Nuts and Volts - September 2017

The LCD/keypad shield did not come with a pinout for the top side breakout pins. Some of the pins are labeled and some are not.

Figure 1 shows the digital I/O pins and some of the power pins available on the LCD/keypad shield. I/O pins 11, 12, and 13 are not needed with my hardware, but they are available for use if you choose different hardware or add additional control features. I soldered pins into the shield for Reset, Vin, and Ground on the bottom edge of the shield (next to the reset pushbutton), and I connected the ESP8266 and X- 10 interface through pins on the shield.

The menu to set up the timer features is entered by pressing the UP button. All of the parameters except clock time are stored in the Arduino Uno program memory using EEPROM write commands, so they will be remembered during loss of power. The clock time is stored in the DS3231 ATC24C32 RTC. If you use the Set Clock features available in the Setup function of my sketch, it will store year, month, day, hours, minutes, and seconds in the RTC.

There are many resources available through the Internet to program the RTC that you can select if you choose not to use what I provided in the Arduino Uno sketch. A detailed flow chart of the menu system is provided in the Software resources available for download

1. Set Zone 1 ON time.

2. Set Zone 1 OFF time.

3. Set Wi-Fi switches that are active and assign Zone for control.

4. Set Zone 2 ON time. 5. Set Zone 2 OFF time. 6. Set Clock.

The hardware and all software (sketches for the Arduino Uno, ESP8266-01 Wi-Fi module, Itead S20 and Sonoff) utilized in this project are provided at the article link.

How Should I Package My Timer Project?

I wanted a case that had space inside to mount all the electronic components. Most of the cases I found were only large enough for the Uno and LCD shield. My design includes three satellite boards (RTC, ESP8266, and Firecracker), and I wanted space for these components inside my case also. I found a

3D file download; refer to Figure 2. The 3D files are available at www.thingiverse.com/thing:142282.

This presented an additional challenge of having the case printed, but I knew there were many places that would 3D print items these days. Unfortunately, many of the 3D print services I contacted wanted in excess of $100 to print this case. I then discovered that local libraries and universities had 3D printing services and charge by the ounce for the plastic used. This turned out to be a very reasonable approach, and the total print cost was less than $10.

If you take this approach, be prepared to spend a significant amount of time sanding the printed case to give it a professional look. It also took several hours to file the holes in the case for the included 3D printed buttons, and tweaking the bottom of the button height so the buttons interfaced with the pushbuttons on the

LCD/keypad shield. In addition, I had to remove plastic on three sides of each pushbutton so they would flex when pushed.

Helpful Tips for Programming

All modules can be programmed using the Arduino IDE (integrated development environment). To do so, you must install the ESP8266 board manager files into the Arduino IDE. SparkFun has published a helpful installation tutorial at https://learn.sparkfun.com/tutorials/esp8266.../installing- the-esp8266-arduino-addon. In addition, you must install the libraries necessary for my programs into the Arduino IDE. The Resources sidebar in Part 1 includes links to the add-on libraries available at GitHub.com; the Arduino company supported libraries are available for installation using the Library manager inside the Arduino IDE.