Saturday, May 28, 2016

Control AC devices with a Smartphone

I found this tutorial and thought it was a cool idea. It describes how to control a light (or any AC device) from a Bluetooth app on a smartphone.

I thought it would be something that my granddaughter would enjoy when she comes this summer. The tutorial gives what I assume is a lot of useful information, but it gets into the weeds of bluetooth much more than I'm interested in at this point, and all I want is to allow a 6-year-old to turn a light on and off.

I followed the tutorial though steps 1 and 2.  Step one uses Blink to flash an LED. Step two adds a button with some interrupt handling. The authors do not mention that in order to get this code to work without a bluetooth nRF8001 module connected, you need to comment out the line "blePeripheral.begin();" in setup--otherwise it hangs there--I guess waiting for a bluetooth board. So I got steps 1 and 2 working.

For step 3, I need to add a board. I have the +Adafruit Industries Bluetooth LE module  (nRF8001 chip) that the authors suggest, but I found it simpler to use the Adafruit Feather Bluefruit LE board (nRF51822 chip) . Since the boards use different Nordic chips, I had to figure out how to get the code to work. The Make tutorial uses the BLEPeripheral library, which I did not get to work, so I used the Adafruit_BluefruitLE_nRF51 library, and the functions are very different.

The code in the Make tutorial looked overly complex for what I wanted,  Since this is my first Bluetooth project, so I wanted to start slowly.  Following the Adafruit tutorial, I installed the " Adafruit_BluefruitLE_nRF51" library and the Adafruit BLE connect app for Android and started working through the example programs. "bleuart_cmdmode" did what I needed: communicate between the module and the app. I set it up so that sending "ON"--all caps--turns the light on and "OFF"--caps again--turns it off,

With nothing but the Feather, a resistor, and an LED I was able to turn the LED on and off from my phone. After 40 years of programming I still get a kick out of seeing something work the first time--no matter how simple.

Next I needed to add the PowerSwitch Tail. It was very simple, except that I did not have a screwdriver small enough to tighten the terminal blocks. Fortunately, my brother-in-law has tools (in addition to skills) and we got it connected. I connected pin 1 to the 3.3V rail on the breadboard, pin 2 to pin 6 on the Feather (the LED pin), and pin 3 to the ground rail on the breadboard.  Then I plugged one end of the PowerSwitch to a 110VAC wall receptacle and plugged a light into the other end.

Power Switch Tail with jumper wires, ready for hookup
The PowerSwitch is a Normally Open relay, so when you hook it up the device (light in my case) is off.  When pin 2 on the PowerSwitch is set LOW, the relay closes and the device turns on.  This is the reverse of the way my code worked, so when the LED was on (Feather pin 6 HIGH), the light was off and vice versa.  This makes a little sense--it gives you some light when the AC light is off, but it's not intuitive for a 6-year-old to say "ON"and turn a light off.  So, I added a pin (5), connected pin 2 of the PowerSwitch to that, and set it LOW for ON and HIGH for OFF.

Project Video.

Now that I feel comfortable with the concepts (as far as I've gone), I can go back to the original Make tutorial and learn more. This is cool.

Here's the code that goes with the video (as mentioned above it's a modification of the "bleuart_cmdmode" example in the Adafruit Bluefruit nRF51 library):

 This is an example for our nRF51822 based Bluefruit LE modules

 Pick one up today in the adafruit shop!

 Adafruit invests time and resources providing this open source code,
 please support Adafruit and open-source hardware by purchasing
 products from Adafruit!

 MIT license, check LICENSE for more information
 All text above, and the splash screen below must be included in
 any redistribution

#if not defined (_VARIANT_ARDUINO_DUE_X_) && not defined (_VARIANT_ARDUINO_ZERO_)

#include "Adafruit_BLE.h"
#include "Adafruit_BluefruitLE_SPI.h"
#include "Adafruit_BluefruitLE_UART.h"

#include "BluefruitConfig.h"


    FACTORYRESET_ENABLE       Perform a factory reset when running this sketch
                              Enabling this will put your Bluefruit LE module
                              in a 'known good' state and clear any config
                              data set in previous sketches or projects, so
                              running this at least once is a good idea.
                              When deploying your project, however, you will
                              want to disable factory reset by setting this
                              value to 0.  If you are making changes to your
                              Bluefruit LE device via AT commands, and those
                              changes aren't persisting across resets, this
                              is the reason why.  Factory reset will erase
                              the non-volatile memory where config data is
                              stored, setting it back to factory default
                              Some sketches that require you to bond to a
                              central device (HID mouse, keyboard, etc.)
                              won't work at all with this feature enabled
                              since the factory reset will clear all of the
                              bonding data stored on the chip, meaning the
                              central device won't be able to reconnect.
    MINIMUM_FIRMWARE_VERSION  Minimum firmware version to have some new features
    MODE_LED_BEHAVIOUR        LED activity, valid options are
                              "DISABLE" or "MODE" or "BLEUART" or
                              "HWUART"  or "SPI"  or "MANUAL"
    #define FACTORYRESET_ENABLE         1
    #define MINIMUM_FIRMWARE_VERSION    "0.6.6"
//    #define MODE_LED_BEHAVIOUR          "MODE"
    #define MODE_LED_BEHAVIOUR          "MANUAL" //2016-05-27 vm
    #define TAIL_PIN                    5
    #define LED_PIN                     6
    int LED_STATE;
    char* x;
    char y;

// Create the bluefruit object, either software serial...uncomment these lines
SoftwareSerial bluefruitSS = SoftwareSerial(BLUEFRUIT_SWUART_TXD_PIN, BLUEFRUIT_SWUART_RXD_PIN);

Adafruit_BluefruitLE_UART ble(bluefruitSS, BLUEFRUIT_UART_MODE_PIN,

/* ...or hardware serial, which does not need the RTS/CTS pins. Uncomment this line */
// Adafruit_BluefruitLE_UART ble(Serial1, BLUEFRUIT_UART_MODE_PIN);

/* ...hardware SPI, using SCK/MOSI/MISO hardware SPI pins and then user selected CS/IRQ/RST */

/* SPI, using SCK/MOSI/MISO user-defined SPI pins and then user selected CS/IRQ/RST */
//                             BLUEFRUIT_SPI_MOSI, BLUEFRUIT_SPI_CS,
//                             BLUEFRUIT_SPI_IRQ, BLUEFRUIT_SPI_RST);

// A small helper
void error(const __FlashStringHelper*err) {
  while (1);

    @brief  Sets up the HW an the BLE module (this function is called
            automatically on startup)
void setup(void)
//2016-05-27 define light pins as output and set them to off
//(relay on switch tail is reverse--flops closed for on when low)
  pinMode(LED_PIN, OUTPUT);
  pinMode(TAIL_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  digitalWrite(TAIL_PIN, HIGH);
  LED_STATE = 0;
//  while (!Serial);  // required for Flora & Micro--2016-05-28 vm causes feather to hang if not
//  connected via usb
//2016-05-27 end

  Serial.println(F("Adafruit Bluefruit Command Mode Example"));

  /* Initialise the module */
  Serial.print(F("Initialising the Bluefruit LE module: "));

  if ( !ble.begin(VERBOSE_MODE) )
    error(F("Couldn't find Bluefruit, make sure it's in CoMmanD mode & check wiring?"));
  Serial.println( F("OK!") );

    /* Perform a factory reset to make sure everything is in a known state */
    Serial.println(F("Performing a factory reset: "));
    if ( ! ble.factoryReset() ){
      error(F("Couldn't factory reset"));

  /* Disable command echo from Bluefruit */

  Serial.println("Requesting Bluefruit info:");
  /* Print Bluefruit information */;

  Serial.println(F("Please use Adafruit Bluefruit LE app to connect in UART mode"));
  Serial.println(F("Then Enter characters to send to Bluefruit"));

  ble.verbose(false);  // debug info is a little annoying after this point!

  /* Wait for connection */
  while (! ble.isConnected()) {
  // LED Activity command is only supported from 0.6.6
//  if ( ble.isVersionAtLeast(MINIMUM_FIRMWARE_VERSION) )
//  {
    // Change Mode LED Activity
    Serial.println(F("Change LED activity to " MODE_LED_BEHAVIOUR));
    ble.sendCommandCheckOK("AT+HWModeLED=" MODE_LED_BEHAVIOUR);
//  }

    @brief  Constantly poll for new command or response data
void loop(void)
  // Check for user input
  char inputs[BUFSIZE+1];

  if ( getUserInput(inputs, BUFSIZE) )
    // Send characters to Bluefruit
    Serial.print("[Send] ");


    // check response stastus
    if (! ble.waitForOK() ) {
      Serial.println(F("Failed to send?"));

  // Check for incoming characters from Bluefruit
  if (strcmp(ble.buffer, "OK") == 0) {
    // no data
  // Some data was found, its in the buffer
  Serial.print(F("[Recv] ")); Serial.println(ble.buffer);
//2016-05-27 vm test buffer for ON or OFF, display results  on serial monitor and bluetooth device,
//turn LED and Light on or off (or do nothing)
  if (strcmp(ble.buffer,"ON")== 0) {
      Serial.println("Light ON");
      ble.println("Light ON");
      digitalWrite(LED_PIN, HIGH);
      digitalWrite(TAIL_PIN, LOW); //relay logic is reverse of LED
  } else if (strcmp(ble.buffer,"OFF")== 0) {
      Serial.println("Light OFF");
      ble.println("Light OFF");
      digitalWrite(LED_PIN, LOW);
      digitalWrite(TAIL_PIN, HIGH);    //relay logic is reverse of LED
  } else {
      Serial.println("Light not changed");
      ble.println("Light not changed");

    @brief  Checks for user input (via the Serial Monitor)
bool getUserInput(char buffer[], uint8_t maxSize)
  // timeout in 100 milliseconds
  TimeoutTimer timeout(100);

  memset(buffer, 0, maxSize);
  while( (!Serial.available()) && !timeout.expired() ) { delay(1); }

  if ( timeout.expired() ) return false;

  uint8_t count=0;
    count += Serial.readBytes(buffer+count, maxSize);
  } while( (count < maxSize) && (Serial.available()) );

  return true;