                             // external 1.25V

  // After switching to external reference you
  // need to read a value a couple times before
  // the reference has stabalized.

  // Setup up watchdog timer to reset
  // after 4 seconds

  // Variables to set the digital output
  // pins 1-4
  BAT[0] = 5;
  BAT[1] = 6;
  BAT[2] = 7;
  BAT[3] = 8;

  // Setting digital pins to output configuration
  pinMode(BAT[0], OUTPUT);
  pinMode(BAT[1], OUTPUT);
  pinMode(BAT[2], OUTPUT);
  pinMode(BAT[3], OUTPUT);

  // Sets the digital outputs to an initial low
  // state



void loop()

  Wire.requestFrom(0x3C, 1); // Pings OLED screen

  // If OLED pings back and check statement
  // equals 1, then initiate the OLED screen
  // and reset the check value to 0 so it will
  // not continue to re-initiate. It needs to
  // initiate another request one last time
  if (Wire.available() &amp;&amp; check == HIGH )
    display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
    check = 0;
    Wire.requestFrom(0x3C, 1);
  if ( Wire.available() &amp;&amp; check == LOW)
    // Leave blank
  else if (!Wire.available())
    check = 1;

  // Sets the temp variable array back to zero
  for (int x = 0; x &lt;4; x++)
    temp_cell[x] = 0.00;
    diff[x] = 0.00;
    cell[x] = 0.00;
  // For loop used to record battery cell voltage
  // information and used later to average out
  // the readings

  // Using true RMS calculation for computing a
  // better average estimate for multiple samples.
  for (int i = 0; i &lt; samples; i++)
    temp_cell[0] = temp_cell[0] + sq((analogRead(A0)/scale0)* (1.249 / 1024));
    temp_cell[1] = temp_cell[1] + sq((analogRead(A1)/scale1) * (1.249 / 1024));
    temp_cell[2] = temp_cell[2] + sq((analogRead(A2)/scale2) * (1.249 / 1024));
    temp_cell[3] = temp_cell[3] + sq((analogRead(A3)/scale3) * (1.249 / 1024));
  cell[0] = sqrt(temp_cell[0] / samples);
  cell[1] = sqrt(temp_cell[1] / samples);
  cell[2] = sqrt(temp_cell[2] / samples);
  cell[3] = sqrt(temp_cell[3] / samples);

  // Scale up the cell values and then convert to
  // to voltage values
  B[0] = (cell[0]);
  B[1] = ((cell[1] - cell[0]));
  B[2] = ((cell[2] - cell[1] ));
  B[3] = ((cell[3] - cell[2] ));
  PACK = B[3] + B[2] + B[1] + B[0];

  // Compares each cell voltage to each other and then finds the
  // lowest cell value.  Then it stores the difference between the
  // lowest cell and the remaining cells for comparison
  if ( (B[0] &lt;= B[1]) &amp;&amp; (B[0] &lt;= B[2]) &amp;&amp; (B[0] &lt;= B[3]))
  diff[1] = B[1] - B[0];
  diff[2] = B[2] - B[0];
  diff[3] = B[3] - B[0];
  else if ((B[1] &lt;= B[0]) &amp;&amp; (B[1] &lt;= B[2]) &amp;&amp; (B[1] &lt;= B[3]))
  diff[0] = B[0] - B[1];
  diff[2] = B[2] - B[1];
  diff[3] = B[3] - B[1];
  else if ((B[2] &lt;= B[0]) &amp;&amp; (B[2] &lt;= B[1]) &amp;&amp; (B[2] &lt;= B[3]))
  diff[0] = B[0] - B[2];
  diff[1] = B[1] - B[2];
  diff[3] = B[3] - B[2];
  diff[0] = B[0] - B[3];
  diff[1] = B[1] - B[3];
  diff[2] = B[2] - B[3];

  // It enables the balancing protocol for a given cell that has a
  // greater voltage difference from the lowest cell and the set
  // tolerance.
  for ( int x = 0; x  tol )
      digitalWrite(BAT[x], HIGH);
      digitalWrite(BAT[x], LOW);

  // text display tests



Lets break down this code in order to understand my thought process behind this.arduino_code_sampling_section

  1. The samples variable is used to create an average sampling of the battery cells to eliminate any noise issues.  The averaging technique I used in this project is a little different than most but I will explain later on
  2. The next variable is the tol variable.  This variable is the maximum voltage different between the lowest cell and the rest of the cells in the 4S pack.  Currently its set to a maximum of 30mV difference but this can be set to a minimum of 10mV because of the 8-bit adc on the arduino.


  1. Here is the scaling factor for the adc from the cell measurements.  We have different values because in order to get the best accuracy measuring in reference to ground, different values were needed for measuring cell 1 which has a max of 4.2V and cell 4 which measures a max of 16.8V.


  1. This portion of the code is mainly for the OLED screen.  It allows for the screen to be removed and re attached without having to reset the arduino.  Before you had to initialize it in the setup but with this loop it is initialized in the main loop when it detects the screen.


  1. Now this section is averaging the adc values from all 4 cells to get a best measurement of the cell voltage values.  Instead of using the traditional sample 25 and take the average, I’m using a true RMS calculation that will give you a slightly better voltage measurement that just taking the average.  It will be at a closer measurement to your multimeter than using average sample.



Here is the final PCB:

I’m pretty excited to do more testing on this and I will post my technical review later on that includes current consumption, maybe a mini manual on how to use it or change values for your own build.

Again this does not include an over voltage or over current protection circuit but I decided to make that a separate board with its own controller in order to make the board as small as I could and isolate the two circuits as a redundancy.  I’m still making some tweaks and might make another revision but all in all I’m very happy about it.

Some current issues that I know off.

  1. You might have to calibrate with a known good multimeter.  The arduinos ADC has some weird issues with analogPin A2 measuring higher than the rest.  I added a calibration value in the code to help with that.



Download here.

For the Bill of Materials, I’ve embedded the datasheets for some of the major components in case you wondered why the file is larger than it should.



1. Minicore bootloader

Project – GRBL Controller Board


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1. Introduction
2. Bill of Materials
3. Schematic
4. 3D Redering
5. Final Thoughts
6. Download Original files


With all the low cost CNC machines out in the market, there is also an abundant of GRBL shields for the arduino platform. Like always, I’m always looking to for ways to customize and improve whats in the market.

What I’ve created is a slightly better GRBL controller board for low cost CNC machines. This uses the Arduino Nano instead of the Uno as this allowed for more flexibility on the size of the board. It also integrates the relay switch for the spindle with an integrated flywheel diode to avoid over voltage spikes when the spindle is first turned on.

Below I’ll discuss in more detail along with the files you need to create this board.


Click here to download the bill of materials


Here in the schematic you can see a couple of items that are different from the traditional ebay/amazon grbl shields. First of all this is not a shield per say but more of a standalone controller board.

  • Since the capacitors that are used to filter the stepper drivers are 35V rated, I’ve limited the input voltage to 24V
  • I’ve added a TVS diode at the power input that protects from over voltage spikes.
  • Used better output connectors for the stepper motor drivers
  • Added 0.1uF capacitor for the probe pin for autoleveling
  • Added x3 5V rail connectors
    • One thing to add is that these connectors are taking power from the USB port and should not be loaded more than 0.2A combined
    • I added these for low current 5V noctua fans to cool the stepper drivers
  • Added relay control on the main board to eliminate adding external relay switch for the spindle.
    • some newer versions of the grbl software, I believe v1.1 has the spindle pin and z-axis switch so thats why I included the option to switch between the two
    • I believe you can switch this back in the firmware of the grbl settings. But none the less the option is there
  • The relay controller also includes a 1000uF and a flywheel diode to prevent voltage spikes on turn-on


Here is a 3D Rendering from Kicad of the board. I’ve added this rendering because I thought it looked really cool.

Here is a picture of the final board below:

Below is the board fully soldered and it works amazing. I will add some images of the quality of boards my machine makes with the new controller board.

Future revisions of the board I will increase the 5V rail to supply up to 1A of current for high current draw fans and order accessory’s. Also, I will try to route out the limit switch pins. This will require me to remove the z-limit switch pin that connects to the spindle control but that should not be an issue.

If you have any comments or suggests please feel free to send them my way.

Thank you!!

Download original files here.

I have about 8 extra PCB boards that I’d be willing to sell. Let me know in the comments below if that’s something you’d like to buy

Project – DC Power and Efficiency Meter


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1. Introduction
2. Bill of Materials
3. Schematic
4. Code
5. ME Cad design
6. Final Thoughts
7. Download Original files



This is a fun little project that actually took me awhile to put together.  What makes this project interesting and useful is that it will display your voltage, current, and power of any device you plug it into.  What also makes this project useful is that it will calculate the efficiency of your device for example a dc dc converter.

The heart of this project is two INA219 high side current sensors from Texas Instruments.  With this sensor you can measure up to 26V DC and up to +/-3.2A with a 0.1ohm shunt resistor (if you swap out the shunt with a 0.01ohm shunt you can measure up to +/-32A)


Click Here for bill of materials


Here you can see a block diagram showing how I connected the different boards to create this project. Since I used my CNC machine to create the boards, it’s always much easier to separate the circuits into different boards for routing.

The main board consist of an arduino pro mini to keep the footprint as small as I can and also host a 5V boost converter being power from the 18650 lithium ion battery.  In order to charge the battery without having to remove it from the enclosure, I decided to add a lithium ion charger board that connects in parallel with the battery.  Its powered by a 5V USB mini connector and can be bought on amazon.

The second board host x2 INA219 high side I2C current, voltage, and power sensor by Texas Instrument.  This IC is an amazing little thing because it takes a lot of the number crunching away from the Arduino and just sends the data over I2C that you need.

The final piece of this is the I2C liquidcrystal display for the arduino.  I used this library here for the display.  Make sure you connect the display and run an i2c address scanner on the examples for arduino because sometimes the displays have a different address than the default one listed.



 * Name: Steven Guzman
 * Date: 2018/03/18
 * Description: This is a DC power meter that measures input and output
 *              power and calculates the efficiency of the system.
 *              It can also measure voltage and current of one or two
 *              voltage sources

LiquidCrystal_I2C lcd(0x3F,20,4); // Set the LCD address

 * Below are the array values to store the measurements
 * and then used to convert float to string
char float_volt1[8];  // voltage 1 array
char batt0[21];
char float_volt2[8];  // voltage 2 array
char batt1[21];
char float_current1[8]; // current 1 array
char curr1[21];
char float_current2[8]; // current 1 array
char curr2[21];
char float_eff[8];  // efficiency variable array
char line6[21];
char float_batt[6]; // battery voltage array
char line5[21];

// Analog sampling number
int sample = 20;

// Inialize current sensors.
// ina219_A default address is 0x40
Adafruit_INA219 ina219_A;
Adafruit_INA219 ina219_B(0x43);

// Variables to store current sensor data
float busvoltage1 = 0;
float busvoltage2 = 0;
float current_mA1 = 0;
float current_mA2 = 0;

float batt = 0.00;

void setup()




void loop()
  float xbat = 0.00;

  for(int x=0;x<sample;x++)
    batt = analogRead(A0);
    xbat = xbat + batt;
  // Read voltage levels from the voltage address
  // of the IN219 on both ICs
  busvoltage1 = ina219_B.getBusVoltage_V();
  busvoltage2 = ina219_A.getBusVoltage_V();

  // Read current levels from the current address
  // of the IN219 on both ICs
  current_mA1 = ina219_B.getCurrent_mA();
  current_mA2 = ina219_A.getCurrent_mA();

  // Average out the analog measurements
  // for the lithum ion battery voltage
  // sensing
  xbat = xbat/sample;
  float battery = xbat * (5.00/1024);
  sprintf(line5, "Battery:%-5s",float_batt);
  char temp3[] = "V";

  // Convert float values into an char array to
  // better update on the lcd screen without
  // having to use the lcd.clear function
  sprintf(batt0, "V1:%-5s",float_volt1);
  char temp2[] = "V";
  strcat(batt0, temp2);

  sprintf(batt1, "V2:%-5s",float_volt2);
  char temp1[] = "V";
  strcat(batt1, temp1);

  // Convert mA to A readings
  float C1 = current_mA1/1000;
  float C2 = current_mA2/1000;

  sprintf(curr1, "C1:%-5s",float_current1);
  char temp4[] = "A";
  strcat(curr1, temp4);

  sprintf(curr2, "C2:%-5s",float_current2);
  char temp5[] = "A";
  strcat(curr2, temp5);

  float power1 = busvoltage1 * C1;
  float power2 = busvoltage2 * C2;

  float eff = (power2/power1)*100;

  sprintf(line6, "Efficiency:%-7s",float_eff);

   * Display on LCD screen all the values.
   * I used char arrays to update the values on the
   * screen.  Using the lcd.clear caused flickering
   * and was annoying.  With char array you can include
   * the units and it will update properly and not
   * overright the units.








There might be some issues with how wordpress displays the arduino code but I attached the original files at the end this tutorial.

As mentioned before, the libraries used here I obtained from other sources:

  1. Liquid crystal display library
  2. INA219 adafruit library


I designed the enclosure in fusion 360 and printed the both with matterhackers pro series PETG red.  I used a monoprice maker select v2 to print this enclosure.

Here is the step file for the enclosure


This was one of my favorite projects yet because the design alone makes me feel accomplished learning everything on my own.  I still feel like I can make some upgrades to how I mount the internals and to be honest, I really rushed this part because I wanted to finish it.

Some upgrades I’m considering is using the arduinos internal 1.1V reference with a voltage divider to measure the battery voltage because it wasn’t as accurate as I wanted it to be.

Thank you for visiting and reading my project. if you have any questions or comments or suggestions please don’t hesitate to ask.


Original files

Electronics: FTDI USB TO UART


Anything would help really. My goal is to have this website ad free and so you can enjoy my content without having to look at ads. Thank you





1. Introduction
2. Bill of Materials
3. Schematic
4. Oshpark
5. Final Thoughts
6. Download Original files


With the Arduino mini, there is a need for a USB to UART controller to upload your sketches and this could also be used for the ESP8266.

This project is inspired and based off the Sparkfun’s FT231X breakout board design.  I’ve created this project because 1. I like designing and soldering electronics 2. Try to create a cheaper alternative to the popular FT232RL and also add 1 or 2 features to the current FT231X breakout board.


For the bill of materials, its pretty straight forward.  I’ve attached links to digikey for each component as I find them easier to order from but you could also get the parts from arrow or mouser as well.



Component Description Part number Quantity Link
47pF, 0603, 50V C1608C0G1H470J080AA 2 Digikey
0.1uF, 0603, 25V CGA3E2X7R1E104K080AA 4 Digikey
10uF, 0805, 6.3V TCJN106M006R0250 1 Digikey
Micro B Connector 10118192-0001LF 1 Digikey
6-pin Header M20-7910642R 1 Digikey
N-Channel FET BSS84-FDICT-ND 1 Digikey
27 ohm, 1206 RC1206JR-0727RL 2 Digikey
10k, 0603 RT0603DRD0710KL 2 Digikey
FT231X, SSOP-20 FT231XS-U 1 Digikey


Below I’ve attached an image of the schematic but i’ve also attached the original kicad files and a PDF version of the schematic at the end of the post.


If you feel like you want to get this board made, I’ve attached a link to my oshpark project.  With oshpark, I find they make great quality boards at a great price for small sized boards.

Order from OSH Park


I know this was a short post and project but I found it important to share another option for those’s who want to find a cheaper solution and want to learn along the way.  You can find a lot cheaper solutions on amazon that are china made but i’ve read stories in some cases that they were not genuine FT232RL ICs.  If you wish to build your own, its very easy and rewarding at the same time.

In the next revision I will add LEDS for TX and RX indication as for this version I eliminated to save some cost and space.

Hope you enjoyed this post, THANK YOU 🙂





Anything would help really. My goal is to have this website ad free and so you can enjoy my content without having to look at ads. Thank you




1. Introduction
2. Bill of Materials
3. Block Diagram
4. Schematics/CAD DESIGN
5. Assembly
6. Final Thoughts/ Improvements
7. Download Original Files



Arduino and the implementation of GRBL has allow for amazing things to be created.  One of those things are low cost CNC machines that enable us to create anything we want.

I bought myself a low cost CNC engraver from amazon and after modifying it, it has been one of my best investments because as en electrical engineer I can create PCB boards to test my designs here at home and verify before getting them sent out. One problem I usually have is that I use my laptop to run the gcode software and my laptop is really big and sometimes a hassle to keep on my desk.

My solution was to create this project and make a standalone CNC machine controller to run the gcode software in a compact package.  I tried fiddling around with using a raspberry pi 2 as my main PC but I’m still a beginner with raspberry pi’s and I had issues getting the settings right.  My next option was to use a windows based machine and luckily I found just the solution.

In this tutorial I will explain how I put this together and what improvements could be made.


Component Quantity Link
Windows computer stick 1 Amazon
Wireless keyboard/mouse 1 Amazon
DIY HDMI male adapter angled 1 Adafruit
DIY HDMI female adapter 1 Adafruit
DIY HDMI Ribbon cable 20cm 1 Adafruit
3.5 inch Screen 1 Amazon
Left angled micro usb cable 1 Amazon
Top angled usb 3.0 extension 1 Amazon
USB Board
USB Female Connector 2 Sparkfun
5VWM TVS Diode 1 Digikey
0.1uF 50V X7R 1206 1 Digikey
1uF 25V X7R 0805 1 Digikey
10uF 16V X5R 0805 1 Digikey
100 OHM 0.1% 1/8W 0805 2 Digikey


Visio_blog - block diagram

Here is the block diagram for how this project is wired.  With the exception of the enclosure itself and the usb power board, everything was bought ready to go.  I’ve added a fan as a just in case because the computer stick does generate some heat so the fan will prevent the system from over heating but so far it does not seem to be an issue with heat and therefore is an option.

The 5V and 12V supply are coming from my 24V power supply that powers my Arduino GRBL shield.  What I did was use two step down converters 1) For 5V step down and 2) For 12V step down.  I realized this might not be idle but it is my first revision of this project.


The only schematics I have is for the USB power board and I created that using Kicad.  The board was basic, since both the screen and the windows computer stick ran on 5V via micro USB, I needed to distribute power from one source into two loads.  To add some safety, I did add a TVS 5VWM diode to prevent over voltage spikes from destroying the devices along with some filtering capacitors.

Electronics_pdf - cnc usb power board-1

If its a little blurry don’t worry because all original files will be included in a download link at the end.

Now for the enclosure, I designed it using Fusion 360.  Honestly, I am not a Mechanical engineer/Designer so this was my first attempt at designing something in a CAD software.  Mine you its really just a box but Fusion 360 makes it really easy to design for someone who had no prior experience.

I designed this in two pieces:

  1. The bottom portion of the enclosure:CAD_pdf - Enclosure Drawings-1
  2. The Lid for the enclosure:CAD_pdf - Lid Drawings-1

For material used for making this enclosure, I used my Maker Select V2 3D printer with PETG filament for the temperature resistance and flexibility.

I will include the STL files so you guys can 3D print this yourself.


Now for the fun part, putting this thing together and hoping everything works without the magic white smoke lol jk.  This was actually very easy to put together though there were a couple of design hick ups.

Since I wanted to get the print out as fast as possible, I sacrificed quality of the print which is why it looks the way it does but its very function.

As I mentioned I did have some design issues after I was putting this thing together.  If you look at image 3, you can see that the usb power board is tilted up and thats because I placed the cooling fan to close.  The board was able to fit but I could not connect anything because the fan was blocking the connectors.

I decided to use hot glue to hold everything down because it wouldn’t be a DIY project if hot glue wasn’t involved.

In image 4, you can see I used some basic terminal block connectors to attach my 5V and 12V supply.  You can also see the USB port to connect the arduino grbl controller board.


Overall I enjoyed putting this project together.  It’s made my project efficiency increase dramatically because I don’t have to take it out and set it up every time I want to make a board.

With anything we do, there’s always room for improvements.  In a future version of this project I plan to improve the way I connect my external 5V and 12V supply instead of using the terminal blocks.  I might possibly use some type of molex connector that can easily detach.  To reduce the amount of external connectors, I could switch out the 12V fan with a 5V fan and run it with only one step down converter.  I’m going to also move the fan placement so that I do not have to angle the usb power board.


Bill of Materials

KiCad files

3D STL files

PDF Documents

Thank you for visiting and I hope you enjoyed this project.

Please leave a comment and let me know about your thoughts, improvements or any issues you see with this post.  All comments are welcomed 🙂

Arduino – Garage Door Indicator

First I would like to say thank you in advance for visiting my site.  My goal is to help anyone who loves to work with electronics.






1. Introduction
2. Bill of Material
3. Block Diagram
4. Schematics
5. Arduino Uno sketch and upload
6. ESP8266 sketch and upload
7. Final thoughts
8. Download original files






I don’t know about you guys but when it comes to closing my garage door I always seem to forget.  Most of the time I don’t even notice until the night before I head to bed.  I was getting tired of leaving it open so then I was inspired to create this project.

The garage door indicator project essentially sends you a text if the garage door is left open for more than 5 minutes.  It uses an arduino, ESP8266, and IFTTT to remind me that I left it open.

Lets get started!


Board Part Quantity Link
Arduino Board
 Arduino Pro Mini 1 Amazon
ESP8266 Board
ESP8266 ESP01 1 Amazon
RC1206JR-0710KL 4 Digikey
C1206C104K5RAC7867 2 Digikey
Boost Converter #1: Arduino Board
GRM21BR61E475MA12L 1 Digikey
MCP1640T-I 1 Digikey
GRM21BR61C106KE15K 3 Digikey
RC0805JR-07560KL 1 Digikey
TC33X-2-105E 1 Digikey
MSS5131-103ML 1 Coilcraft
Boost Converter #2: ESP8266
AAT1217ICA-3.3-T1 1 Digikey
GRM21BR61E475MA12L 1 Digikey
GRM21BR61C106KE15K 3 Digikey
RC1206JR-071ML 1 Digikey
MSS5131-472ML 1 Coilcraft
Switch: ESP8266 Power
DMG2305UX 2 Digikey / Arrow
2N7002-7-F 1 Digikey
RC1206JR-0751KL 1 Digikey
RC1206JR-0710KL 1 Digikey


Electronics - Garden_Block diagram_01

Here the block diagram gives you a general idea of how this is connected together. I’ve made this project very modular so upgrades and replacements are easy to do.  I decided to go with two boost converters because the ESP8266 has a lot of noise issues that always messed with my arduino board and so separating the supplies and the controllers from each other did the trick.


Below I’ve listed all the schematics that are associated with this design.  I’ve designed this project to be very modular because I CNC mill all the boards and it makes it a lot easier to work with.

If you click on the schematic images, i’ll take you to the pdf version that you can download.

Arduino nano board:

Arduino Board

ESP8266 Board:

Electronics - ESP8266 Board

Boost Converter #1:

Electronics - MCP1640

Boost Converter #2:

Electronics - AAT1217

Switch: ESP8266 Power:

Electronics - Switch ESP8266


Here is the arduino sketch used in the garage door project.  Essential the arduino nano is used to first sense the status of the garage door and second to wake up the ESP8266.

The way this sketch is written is the arduino is put into an 8 second sleep state because thats the longest the watchdog timer will fire.  This is then looped in that adds up to 5 minutes.

The reed switch is connected to the interrupt pin 2 on the nano and is used to wake up the arduino  when the door is open.  Then a counter will start counting and when 5 minutes are up that the door is left open, this will activate the switch that will turn on the ESP8266.

#include "LowPower.h"
int ESP8266 = 10;
int Open = 2;
int x = 0;

void setup()

void loop()
  // put your main code here, to run repeatedly:
    // Low power sleep mode is used here to put the arduino
    // in an 8s sleep state
    if (digitalRead(Open) == HIGH)
      x = x + 1;

    // Here is the value entered that will
    // set the time it takes for it to
    // wake up the ESP8266
    // 2 minutes = 15
    // 4 minutes = 30
    // 5 minutes = 39
    // 10 minutes = 80
    if ( x == 39)
      digitalWrite(ESP8266, HIGH);
      x = 0;
    if (digitalRead(Open) == LOW)
      x = 0;


All sketches and libraries will be attached in the links at the end of the post under download files


After the arduino nano is configured to wake up the ESP8266, the next thing we will do is load the sketch for the ESP8266.

Now before we go into the sketch, we first need to setup an account with  After that is done then we need to create a new applet.

IFTTT - New Applet

Next, we click on If this:

IFTTT - If this

Next, we search for webhooks service:

IFTTT - Webhooks

After that, we create the trigger.  Here we enter “Door” as our trigger:

IFTTT - Trigger

Now we need to create the action, in this case send a text when this is activated.  We click on THAT now:

IFTTT - That

We search for SMS and click on the first one:


We now set the action, leave it as is and click on create:


Then you click finish.

In case your phone number is not set, lets go to search:

IFTTT - sms_number.PNG

And we click on settings and edit.  Here you enter your phone number you wish to receive your text:


Now the last and most important part, we need to get your “mykey” needed to link ifttt with your esp8266.

We go to search again and this time type in webhooks.  Then you go to settings and you copy the highlighted key into your ESP8266 sketch:

IFTTT - Webhooks_mykey

Now you are ready to continue to the sketch.

Here is the sketch for the ESP8266.

Original sketch was taken from this link and modified slightly for my project.

// Name: Steven Guzman
// Date: 12/13/2017
// Description: ESP8266 code for sending a message over to IFTTT that the garage door is open

#include &amp;amp;lt;ESP8266WiFi.h&amp;amp;gt;
#include &amp;amp;lt;arduino.h&amp;amp;gt;
#include &amp;amp;lt;SPI.h&amp;amp;gt;
#include "DataToMaker.h"

#define SERIAL_DEBUG // Uncomment this to dissable serial debugging

// Define program constants

const char* myKey = ""Enter your key right here"; // your maker key here
const char* ssid = "Enter your SSID wifi name here"; // your router ssid here
const char* password = "Enter your password here"; // your router password here

// declare new maker event with the name "ESP"
DataToMaker event(myKey, "Door");&amp;amp;lt;span 				data-mce-type="bookmark" 				id="mce_SELREST_start" 				data-mce-style="overflow:hidden;line-height:0" 				style="overflow:hidden;line-height:0" 			&amp;amp;gt;&amp;amp;amp;#65279;&amp;amp;lt;/span&amp;amp;gt;


bool connectedToWiFI = false;

void setup()

  delay(10); // short delay

void loop() {
  if (wifiConnected)

    if (event.connect())
       if (digitalRead(2) == HIGH)
       event.setValue(1,"Garage Door is Open, close it NOW!!");
       debugln("Connected To Maker");;

      if (digitalRead(2) == LOW)
        event.setValue(1,"Garage Door is Closed");
        debugln("Connect to Maker");;
    else debugln("Failed To Connect To Maker!");

    delay(5000); // pause for 1 second
    delay(60 * 1000); // 1 minute delay before trying to re connect

bool ConnectWifi()
  // Connect to WiFi network
  debug("Connecting to ");
  unsigned long startTime = millis();
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED &amp;amp;amp;&amp;amp;amp; startTime + 30 * 1000 &amp;amp;gt;= millis()) {
  if (WiFi.status() == WL_CONNECTED)
    debugln("WiFi connected");
    debugln("WiFi Timed Out!");

bool wifiConnected()
  return WiFi.status() == WL_CONNECTED;

void debug(String message)

void debugln(String message)

void debugln()

Here is the second file needed for the ESP8266:

#include &lt;Arduino.h&gt;
#include &lt;ESP8266WiFi.h&gt;

#ifndef DataToMaker_h
class DataToMaker
    DataToMaker(const char*, String); // constructor
    bool connect();
    bool setValue(int, String);
    void sendToMaker();
    void post();

  protected: // it is protected because the subclass needs access
    //to max distance!

    void compileData();
    WiFiClient client;
    const char* privateKey;
    String event;
    String value1, value2, value3 = "";
    bool dataAvailable;
    String postData;

DataToMaker::DataToMaker(const char* _privateKey, String _event)
  privateKey = _privateKey;
  event = _event;

bool DataToMaker::connect()
  if (client.connect("", 80))
    return true;
  else return false;

void DataToMaker::post()
  client.print("POST /trigger/");
  client.println(" HTTP/1.1");

  client.println("User-Agent: Arduino/1.0");
  client.println("Connection: close");
  if (dataAvailable)
  { // append json values if available
    client.println("Content-Type: application/json");
    client.print("Content-Length: ");

bool DataToMaker::setValue(int valueToSet, String value)
  switch (valueToSet)
    case 1:
      value1 = value;
    case 2:
      value2 = value;
    case 3:
      value3 = value;
      return false;
  return true;

void DataToMaker::compileData()
  if (value1 != "" || value2 != "" || value3 != "")
    dataAvailable = true;
    bool valueEntered = false;
    postData = "{";
    if (value1 != "")
      valueEntered = true;
    if (value2 != "")
      if (valueEntered)postData.concat("\",");
      valueEntered = true;
    if (value3 != "")
      if (valueEntered)postData.concat("\",");
  else dataAvailable = false;
#endif&lt;span 				data-mce-type="bookmark" 				id="mce_SELREST_start" 				data-mce-style="overflow:hidden;line-height:0" 				style="overflow:hidden;line-height:0" 			&gt;&lt;/span&gt;

Make sure to place the datatomaker file code above in the same directory as the ESP8266 code.


Here is the final project assembled:


This project was not designed to be pretty but since I used my CNC machine to mill out the boards I was limited to the one side.  There is an upside to designing it this way, if one or two of the boards happen to malfunction, you can switch it out.  Or if you ever need to upgrade, you can easily swap out what you need to upgrade.

I’m planning on making a professional board and consolidating the boards into one or two boards in the future but for now I’m happy with the results.

If you have any questions please feel free to comment or if you find an error or an issue with anything posted please let me know and I’ll correct it.



Project files



The arduino platform is one of the biggest and most popular platforms used for prototyping.  One of the most popular Arduino boards is the Arduino Uno and for good reasons because its very intuitive and easy to use with plenty of IO pins and analog pins.

With the Arduino uno having 28-pins, sometimes your design or project will only require a handful of IO pins and will need to be crammed into a small board.  That’s when the ATTINY85 IC comes to the rescue.

The ATTINY85 is a low-power, 8-bit AVR microcontroller.  Its a great little micro controller that can be programmed with Arduino, though it does have its limitations like a smaller 8kB flash memory instead of the Arduino uno 32kB.  Its is still a great alternative for small not so code intensive projects.

Along with having a small package, if you run this off battery you want to make sure it’ll last more than a couple of days.  To fix this issue, we can implement a sleep cycle and wake it up using a watchdog timer that’ll make it last for easily over a year on 2 AA NiMh batteries.  Below I’ll add the sleep code you can paste into your own to add a sleep function to your ATTiny85 projects.


  • x1 ATtiny85 – Link
  • x1 Arduino Uno – Link


Below is a general wire diagram for connecting the Arduino Uno and the ATtiny85 in order to upload your program.  Unlike the Atmega328P used on the arduino, the ATtiny85 does not require a special boot loader in order to upload Arduino code.

Blog - ATtiny85_Arduino

Here is a schematic version below:



The next step is to download the libraries for the ATtiny85.

Go to file -> Preferences

Under Additional Boards Manager URLs copy and paste this link:


Then click ok.

Next, go to tools -> Board -> Boards Manager

Board Manager

Next, type in ATtiny85 on the search bar and install the ATTinyCore by Spence Konde.  Select the newest version available.


Now that you have the libraries installed for the ATTiny85 IC, you next need to setup your Arduino uno to be an ISP programmer to upload your code to the ATTiny85.


Once you’ve opened up that example code, you upload that sketch file into your arduino.

Next step is to choose the right board before uploading.

REMEMBER TO SELECT ARDUINO AS ISP UNDER PROGRAMMER or your code will not upload to the Attiny85.


The last step before being able to upload your code to the ATTiny85 is to make sure your settings in the image above are exactly the same.


/// Title: Auto Garden Project (Tiny) //
/// Author: Steven Guzman //
/// Date: 5/11/17 //
/// Description: This code can be added to any ATTiny85 project in order to put it into //
/// a sleep cycle //

#include &lt;avr/sleep.h&gt;
#include &lt;avr/wdt.h&gt;

int watchdog_counter = 0; // Used for looping the watchdog timer

watchdog_counter++; // Increments the watchdog timer counter

void setup()
set_sleep_mode(SLEEP_MODE_PWR_DOWN); // Power down everything, will only wake up from WDT
sleep_enable(); // Enable sleep

void loop()

ADCSRA |= (1&lt;&lt;ADEN); // Turns on ADC in order to read analog values

// 15 = 2 minutes
// 37 = 5 minutes
// 75 = 10 minutes
// 112 = 15 minutes
// 255 = 30 minutes
// Loops the 8 second internal to extend the sleep state

while (watchdog_counter &lt; 15)
ADCSRA &= ~(1<<ADEN); // Turns off the ADC sleep_mode(); } watchdog_counter = 0; } // This is creating the back end code for running the sleep // function of the ATTiny85. The longest sleep cycle is // 8s //From: // 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms // 6=1 sec,7=2 sec, 8=4 sec, 9= 8sec void setup_watchdog(int ii) { byte bb; int ww; if (ii &amp;gt; 9 ) ii=9;
bb=ii < 7;
if (ii > 7) bb|= (1<<5);
bb|= (1<<WDCE);

MCUSR &= ~(1<<WDRF);
// start timed sequence
WDTCR |= (1<<WDCE) | (1<<WDE);
// set new watchdog timeout value
WDTCR = bb;

For some reason the html code doesn’t properly convert the characters, I’ve attached the arduino file here.


Now that you have the code ready. The next thing is to upload your code into the ATTiny85. Simply click on the right arrow in the tool bar and it’ll start uploading.



Hopefully this helped you guys learn how to easily use an ATTiny85 with your Arduino code.  They are a little limited in what they can do but if your project is not that complicated and you need to save space then this is the micro controller for you.

Please leave me any comments below let me know what you think.


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