To make best use of my effort, I tried to think of something helpful to construct. My younger daughter, who had entered first grade, often forgot to give me letters and handouts from school.

I had gone through the same problem with my older daughter. I was determined not to repeat the same unfortunate cycle of angry mother and crying daughter, so I set about using GR-SAKURA to create a gadget to help my younger daughter enjoy giving me handouts she had brought home from school.

To ensure that my daughter would actual deliver the school notices she brought home, I decided to create a gadget producing a fun reward — involving movement and sound — when a handout was inserted into the slot.

I used a simple mechanism to design the gadget so that when it sensed that a piece of paper had been deposited, the servomotor would be activated to produce a sound. I was hoping to keep it basic enough so that my older daughter (aged 10) would understand the mechanism as well.

I used an optical sensor (CdS sensor) as my detection mechanism; when a letter was deposited, the sensor would detect darkness and recognize that a threshold had been reached.

As far as the sound was concerned, I knew that today’s kids would never be satisfied with a mere beep. Since the GR-SAKURA came with SD capability, I recorded both music and a voice message, and programmed it to the SD. Actually, I recorded my older daughter playing the piano and my younger daughter (the daughter with the school note issue!) saying a message. I involved both daughters in the production process, including them from the stage likely to provide maximum enjoyment and interest on their part.

The thing is, I discovered that I was actually not aware when a letter had been deposited… That called for an additional “mail notification” mechanism to counter overlooked or forgotten mail. We installed a new mechanism that changed the color of our dining room lighting.

These functions may seem difficult at first glance, but were easy to install using the IFTTT web service.

We created “otegami” (“letter” in Japanese), a gadget guaranteeing delivery of school letters and handouts at home. When a handout was placed in a clear tray, it activated a sound as well as a flag movement. That prompted an e-mail to me and changed the color of the dining room lights to red. As expected, I noticed the red lighting. We made a short video of the trial run.
（https://youtu.be/xqYPw-6wLeQ）

*CdS cell 30 yen
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/g/gI-00110/)
*Resistor １０kΩ approximately 1 yen
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/g/gR-25103/)
*Piezoelectric speaker 50 yen
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/g/gP-01251/)
*Servomotor E-SKY EK02 0500 about 400 yen
*Clear tray (Daiso Industries Co., Ltd.) 100 yen
*Spacer (M2.6 hexagonal screw) for attaching GR-SAKURA
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/goods/search.aspx?keyword=M2.6&maker=myg&goods=&number=&name=&min_price=&max_price=&last_sdt=&sort=&style=T&search.x=0&search.y=0)
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/g/gP-07324/)
*Breadboard jumper cord (pliable jumper wire)
 (Akizuki Denshi Tsusho Co., Ltd. http://akizukidenshi.com/catalog/g/gC-05159/)
*MicroSD 2GB about 700 yen
*Philips hue Philips LED smart lighting system (lighting changes via a wireless system)
  （http://www2.meethue.com/ja-JP）

We soldered each sensor directly with the pliable jumper cord, then attached the sensors to the GR-SAKURA. Take care to not overheat the sensors while soldering.

The clear tray is heat-sensitive, so use a soldering iron to melt holes in the tray, cleanly finishing the holes off with a screwdriver, and then attach the GR-SAKURA to the tray with the spacers. There happens to be a slit in the reverse side of the clear tray, enabling SD card retrieval at any time. The remaining parts are relatively light, and can be attached by double-sided tape, cute masking tape, or hot glue.

Wiring diagram

Front

Reverse

Attached to clear tray

Here is the sketch I made. It is not entirely correct to say that I made it, as I simply modified an existing template (GR-SAKURA_MP3_WAV_V2.07.zip) for data retrieval from SD to the mp3 wav to determine the CdS sensor level, activate the servomotor, and add IFTTT (e-mail notification and lighting control). An added function allowed me to push a button on the reverse of the gadget to reset the system after the gadget sensed arrival of a letter and notified me.

/*
 * gr_sketch.cpp - wavmp3p library
 * Copyright (c) 2015 Mitsuhiro Matsuura.  All right reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/* This template is based on GR-SAKURA Sketch Template V2.07 */

#include 
#include 
#include 
#include 
#include 
#include 
// servo ^^
#include 
#define INTERVAL 50
int val=0; 
// servo vv


#define LED_ON		HIGH
#define LED_OFF		LOW

#define Serial Serial1
#define SW_PAUSE	5
#define SW_SKIP		4
#define SW_ON		0
#define SW_OFF		1


Servo servo0;

// IFTTT ^^^
//#define USE_SERIAL

// Enter a MAC address and IP address for your controller below.
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; // MAC

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;
char server[] = "maker.ifttt.com";

// IFTTT strings
char eventName[] = "otegami"; // Enter THIS event name for your recipe
char secretKey[] = "d6nhkuCDkhqCgQFAgNtNMr"; // Enter your secret key
char s[128];
int val1, val2, val3;

int frg = 0;

// IFTTT vvv


WavMp3p wavmp3p(44100);
File root;

static
void cyclic_handler(void);

void setup()
{
 //   Serial.begin(9600);	
	
// servo ^^
    pinMode(PIN_SW, INPUT);
    servo0.attach(9);
    servo0.write(90);
    

// servo vv
    
	Serial.begin(115200);
	Serial.println("wav & mp3 player");

	pinMode(PIN_LED0, OUTPUT);
	digitalWrite(PIN_LED0, LED_ON);

	while(!SD.begin())
	{
		Serial.println("Card failed, or not present.");
		digitalWrite(PIN_LED0, LED_OFF);
		delay(1000);
		digitalWrite(PIN_LED0, LED_ON);
	}

	pinMode(SW_PAUSE, INPUT_PULLUP);
	pinMode(SW_SKIP, INPUT_PULLUP);

	MsTimer2::set(100, cyclic_handler);
	MsTimer2::start();
	
	
	// IFTTT ^^^^
	    pinMode(PIN_LED0, OUTPUT); // check to start
    pinMode(PIN_LED1, OUTPUT); // check to begin Ether
    pinMode(PIN_LED2, OUTPUT); // check to connect IFTTT
    pinMode(PIN_LED3, OUTPUT); // check to finish sending HTTP
    pinMode(PIN_SW, INPUT);

    // Open serial communications and wait for port to open
#ifdef USE_SERIAL
    Serial.begin(9600); // for debug
    while (!Serial.available())
        ; // key wait
    Serial.println("start to begin Ether.");
#endif

    digitalWrite(PIN_LED0, HIGH);

    // start the Ethernet connection:
    while (!Ethernet.begin(mac)) {
#ifdef USE_SERIAL
        Serial.println("Failed to configure Ethernet using DHCP");
#endif
    }
    digitalWrite(PIN_LED1, HIGH); // success to begin

#ifdef USE_SERIAL
    // print your local IP address:
    Serial.print("My IP address: ");  // for debug
    Serial.println(Ethernet.localIP());  // for debug
    Serial.println("Push blue SW on GR-SAKURA to start.");  // for debug
#endif

// IFTTT vvvv
	
}

#if 1
// ƒtƒ@ƒCƒ‹–¼‚ðŒˆ‚ß‘Å‚¿‚·‚éƒTƒ“ƒvƒ‹
void loop()
{
	// Ä¶
//	wavmp3p.play("1.mp3");
//	wavmp3p.play("2.mp3");
	
//wavmp3p.play("1.wav");
//	wavmp3p.play("2.wav");

val=analogRead(0);
//Serial.println(val); //入力された値をモニターに出力

    delay(500);


// IFTTT ^^^
// 青ボタンを押した時にfrgを0に
   if (digitalRead(PIN_SW) == LOW) {
    frg=0;
    // wav play ^^^
    wavmp3p.play("2.mp3");
}

   if(frg == 0 && val > 390){
    frg=1;
// wav play ^^^
    wavmp3p.play("1.wav");
// servo move
        servo0.write(45);
        delay(1000);
        servo0.write(90);
        delay(1000);
        servo0.write(135);
        delay(1000);
        servo0.write(90);
        delay(1000);
        servo0.write(45);
        delay(1000);
        servo0.write(90);
        delay(1000);
        servo0.write(135);
        delay(1000);
        servo0.write(90);
        delay(1000);
         


        // if you get a connection, report back via serial:
        if (client.connect(server, 80)) {
            digitalWrite(PIN_LED2, HIGH);
#ifdef USE_SERIAL
            Serial.println("connected to IFTTT server");  // for debug
#endif
            // Make a HTTP request:
            sprintf(s,
                    "GET http://maker.ifttt.com/trigger/%s/with/key/%s HTTP/1.1",
                    eventName, secretKey);
#ifdef USE_SERIAL
            Serial.println(s); // for debug
#endif
            client.println(s);
            client.println("Host: maker.ifttt.com");
            client.println("Connection: close");
            client.println();
            digitalWrite(PIN_LED3, HIGH);
            delay(500);
        }
        else {
            // if you didn't get a connection to the server:
#ifdef USE_SERIAL
            Serial.println("connection failed");  // for debug
#endif
        }
        digitalWrite(PIN_LED2, LOW);
        digitalWrite(PIN_LED3, LOW);
    }

    if (client.available()) {
        char c = client.read();
#ifdef USE_SERIAL
        Serial.print(c);
#endif
    }

    if (!client.connected()) {
        client.stop();
    }
    // IFTTT vvv


}

#else
// This sample plays the .wav or .mp3 in a card in order.
// ƒJ[ƒh‚Ì.wav ‚Ü‚½‚Í .mp3 ƒtƒ@ƒCƒ‹‚ðŒ©‚Â‚¯‚½‡‚ɍж‚·‚éƒTƒ“ƒvƒ‹
char path[1024][8+1+3+1];

void printDirectory(File dir, int numTabs)
{
	while(true)
	{
		File entry = dir.openNextFile();

		if(!entry)
		{
			return;
		}

		if(entry.isDirectory())
		{
			strcpy(path[numTabs], entry.name());
			printDirectory(entry, numTabs + 1);
		}
		else
		{
			char fpath[1024] = "";
			for(uint8_t i=0; i< numTabs; i++)
			{
				strcat(fpath, path[i]);
				strcat(fpath, "/");
			}
			strcat(fpath, entry.name());
			Serial.print(fpath);

			char *res = wavmp3p.play(fpath);
			if(res)Serial.println(res);
		}
	}
}

void loop()
{
	root = SD.open("/");
	printDirectory(root, 0);
	Serial.println("done!");
}
#endif

// The below handler enables to skip or stop.
// ˆêŽž’âŽ~CƒXƒLƒbƒv‹@”\‚̃Tƒ“ƒvƒ‹
static
void cyclic_handler()
{
	static int ct_pause = 0;

	if(SW_ON == digitalRead(SW_PAUSE)){
		if(ct_pause == 2){
			if(wavmp3p.read_pause()){
				wavmp3p.pause(0);
				digitalWrite(PIN_LED0, LED_ON);
			}else{
				wavmp3p.pause(1);
				digitalWrite(PIN_LED0, LED_OFF);
			}
			ct_pause++;
		}else if(ct_pause < 2){
			ct_pause++;
		}
	}else{
		ct_pause = 0;
	}

	static int ct_skip = 0;

	if(SW_ON == digitalRead(SW_SKIP)){
		if(ct_skip == 2){
			wavmp3p.skip();
			digitalWrite(PIN_LED0, LED_ON);
			ct_skip++;
		}else if(ct_skip < 2){
			ct_skip++;
		}
	}else{
		ct_skip = 0;
	}
}

IFTTT allows Web services such as Facebook, Twitter, and e-mail to be linked. It can be set up using a Web application (http://ifttt.com). There are many services facilitating such links, one of which is MakerChannel, which works to link Arduino. I used it to dispatch e-mail, etc. from Arduino via IFTTT.

I used the following references to create this gadget.

- No 5V output during the initial stage.
Use the pink-hued GR-SAKURA microprocessor and LED to create a breathalyzer for your next cherry blossom outing! http://liginc.co.jp/264119

- How to use a CdS sensor
#5 Try using optic sensor for Arduino data entry! http://deviceplus.jp/hobby/entry_005/

- Serial communication using Web compiler with GR-SAKURA
Gadget Renesas Community: how to use and apply SAKURA (see bottom of page) http://japan.renesasrulz.com/gr_user_forum_japanese/b/weblog2/archive/2015/07/05/sakura.aspxn

- How to use a servomotor
SAKURA sketch reference → servomotor http://gadget.renesas.com/ja/reference/sakura/library_servo.html

- How to use SD to view wav and mp3
Web compiler template: GR-SAKURA_MP3_WAV_V2.07.zip

- How to use IFTTT
Web compiler template: GR-SAKURA_IFTTT_V2.03.zip