Nuts and Volts - February 2018

THE DESIGN CYCLE n BY FRED EADY

Smartphone App Programming

for Remote Control

T

here’s almost nothing you can’t do with a smartphone. However, if you want to cook up something special for yourself using your iPhone or Android device, it’s advantageous to have tools that help you get your arms around smartphone app programming.

You don’t know it yet, but if you can think and code in the Basic and/or C language, you actually have a firm grasp on smartphone app programming. In this installment of Design Cycle, we’ll code an iOS app that can be run on an iPhone or iPad. Using the same coding paradigm, we’ll code the other side of our app to target an inexpensive WEMOS device based on the ESP8266.

Coding the Remote Device

Sub Process_Globals
 Public Serial1 As Serial
 Private server As WiFiServerSocket
 Private wemosPins As D1Pins
 Private;espWifi;As;ESP8266WiFi
 Private astream As AsyncStreams
 Private switch0 As Pin
 Private switch1 As Pin
 Private;switch2;As;Pin
 Private switch0State As Boolean
 Private switch1State As Boolean
 Private;switch2State;As;Boolean
 Private ser As B4RSerializator
 End;Sub

The WEMOS D1 Mini posing in Photo 1 is based on the ESP8266. Since the ESP8266 is involved, that implies communications between the remote Mini and our iPhone will flow over Wi-Fi. The WEMOS Mini can be programmed in many ways. We’ll take the B4R programming path.

B4R is a free programming platform that is geared towards the Arduino. B4R also has a special place in its heart for the ESP8266. Our goal is to code the D1 Mini as a remotely controlled Wi-Fi node. The code we’ll write will toggle the Mini’s output pins. Using the logic levels available at its I/O pins, you can drive relays, LEDs, etc.

We won’t get deep into the inner workings of each line of B4R code as you can easily go to the B4R website and look up any mnemonics you don’t readily understand. You’ll find that B4R source code is self-documenting and easy to follow.