See Problems

“Failure isn’t fatal, but failure to change might be.” – John Wooden

On June 4, 1942, the Japanese Navy arrived at the island of Midway to battle the United States Navy.  They had twice the number of pilots, planes and firepower.  Clearly with this much difference between these two forces, the Japanese should have won.  But that’s not what happened. In a surprising turn of events that became lore and even feature length movies, the United States won the Battle of Midway and that catastrophic defeat devastated the Japanese Navy.  It led to their inability to wage war in the Pacific for the remainder of the Second World War. 

Dr. Steven Spear from MIT, tells this story and asks the question, “When do you suppose the Japanese lost the Battle of Midway?”  Books have been written on the exact details of each maneuver during the battle to try to determine the exact moment that spelled the loss for Japan.  Prepare for a surprise.  The Battle of Midway was lost in 1929, not 1942.  Over a decade before!  Here’s the deal, by 1929 the Japanese Admiralty had locked in their assumption on how wars would be fought and won on the sea.  Everything was built upon the assumption that the entire fleet of one nation would face the entire fleet of the other head on. That doctrine dictated how they designed their aircraft, their carriers, their procedures and tactics.  They scripted the entire battle plan for Midway and conducted war games to rehearse it.

During the war game they set up a huge table with the layout of the two sides.  The Japanese Admirals sat on one side of the table and brought in junior officers to play the side of the US.  Both sides used sticks to push the wooden ships around the map.  After a few back and forth moves, a referee blew a whistle and accused the junior officer of not playing according to the battle plan.  He was kicked out and another junior officer was recruited.  This officer did the same thing as the former one, he looked down the table, realizing he was significantly outmatched, he too deviated from the battle plan and began to win against the Japanese side.  Once again, he was accused of not understanding the battle plan and dismissed.  This same thing happened until they went through all the junior officers, then petty officers and even brought in noodle vendors off the street.  Each time the US side won and the Japanese Admirals were frustrated that nobody was playing by the battle plan.  Instead of seeing the problem that these exercises were showing, they fixated on pathologically rehearsing their failed plan.  That is how the battle was lost.

The lesson here is powerful.  We often believe we know the best way to solve problems.  We can go to great lengths and details in defining and prescribing the solution.  But if the solution is not tested or we are unwilling to observe and build ways to see problems and learn, we can suffer catastrophic failures similar to the Japanese Admiralty.  We should design and test our systems in such a way that we can clearly detect problems, learn from them and alter course when discovery is made.  Avoiding that is effectively setting a course for failure.

A growth mindset seizes upon unexpected events or failures as golden moments of learning.  I believe this applies to all of life, not just our engineering efforts.  We all make plans, sometimes elaborate plans, and yet how do we react when those plans are thwarted?  Do we dismiss the opponent and try to get back to plan, or do we learn and alter our course?  I know this is a growth area for me.  I often want to push ahead with full force to get something done.  This pandemic has thwarted and change a lot of our plans.  But do we surrender or do we embrace the discovery as new opportunity?  Don’t become discouraged, fatigued or apathetic.  Convert problems into energy and redirect it towards a positive direction.  The secret power of successful businesses, teams and individuals is the ability to quickly learn and adjust to discovery. 

Are you struggling with your own plan failures?  Don’t give up!  Look at those failures as opportunities for learning and adopt the change.  The battle is not lost.  Glean the learning and become better.  You can do this.  Keep learning!

Road Construction Ahead

“We believe that people with passion can change the world for the better… and those people that are crazy enough to think that they CAN change the world, are the ones that actually do.” – Steve Jobs

Road work ahead!  For the past two weeks we have had road construction in our neighborhood.  Like a marching band, the big equipment moved in with all the familiar drumming, scraping, cutting, dumping and rolling sounds.  In the past, I doubt I would have given it much thought as I commuted to and from the train to get to work.  But this time I have the pleasure of soaking it all in.  On our morning walks I get to see it all up close, greeting the workers moving about in some sort of construction choreography, adorned with branded masks and new coronavirus safety rules.  Watching this work, I’m reminded of the incredible value of building and maintaining this vital infrastructure for our society.  Roads, bridges, utilities, vehicles and buildings all create a platform for our communities, country and world to live, connect, conduct business and shape new ideas into reality.  Infrastructure propels us forward. 

I love technology.  Right out of college, my dad convinced me to join his civil engineering firm to help him, as he called it, “computerize the business.”  I didn’t know anything about civil engineering, but leaned into my science background and learned the complexities of land surveying, hydrology, material science, logistics and structural engineering.  I was amazed at the work that was done manually calculating, planning, drawing, erasing and drafting again.  I introduced the staff to AutoCAD and the coordinate geometry tools I had built to help accelerate their work.  But I was about to learn a big lesson in change management. 

“You’re crazy!”  The engineers were adamant that they didn’t want those “darn computers” (and other colorful adjectives) anywhere near their projects.  I couldn’t understand why everyone wouldn’t want to embrace new technology.  Instead of giving up, I pivoted and took on a housing development project myself.  Working with a skeptical but supportive colleague, we loaded all the elevation data to build contour maps and went to work planning streets, utilities, houses and storm systems.  The client loved the initial plans but after a review by the city, a major rework was required to expand the housing lots and add a park.  This is where the magic happened.  In the past, that would have been a start over scenario, but by having the entire project in the computer we only needed to make a few modifications to the model and the entire set of plans were ready to be released for construction.  The skeptics were blown away with the turnaround.  All the initial resistance gave way to aggressive adoption as they all saw how the computer had chewed away the toil, tedium and time to deliver plans. 

Technology amplifies human ability.  We leverage information technology to connect, to accelerate and displace manual steps, to elevate our capabilities and extend our horizon.   As technologists, we have an incredible opportunity to build a better world.  Through our trade, we can construct next generation digital infrastructure, better connect people to people, people to ideas, and ideas to reality. 

Technology builds upon technology.  Prior generations of tools stack to scaffold us up to the next level, which becomes the platform for the next.  Despite the entire world being in time out for COVID-19, people are still working, business is still being conducted, things are still moving forward, because of technology put into place by people like you. 

As technologists, we can make a difference.  Our human family is counting on us to help keep the information roadways maintained and improved.  Our companies are counting on us to use our expertise to power our businesses, to ship value better, faster, safer and happier. 

What crazy ambitious ideas do you have to help change the world?  What can we do to better help each other through technology?  I challenge you this week to give that some thought.  Let’s be some of the crazy ones who want to change the world.  Who knows, we might actually do it!

Digital Scale for 3D Printer Filament

This project is to add a load cell to the filament spool holder of a Creality Ender 3 Pro 3D-printer to measure and display weight of spool. Using the tare function of the scale on an empty spool, the user can determine the amount of filament (in grams) remaining on a spool.

This project uses an Arduino or ATtiny85 microcontroller with the HX711 load cell module for weight measurement and a TM1637 4-digit LED display. Project GitHub Link

Components

  • ATiny85 Microcontroller (DigiKey)
  • TM1637 4 Digit Segment LED Display (Amazon)
  • Load Cell with HX711 Load Cell Amplifier (Amazon)
  • 100uF Electrolytic Capacitor
  • 5V Power Supply – Micro USB to DIP 5-Pin Pinboard (Amazon)

Schematic

Schematic

How to Build

The filament scale mounts on top of the Ender 3 top rail where the filament spool is located. You will need to print the load cell mount and the LED display box. This is available on Thingiverse or Tinkercad. See example build pictures below.

Setup & Calibration

Download the Arduino code here: https://github.com/jasonacox/Ender3-Filament-Digital-Scale

This sketch requires that you calibrate the load cell. This involves the following steps:

  1. Run the sketch with DEBUG true (using a Arduino Uno or other microcontroller with serial)
  2. Record the “HX711 reading” values with NO load on the scale – this is your “CAL_OFFSET
  3. Use an trusted scale and weigh an object (grams or kg) – record this value as your “KNOWN-VALUE
  4. Place the object on the load cell and record the “HX711 reading” – this is “CAL_VALUE
  5. Compute the CAL_RATIO = (CAL_VALUECAL_OFFSET) / KNOWN-VALUE
  6. Edit the #defines in the code
    CAL_OFFSET  = -148550
    KNOWN_VALUE =  382.7186 g
    CAL_VALUE   = -107150
    CAL_RATIO   = (CAL_VALUE - CAL_OFFSET) / KNOWN_VALUE
    CAL_RATIO   = ((-107150) - (-148550 )) / (382.7186)
    CAL_RATIO   = 108.17

Programming Notes

The TARE button uses PB0. If you use the Tiny AVR Programmer from Sparkfun it drives an LED on PB0 and once the sketch is uploaded, the ATTiny will read PB0 as LOW and assume you wish to TARE the scale. You will need to remove the the chip from the programmer after uploading to get it to work correctly in the circuit.

Tare Function

On start the circuit will read the last TARE value from EEPROM and display the the current weight. Press and hold the TARE button and the current weight value will be recorded in EEPROM and subtracted from the current reading to “Zero” out the scale.

Assembly

The 3D model for the case and load cell mount is on Tinkercad and available for download on Thingiverse. The case is open-back for simplicity and it has mounting holes that use the existing spool bolts and fasteners.

I used a small 20mm wide project circuit board to mount the ATtiny85 socket, resistor, electrolytic capacitor and microswitch. The microswitch is located on the bottom and will face the hole on the front of case. A circular 3D printed button will fit in the hole and press against the microswitch to activate the TARE function.

The case is designed to hold a USB plugin board, the TM1637 display, the controller board and the HX711 load cell module. The HX711 slides in with a hole on the side to feed the load cell wires.

You will need M5 bolts to mount the load cell onto the 3D printed case bracket (see pictures below) with bolts going up into the threaded load cell holes. The filament spool holder that came with the Ender 3 Pro will attach to the “load” end of the load cell (the end marked with the down arrow and max weight). A 3D printed shim adapter will go between the filament holder and the load cell. An M4 bolt will go down and tighten into the load cell. The other M4 bolt will need a M4 nut under the shim.

Attach the scale and filament holder back on to the top of the Ender 3 Pro using the two M5 bolts and M5 T-nuts that came with the printer.

Plug in the scale and put an empty filament spool on the holder. Press the TARE button to zero out the weight (it records this TARE value in EEPROM memory so it remembers it on power cycle – you shouldn’t have to use TARE again). Now replace the empty spool with one with filament. It will now show you the estimated amount of filament remaining. it has been surprising accurate for my project. Notice the example below shows a slightly used 1kg spool is reading 992 grams.

Optional Roller Addition

I immediately noticed that when printing, as the extruder stepper pulls the filament, the weight will change, reflecting the dynamic force of the pull and the sliding friction resistance of the static spool holder rod.

I decided to addd a real roller to the spool holder so I printed this model that uses two bearings to remove friction: https://www.thingiverse.com/thing:3209211

References

ATtiny85 Weather Station

Weather Station

This project will show you how to build an ATtiny85 based mini Weather Station that displays temperature, humidity and pressure using four easy to read 7-segment LEDs.

Requirements

This sketch requires a version of the Wire library that is compatible with the ATtiny85 for the I2C communication to work with the BME-280 sensor. I used the ATTinyCore arduino core by Spence Konde which has a version of the Wire library that works with the ATtiny85. I was able to use the standard Adafruit_BME280 library to pull data from the BME-280. You can install ATTinyCore by putting the board manager URL in the Arduino IDE preferences:

http://drazzy.com/package_drazzy.com_index.json

Set the board to the ATtiny85 chip at 1Mhz (internal).

Circuit

Components:

  • ATiny85 Microcontroller (DigiKey)
  • BME-280 Sensor (Temperature, Pressure, Humidity) (Amazon)
  • 74HC595 8-bit Shift Register (Qty 4) (DigiKey)

Sensors

  • 7-Segment LED Display (Qty 4) (DigiKey)
  • 0.1uF Ceramic Capacitor (Qty 2)
  • 100uF Electrolytic Capacitor
  • 5V Power Supply (Alternatively you can use a 5V Solar cell, 3.7V lithium ion battery and a TP4056 constant-current/constant-voltage linear charger to charge the battery during the day).

Schematic

Circuit Board

ATtiny85 Microcontroller

Circuit Board

Programming Notes:

Code for this project is located on Github: https://github.com/jasonacox/ATtiny85-Weather-Station

I2C communication with BME-280 uses pins PB0/SDA and PB2/SCL. If you use the Tiny AVR Programmer from Sparkfun or something similar, keep in mind that it drives an LED on PB0 which will interfere with I2C communication. You will need to remove the chip from the programmer after uploading to get it to work in the circuit.

Memory Warning

This sketch uses nearly all of the ATtiny85 program storage space (8K) so you may get an overflow error if the libraries change or you add any code. To address this, I created a minimized BME280 library to reduce the PROGMEM space required. You will need to download and install the Tiny_BME280_Library library in:

~/Documents/Arduino/libraries/ directory and restart the Arduino IDE.

Display

  [ 70'] - Temperature in degree F 
  [ 24r] - Relative Humidity %
  [_970] - Pressure in hPa with rising/falling animation
  [ 21c] - Temperature in degree C 

Construction

I used two circuit boards: Display and Logic board. The Display board holds the four 7-segment LEDs with the array of resistors. On the back are header pins that plug in to the logic board. The Logic board holds the 4 register chips and the ATtiny85. On the back are headers for the Display board to plug in.

Logic and Display boards: 

Both boards together and running: 

I printed a simple cylinder case (Thingiverse) to mount the weather station and have it on the back patio: 

Power Supply

The circuit will run on 5V or 3.3V. I used an existing solar panel, battery and TP4056 charger circuit to power this project with a 3.3V regulator.

Solar Power Option

  • 1 x 2.5W 5V/500mAh Solar Cell – Amazon
  • 1 x 5V Micro USB 1A TP4056 Lithium Battery Charging Board with Protection Charger Module Amazon
  • 1 x 3.7V 3000mAh 755068 Battery Rechargeable Lithium Polymer ion Battery Pack – Amazon
  • 1 x 3.3V Linear Regulator 250MA MCP1700-3302E/TO – DigiKey

ATtiny85 Ultrasonic Distance Measurement for Parking Help

After discovering the tiny but mighty ATtiny85 microcontroller, I decided to put it to use to help me park my car in the garage. Sure, I could continue to use the softball hung from the ceiling to let me know when I have the car pulled in far enough, but why not take advantage of some tech and have it show me instead? Alternatively, for these times, it is also a fun way to clearly demonstrate 6ft social distancing. 😉

ATiny85 Microcontroller

The ATtiny85 has 5 GPIO easily usable pins (technically you can even use Reset pin as a 6th GPIO but that makes it much more difficulty to reprogram). For information about how to program the ATtiny85, see my previous blog post here.

The tiny but mighty ATtiny85 Microcontroller Pinout

For my “Parking Helper” project I decided to use the low cost entry level ultrasonic distance sensor, the HC-SR04 and two 7-Segment LEDs to show the distance between the device and the front of the car.

HC-SR04 Ultrasonic Sensor

The HC-SR04 has 4 pins: VCC, Trig, Echo and Gnd. The Trig and Echo lines will be driven by the Attiny85.

HC-SR04 Ultrasonic Distance Sensor

The HC-SR04 measures distances by sending (TRIG) an sound pulse and measuring the time it takes for the ECHO. Sound travels through air at 332 meters per second at 20 °C (68 °F). Using this the unit provides a duration pulse back to the controller that can be used to determine the distance.

The speed of sound is: 343m/s = 0.0343 cm/uS = 1/29.1 cm/uS

I found a great project here where the author uses the HC-SR04 as an ultrasonic rule. Using the ATtiny85 to trigger and receive the duration pulse we can determine the distance to the parked car.

// Send TRIG HIGH for 10 microseconds 
// to trigger the HC-SR04 to send a sound pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

// Read the ECHO duration
  duration = pulseIn(echoPin, HIGH);

// convert the duration to cm
  distance = (duration / 2) / 29.1; 

LED Display (2 Segment)

Driving the display with two 7-segment LEDs is a bit more complicated. Each segment has 7 LEDs to form the numbers plus one LED for the decimal point. That would require 8 GPIO ports for each LED Display or a total of 16 GPIOs! The ATtiny85 has only 5 available for use so we need another way. Thankfully, we can use two low cost 8-bit shift registers (74HC585) and get by with using only 3 GPIO and still drive the 16 LEDs on the two displays.

74HC595 8-bit Shift Register to Drive 7-Segment LED Display

Here is how it works… The ATtiny85 sends the binary data for the the numbers to a first 74HC595 8-bit register using its “Data Input,” “Clock” and “Latch” lines. Once the register receives a total of 8 bits (1 byte), it will overflow the data out through its “Output” line which can be connected to the “Data Input” of another register.

We toggle the “Clock” to signal to the registers to record the value of the data line (1 or 0). We do that for each of the bits of the two bytes we need sent for each display. Finally, we have the ATtiny85 toggle the “Latch” to let the registers know when the transmission is complete. They then lock the 8 output lines (QA to QH) to high or low depending on what they recorded. These lines are connected to the individual LEDs on the 7-segment LED displays.

I found a great example of using the 74HC595 to drive multiple LED Displays here. I used that code to send the data as well as the byte arrays used to form the numbers on the LEDs. Since that project was using a common anode LED and my project uses a common cathode LED I had to flip the bits. In the code below, a one (1) value would drive the LED high (on) and a zero (0) would drive it low (off).

/* Set up 7-segment LED Binary Data

     |--A--|
     F     B
     |--G--|
     E     C
     |--D--|   H - Decimal

     0b00000000
       ABCDEFGH
  */  
  numArray[0] = 0b11111100; // 0 - Zero
  numArray[1] = 0b01100000; // 1 - One
  numArray[2] = 0b11011010; // 2 - Two
  numArray[3] = 0b11110010; // 3 - Three
  numArray[4] = 0b01100110; // 4 - Four
  numArray[5] = 0b10110110; // 5 - Five
  numArray[6] = 0b10111110; // 6 - Six
  numArray[7] = 0b11100000; // 7 - Seven
  numArray[8] = 0b11111110; // 8 - Eight
  numArray[9] = 0b11110110; // 9 - Nine
  numArray[10]= 0b00000000; // All Off

Circuit Schematic

Pulling it all together, here is a schematic I put together that combines the ATtiny85 with the two 74HC595 registers, two LED displays and the HC-SR04 ultrasonic sensor.

A Kicad schematic is included in this project and the schematic export is sown above. The circuit is powered with a steady 5V DC supply (e.g. USB adapter). The HC-SR04 is an entry level sensor and does suffer from some fluctuation. Logic in the code attempts to stabilize the measurement by making multiple readings.

List of Materials

  • 1 x ATiny85 Microcontroller (DigiKey)
  • 2 x 74HC595 8-bit Shift Register (DigiKey)
  • 1 x HC-SR04 Ultrasonic Distance Sensor (DigiKey)
  • 2 x 7-Segement LED Display CC (DigiKey)
  • 16 x 220 Ohm Resistor
  • 1 x 100uF Electrolytic Capacitor (DigiKey)
  • 1 x 0.1uF Ceramic Capactior – (Amazon)

Code

The code for the project can be found on GitHub: https://github.com/jasonacox/UltrasonicDistanceDisplay

Imperial and SI Units

In Imperial unit mode, the code is written to display distances in inches (1 to 11) for distances less than 1 foot. Once the distance reaches 1 foot, it will show feet in decimal (1.0 to 9.9) until the distance reaches 10 feet when it will display in feet only (e.g. 10).

In SI unit mode, it will show centimeters for distances less than 1 meter (1 to 99, then it will show meters with decimal (1.0 to 9.9) until the distance reaches 10 meters and will continue to show meters only.

To toggle Units: Hold the distance to 4 (either unit) for ~4 seconds and it will toggle between units. Imperial mode will flash “in” and SI mode will flash “c”.

Sleep Feature

Sleep Mode: The code includes logic to turn off the display when there is no movement and power back on when movement is detected.

Prototype

Prototype Model without Box

ATtiny85 Arduino Programming with Sparkfun Tiny Programmer on a Mac

This guide will help set up a Mac OS computer to program an ATtiny 85 using the USB Tiny AVR Programmer from Sparkfun and the Arduino IDE.

Required Items:

  • Sparkfun Tiny AVR Programmer (Sparkfun) – This is a handy USB based programmer for ATtiny microcontrollers. It is powered by an ATtiny84 that is set up as a USBtinyISP programmer. The board has an 8 pin socket to hold a ATtiny45/85 microcontroller that you want to program.
  • ATtiny 85 Microcontroller (Digikey) – The ATtiny85 is a low-power 8-bit microcontroller based on the AVR enhanced RISC architecture.
  • Arduino IDE 1.8.12 (Download)
  • Mac computer (e.g. MacBook Pro) with OS 10.14 or later

I used the following steps to get the Sparkfun Tiny AVR Programmer working on my Mac. Hopefully this will be helpful for you as well. Your experience may vary.

Step 1: Install ATtiny85

Install the ATtiny 85 into the programmer. Make sure you orient the chip so that pin 1 (usually identified by a dot) is by the notch. Once this is installed, plug the USB into your computer. You will not see a light and Mac OS will not recognize it as a serial port (don’t worry).

Install ATtiny into Programmer

Step 2: Set up Arduino IDE

Install the Arduino IDE software (Download) and navigate the menu Arduino -> Preferences and in the field for “Additional Board Manager URL” paste this link:

https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json

Click “OK” to save and restart the Arduino IDE. Navigate the menu Tools -> Board -> Boards Manger and type “attiny” into the top search board and there will click on the “Install” button on the attiny board package.

Find the attiny board package and Install.

You should now see an entry for ATtiny in the Tools > Board menu. Select “ATtiny25/45/85”.

For “Processor” select the chip you are using, e.g. ATiny85.
For “Programmer” select “USBtinyISP

Please note: On the Mac, you do NOT select a serial “Port”. The IDE will program the ATtiny through the USBtinyISP that is loaded on the Tiny AVR Programmer board.

Step 3: Program your ATtiny85

You can use the example blink test to make sure you can program your ATtiny85. You can use the built in blink test but you will need to change the LED_BUILTIN to be 0 (zero). You can also copy and past the following code:

void setup() {
  pinMode(0, OUTPUT);
}

void loop() {
  digitalWrite(0, HIGH);   
  delay(1000);                       
  digitalWrite(0, LOW); 
  delay(1000); 
}

Click the upload button (right arrow) and the built-in LED should start to flash.

Example “blink” program running on ATtiny85

The ATtiny85 has PWM (Pulse Width Modulation) outputs so you can use the analogWrite() function to adjust the brightness of the LED from 0 to 255. Here is an example that fades the LED.

/*
  Fade

  This example shows how to fade an LED on using the analogWrite()
  function.

  The analogWrite() function uses PWM, so if you want to change the pin you're
  using, be sure to use another PWM capable pin. On most Arduino, the PWM pins
  are identified with a "~" sign, like ~3, ~5, ~6, ~9, ~10 and ~11.

*/

int led = 0;           // the PWM pin the LED is attached to
int brightness = 0;    // how bright the LED is
int fadeAmount = 1;    // how many points to fade the LED by

void setup() {
  pinMode(led, OUTPUT);
}

void loop() {
  analogWrite(led, brightness);

  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade:
  if (brightness <= 0) {
     analogWrite(led, 0);   
     delay(1500);
     fadeAmount = -fadeAmount;
  }
  if(brightness >= 255) {
    fadeAmount = -fadeAmount;
  }

  delay(10);
}

References

Solar Powered WiFi Weather Station

I’ve always wanted to add a backyard weather station to help record not just temperature data, but humidity, pressure, rainfall, wind speed and UV levels. My recent experiments introduced me to the ESP8266 NodeMCU, a low-cost microcontroller with embedded WiFi. I just needed to add a solar cell, a battery, a sensor and an enclosure.

Solar Power

I found a 2.5W 5V/500mAh solar cell (from Amazon) and a 3.7V 3000mAh rechargeable Li-ion battery pack (Amazon). After some research (see here), I added a TP4056 charger module (Amazon) that regulates the charging and protects the battery from overcharge.

Solar cell and battery charging circuit.
Solar Cell + Battery Power Supply

I added a 0.1uF ceramic capacitor and 100uF electrolytic capacitor to smooth the output voltage. I used a simple 3.3v voltage regulator (DigiKey) to feed the 3.3v bus for the ESP8266 and sensors.

Voltage Divider
Voltage Divider

Monitoring the voltage coming from the solar cell and/or battery would help determine if the system is getting enough power during the day to keep the system running at night. The ESP8266 has an analog input (A0) that can be used to determine the output voltage but it can only handle up to 3.3v. By using a simple 2 resistor divider circuit (see right) I could monitor the voltage and apply a multiplier to get to the actual voltage I measured with a multimeter. In this case, the A0 pin was reporting 907 when the multimeter was showing 4.69v so I used 4.69 / 907.0 and further sampled other readings to ensure I had the correct value.

Voltage Charge and Discharge over 4 Days

Circuit Design

The sensors I wanted to add included a BME280 pressure and humidity sensor, a one-wire DS18B20 temperature sensor and a 2N2222 transistor powered rain detector. I put the circuit together using a simple breadboard and started on the code.

Prototype Solar Power Weather Station
Prototype Solar Power Weather Station

Using the free open source KiCad electronic design software, I build a schematic drawing to help build the final non-breadboarded product.

Schematic - ESP8266 Solar Powered Weather Station
Schematic – ESP8266 Solar Powered Weather Station

Getting Started with Arduino IDE and ESP8266

The ESP8266 NodeMCU has a USB port that allows the microcontroller to be easily powered and programmed with the Arduino IDE . However, it is not as easy to set up and use as an Arduino device. I found out that you will need to install a driver to see the device on my MacBook (see here for MacOS instructions and download the USB to UART Bridge VCP Drivers here). Once the driver is installed, the Arduino IDE needs to be set up to manage the NodeMCU. The ESP8266 I purchased came with some instructions:

Instruction & Steps of How to use:
1. Download and Install the Arduino IDE (download here)
2. Set up your Arduino IDE as: Go to File->Preferences and copy the URL below to get the ESP board manager extensions: http://arduino.esp8266.com/stable/package_esp8266com_index.json
3. Go to Tools > Board > Board Manager> Type “esp8266” and download the Community esp8266 and install.
4. Set up your chip as:
Tools -> Board -> NodeMCU 1.0 (ESP-12E Module)
Tools -> Flash Size -> 4M (3M SPIFFS)
Tools -> CPU Frequency -> 80 Mhz
Tools -> Upload Speed -> 921600
Tools -> Port -> (whatever it is)
5. In Arduino IDE, look for the old fashioned Blink program. Load, compile and upload. Go to FILE> EXAMPLES> ESP8266> BLINK

Code

Once I had the ESP8266 connected, I could start creating the code. The code is available here: https://github.com/jasonacox/WeatherStationWiFi

Rain Sensor

Using a simple NPN transistor, you can detect the presence of water. I wanted to detect rain which mean that I needed to add a couple of electrodes connected to that transistor (for detection) and our power supply. Water allows a small amount of current to pass through it to detect water, you will need to amplify it, hence the need for the transistor which turns a low current into a switch to a much larger current. The ESP8266 digital inputs can see the switched power from the transistor and can indicate water has been detected.

Wind Speed Sensor with an Anemometer

An anemometer is a device used to catch the wind and record its speed.

3D Printer

I found a 3D model on https://www.thingiverse.com/thing:2559929

More to come…

Installation

The Unicorn Project

The Unicorn Project: A Novel about Developers, Digital Disruption, and Thriving in the Age of Digital, by Gene Kim

This new novel by Gene Kim takes place simultaneously as the events of The Phoenix Project with many of the same characters, business challenges and end results. All of this continues to take place within the fictional company, Parts Unlimited. However, while the prior book gave us insight into the transformation of the operations team, this book chronicles the journey from a developers point of view.

The Unicorn Project takes you on a fun and inspiring journey into some of the most difficult IT and business challenges we face today.  The project may be mythical, but the lessons and ideals uncovered here provide real help and inspiration to any leader seeking to transform their business. Along the way, you discover people empowering, data driven and digital business enabling ways of working that can unleash the powerful potential within any organization. 

There are five ideals that are discovered through the course of the book that will help any business succeed.

  • The First Ideal – Locality and Simplicity
  • The Second Ideal – Focus, Flow, and Joy
  • The Third Ideal – Improvement of Daily Work
  • The Fourth Ideal – Psychological Safety
  • The Fifth Ideal – Focus on our Customer

I recommend this book for any business or technology student, professional or leader who is serious about leveraging data driven digital disruption and workforce empowerment to delivering business value faster, better, safer and happier.

More information about the Unicorn Project.

Home Automation – SentryPi

Who left the garage door open?

We have a full house with a lot of activity and visitors.  There have been several times when the garage door is left open for extended periods of time.  While our Christmas decorations and paint supplies may not be a treasure most would be thieves would desire, it is still not the most comforting thing to think about leaving the garage open for all passerby to see.  I often thought it would be great to have a way to notify whoever is in the house that the garage is open.

Phase 1 – LED Indicator

I decided that my first step would be to design a way to detect “door open” by providing a simple indicator light.  I explored a few optical ways to do this (light beam, camera, reflectors) but quickly pivoted my approach when I found some unused microswitches.

I found a good place to detect “closed” on the main track.  I thought about piggybacking on the garage opener sensors but dismissed that as I didn’t want to risk an undesirable interaction with the opener and more importantly, I wanted to have the detection work even if power to the opener was interrupted.

This required that I build a bracket to mount the switch to and a ramp plate to compress the switch when the door was in the down position.

I used an aluminum sheet, cut with sheet metal snips,  bent and drilled holes to mount the microswitch and eventually attach it to the garage door track.  It took a few tries to get the right fit and right placement of the micro switch.

My first attempt destroyed the microswitch after a few uses.  The garage door track sled has a straight edge that collides with the microswitch roller. It created too much force on the small roller and eventually popped it loose.  To help with that, I added an aluminum ramp to the sled so that the microswitch roller would gently rise as the sled entered the “closed” position.

I decided to make the “door open” state be the closed circuit condition so that phase 1 of the project could start as a simple LED circuit indicator.

I attached the switch and drilled some pilot holes and mounted the bracket to the garage door track right above the sled when the door is in the closed position.

I added a 9V battery, a 470 ohm resister and a red LED to the circuit.  To complete this phase, I ran the wire from the garage to our entry hall and mounted an LED and housing above the HVAC controls.  Now we can all see the brilliant red LED glowing when the garage door is open.  That covers some of our use cases but I also want a more proactive notification.  Now on to phase 2…

Phase 2 – Raspberry Pi – Home Automation Sentry

Now that I have a working “door closed” sensor and indicator, I am ready to add the proactive home automation component, specifically the Raspberry Pi (RPI).  It just so happens that I have a spare RPI Model 3 that needed a project, and I wanted to experiment with AWS IoT services.

Raspberry Pi 3 B

I used the RPI to detect the state of the switch. To do that, I will need to wire the circuit into the RPI’sGPIO headers.  I decided to use GPIO Pin 23 and the adjacent ground (GND) pin.

Here is the code that is used to detect the closed circuit (indicating an open door):

#!/usr/bin/python

##  
## Garage Door Sentry - RPI script to monitor door
##  

## load libraries
import RPi.GPIO as io 
import time 

print "Garage Door Sentry\n\n"

## set GPIO mode to BCM - allows us to use GPIO number instead of pin number
io.setmode(io.BCM)

## set GPIO pin to use

door_pin = 23
print "Sentry Activated - Watching: GPIO 23"

## use the built-in "pull-up" resistor
io.setup(door_pin, io.IN, pull_up_down=io.PUD_UP)  # activate input

## States for door: 0=closed, 1=open, 2=init
door=2
## infinite loop
while True:
    ## if switch is open
    if (io.input(door_pin)==True and door!=0):
        door=0 
        print "Door closed"
        # do some action
    ## if switch is closed 
    if (io.input(door_pin)==False and door!=1):
        door=1 
        print "Door open"
        # do some action
    time.sleep(1) # 1 second wait

The next step was to connect to AWS IoT to record this sensor data and send alert messages to my phone.

The following will help you set up your Raspbery Pi as a platform to install the SentryPi scripts.

Required:

  • Raspberry Pi – B+, 2 or 3
  • Wifi Dongle or Network Cable configured
  • SD card (Recommend: 16GB or larger)
  • AWS Account (IoT, DynamoDB)

Read the details on this GitHub Project: https://github.com/jasonacox/SentryPi

The project describes how I added these additional features:

  • Sentry Alert – Send a text message to contacts when an alert condition is reached.
  • Dashboard – Provide an automation dashboard for realtime status.
  • Other Sensor Data:
    • Temperature Sensors
    • Barometric Pressure Sensor
    • Humidity Sensor
    • Motion Sensor

To set up a web based dashboard, I decide to use static HTML, CSS and JS (jQuery, Chart.js and the AWS JavaScript SDK) so it can be hosted on a simple S3 bucket, a web server, or the RPi itself.  See here for the code. 
SentryPi Dashboard
SentryPi Dashboard - Garage Door Graph

DevOps Enterprise Summit – London 2017

#DOES17

I had the privilege of attending and speaking again at this years DevOps Enterprise Summit in London at Queen Elizabeth II Centre across the street from Westminster Abby and Big Ben. The conference was attended by nearly 700 transformative leaders from companies and organization across the UK and the rest of Europe:  Hiscox, ITV, Barclays, Hearst, Jaguar Land Rover, Lloyds Banking Group, Orange, Northrop Grumman, easyJet, Capital One, UK Ministry of Justice, ING, Swisscom, Lockheed Martin and more.

The speakers’ slide decks and videos of their talks are available now!

Great talk by Chris Hill (Jaguar Land Rover) and a great quote…

I love this quote from Suzette Johnson (Northrop Grumman) – an example of a good leader empowering the team:

Jonathan Smart (Barclays) had several great points, including this courageous quote on challenges along the journey:

I love this quote from Jonathan Fletcher’s (Hiscox) talk:

Creating Digital Magic

I was honored to speak again and talk about our DevOps journey at Disney.

Even though I wasn’t able to record my presentation, TheNewStack provided a great write-up of my talk: https://thenewstack.io/magic-behind-disney-devops-experience/

Ask the Speakers

Great “Ask the Speakers” session with my new friends Jonathan Smart (Barclays) and Andrea Hirzle-Yager (Allianz Deutchland AG):

And…

The best part of this years trip to London?  Yes, an amazing journey through time and space with my sweetie…