Arduino Basics: UNO
Showing posts with label UNO. Show all posts
Showing posts with label UNO. Show all posts

18 July 2015

NeoPixel Heart Beat Display


Project Description


In this project, your heart will control a mesmerising LED sequence on a 5 metre Neopixel LED strip with a ws2812B chipset. Every heart beat will trigger a LED animation that will keep you captivated and attached to your Arduino for ages. The good thing about this project is that it is relatively easy to set up, and requires no soldering. The hardest part is downloading and installing the FastLED library into the Arduino IDE, but that in itself is not too difficult. The inspiration and idea behind this project came from Ali Murtaza, who wanted to know how to get an LED strip to pulse to his heart beat.
 
Have a look at the video below to see this project in action.
 
 
 

The Video


 


 
 

Parts Required:


 

Power Requirements

Before you start any LED strip project, the first thing you will need to think about is POWER. According to the Adafruit website, each individual NeoPixel LED can draw up to 60 milliamps at maximum brightness - white. Therefore the amount of current required for the entire strip will be way more than your Arduino can handle. If you try to power this LED strip directly from your Arduino, you run the risk of damaging not only your Arduino, but your USB port as well. The Arduino will be used to control the LED strip, but the LED strip will need to be powered by a separate power supply. The power supply you choose to use is important. It must provide the correct voltage, and must able to supply sufficient current.
 

Operating Voltage (5V)

The operating voltage of the NeoPixel strip is 5 volts DC. Excessive voltage will damage/destroy your NeoPixels.

Current requirements (9.0 Amps)

OpenLab recommend the use of a 5V 10A power supply. Having more Amps is OK, providing the output voltage is 5V DC. The LEDs will only draw as much current as they need. To calculate the amount of current this 5m strip can draw with all LEDs turned on at full brightness - white:

30 NeoPixel LEDs x 60mA x 5m = 9000mA = 9.0 Amps for a 5 metre strip.

Therefore a 5V 10A power supply would be able to handle the maximum current (9.0 Amps) demanded by a 5m NeoPixel strip containing a total of 150 LEDs.
 
 


Arduino Libraries and IDE


Before you start to hook up any components, upload the following sketch to the Arduino microcontroller. I am assuming that you already have the Arduino IDE installed on your computer. If not, the IDE can be downloaded from here.
 
The FastLED library is useful for simplifying the code for programming the NeoPixels. The latest "FastLED library" can be downloaded from here. I used FastLED library version 3.0.3 in this project.
 
If you have a different LED strip or your NeoPixels have a different chipset, make sure to change the relevant lines of code to accomodate your hardware. I would suggest you try out a few of the FastLED library examples before using the code below, so that you become more familiar with the library, and will be better equipped to make the necessary changes. If you have a 5 metre length of the NeoPixel 30 LED/m strip with the ws2812B chipset, then you will not have to make any modification below.
 

ARDUINO CODE:


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/* ================================================================================================ Project: NeoPixel Heart Beat Display Neopixel chipset: ws2812B (30 LED/m strip) Author: Scott C Created: 8th July 2015 Arduino IDE: 1.6.4 Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html Description: This sketch will display a heart beat on a 5m Neopixel LED strip. Requires a Grove Ear-clip heart rate sensor and a Neopixel strip. This project makes use of the FastLED library: http://fastled.io/ You may need to modify the code below to accomodate your specific LED strip. See the FastLED library site for more details. ================================================================================================== */ //This project needs the FastLED library - link in the description. #include "FastLED.h" //The total number of LEDs being used is 150 #define NUM_LEDS 150 // The data pin for the NeoPixel strip is connected to digital Pin 6 on the Arduino #define DATA_PIN 6 //Attach the Grove Ear-clip heart rate sensor to digital pin 2 on the Arduino. #define EAR_CLIP 2 //Initialise the LED array CRGB leds[NUM_LEDS]; //Initialise the global variables used to control the LED animation int ledNum = 0; //Keep track of the LEDs boolean beated = false; //Used to identify when the heart has beated int randomR = 0; //randomR used to randomise the fade-out of the LEDs //================================================================================================ // setup() : Is used to initialise the LED strip //================================================================================================ void setup() { FastLED.addLeds<NEOPIXEL,DATA_PIN>(leds, NUM_LEDS); //Set digital pin 2 (Ear-clip heart rate sensor) as an INPUT pinMode(EAR_CLIP, INPUT); } //================================================================================================ // loop() : Take readings from the Ear-clip sensor, and display the animation on the LED strip //================================================================================================ void loop() { //If the Ear-clip sensor moves from LOW to HIGH, call the beatTriggered method if(digitalRead(EAR_CLIP)>0){ //beatTriggered() is only called if the 'beated' variable is false. //This prevents multiple triggers from the same beat. if(!beated){ beatTriggered(); } } else { beated = false; //Change the 'beated' variable to false when the Ear-clip heart rate sensor is reading LOW. } //Fade the LEDs by 1 unit/cycle, when the heart is at 'rest' (i.e. between beats) fadeLEDs(5); } //================================================================================================ // beatTriggered() : This is the LED animation sequence when the heart beats //================================================================================================ void beatTriggered(){ //Ignite 30 LEDs with a red value between 0 to 255 for(int i = 0; i<30; i++){ //The red channel is randomised to a value between 0 to 255 leds[ledNum].r=random8(); FastLED.show(); //Call the fadeLEDs method after every 3rd LED is lit. if(ledNum%3==0){ fadeLEDs(5); } //Move to the next LED ledNum++; //Make sure to move back to the beginning if the animation falls off the end of the strip if(ledNum>(NUM_LEDS-1)){ ledNum=0; } } //Ignite 20 LEDS with a blue value between 0 to 120 for(int i = 0; i<20; i++){ //The blue channel is randomised to a value between 0 to 120 leds[ledNum].b=random8(120); FastLED.show(); //Call the fadeLEDs method after every 3rd LED is lit. if(ledNum%3==0){ fadeLEDs(5); } //Move to the next LED ledNum++; //Make sure to move back to the beginning if the animation falls off the end of the strip if(ledNum>(NUM_LEDS-1)){ ledNum=0; } } //Change the 'beated' variable to true, until the Ear-Clip sensor reads LOW. beated=true; } //================================================================================================ // fadeLEDs() : The fading effect of the LEDs when the Heart is resting (Ear-clip reads LOW) //================================================================================================ void fadeLEDs(int fadeVal){ for (int i = 0; i<NUM_LEDS; i++){ //Fade every LED by the fadeVal amount leds[i].fadeToBlackBy( fadeVal ); //Randomly re-fuel some of the LEDs that are currently lit (1% chance per cycle) //This enhances the twinkling effect. if(leds[i].r>10){ randomR = random8(100); if(randomR<1){ //Set the red channel to a value of 80 leds[i].r=80; //Increase the green channel to 20 - to add to the effect leds[i].g=20; } } } FastLED.show(); }


 

NeoPixel Strip connection

The NeoPixel strip is rolled up when you first get it. You will notice that there are wires on both sides of the strip. This allows you to chain LED strips together to make longer strips. The more LEDs you have, the more current you will need. Connect your Arduino and power supply to the left side of the strip, with the arrows pointing to the right. (i.e. the side with the "female" jst connector).
 



NeoPixel Strip Wires

There are 5 wires that come pre-attached to either side of the LED strip.
 

 
You don't have to use ALL FIVE wires, however you will need at least one of each colour: red, white & green.
 

 

Fritzing sketch

The following diagram will show you how to wire everything together
 
(click to enlarge)

Arduino Power considerations

Please note that the Arduino is powered by a USB cable.
If you plan to power the Arduino from your power supply, you will need to disconnect the USB cable from the Arduino FIRST, then connect a wire from the 5V line on the Power supply to the 5V pin on the Arduino. Do NOT connect the USB cable to the Arduino while the 5V wire is connected to the Arduino.
 

 

Large Capacitor

Adafruit also recommend the use of a large capacitor across the + and - terminals of the LED strip to "prevent the initial onrush of current from damaging the pixels". Adafruit recommends a capacitor that is 1000uF, 6.3V or higher. I used a 4700uF 16V Electrolytic Capacitor.
 

 

Resistor on Data Pin

Another recommendation from Adafruit is to place a "300 to 500 Ohm resistor" between the Arduino's data pin and the data input on the first NeoPixel to prevent voltage spikes that can damage the first pixel. I used a 330 Ohm resistor.
 

 

Grove Ear-clip heart rate sensor connection

The Grove Base shield makes it easy to connect Grove modules to the Arduino. If you have a Grove Base shield, you will need to connect the Ear-clip heart rate sensor to Digital pin 2 as per the diagram below.
 

 

Completed construction

Once you have everything connected, you can plug the USB cable into the Arduino, and turn on the LED power supply. Attach the ear-clip to your ear (or to your finger) and allow a few seconds to allow the sensor to register your pulse. The LED strip will light up with every heart beat with an animation that moves from one end of the strip to the other in just three heart beats. When the ear-clip is not connected to your ear or finger, the LEDs should remain off. However, the ear clip may "trigger" a heart beat when opening or closing the clip.
 
Here is a picture of all the components (fully assembled).
 


Concluding comments


This very affordable LED strip allows you to create amazing animations over a greater distance. I thought that having less LEDs per metre would make the animations look "jittery", but I was wrong, they look amazing. One of the good things about this strip is the amount of space between each Neopixel, allowing you to easily cut and join the strip to the size and shape you need.
 
This LED strip is compatible with the FastLED library, which makes for easy LED animation programming. While I used this LED strip to display my heart beat, you could just as easily use it to display the output of any other sensor attached to the Arduino.
 



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7 May 2015

CH376S USB Read/Write module

Have you ever wondered if there was a way to store and retrieve data from a USB stick with an Arduino UNO? Most people choose SD cards to store their project data, but you may be surprised there IS a way!
IC Station have a nice little module which allows you store and retrieve your Arduino (or other MCU) project data to a USB stick.
 
I am not too sure why USB storage is not widely used in Arduino projects? These modules are not expensive, they have been around for quite a while, and are relatively simple to use. You do not need any libraries to get them to work, however, I must say that documentation for this module is not that easy to find. This site and this document proved to be very useful in my endevour to get this module working, and I hope my tutorial below will help you get started and bridge some of the information gaps.
 
The "CH376S USB read/write module" has a CH376S chip onboard which does most of the hard work for you. All you have to do is send the module some commands from the Arduino and the CH376S chip will do the rest. You can communicate with the module in three different ways:

  • Parallel communication
  • SPI communication
  • and Serial (UART) communication.

This project will show you the connections and code for the Serial (UART) communication method only.


 

Parts Required:

Remove the Jumper

When the CH376S USB module arrives in it's package, it will have a jumper between the TXD pin and GND. You will need to remove this jumper to make the necessary connections between the Arduino UNO and the CH376S USB module.


 

Fritzing Sketch

Please note, that the Arduino Sketch makes use of the Arduino UNO's onboard LED on digital pin 13. The Fritzing sketch below shows an LED + 300 ohm resistor on a breadboard. This is optional. The LED is not a necessary component of CH376S module communication.

Also be aware that the CH376S USB module has an onboard LED just above the TXD and GND pins near the USB port. This LED will only turn on providing the CH376S module is in USB mode AND a USB device has been inserted into the USB port. Both conditions must be met before the module's onboard LED will illuminate. You will not see the LED turn on just by powering the board.
 
The wire diagram below is the correct setup for Serial communication between an Arduino UNO and the CH376S module. If you wish to use SPI or Parallel communication, you will need to refer to the datasheet.


 
 

Arduino Sketch


 
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/* ===============================================================
      Project: CH376S USB Read/Write Module testing ground
       Author: Scott C
      Created: 1st May 2015
  Arduino IDE: 1.6.2
      Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html
  Description: This project will allow you to perform many of the functions available on the CH376S module.
               Checking connection to the module, putting the module into USB mode, resetting the module, 
               reading, writing, appending text to files on the USB stick. This is very useful alternative to
               SD card modules, plus it doesn't need any libraries.
================================================================== */

#include <SoftwareSerial.h>

byte computerByte;           //used to store data coming from the computer
byte USB_Byte;               //used to store data coming from the USB stick
int LED = 13;                //the LED is connected to digital pin 13 
int timeOut = 2000;          //TimeOut is 2 seconds. This is the amount of time you wish to wait for a response from the CH376S module.
String wrData = "What is the meaning of life ?";     //We will write this data to a newly created file.
String wrData2 = "42";                                   //We will append this data to an already existing file.

SoftwareSerial USB(10, 11);                           // Digital pin 10 on Arduino (RX) connects to TXD on the CH376S module
                                                      // Digital pin 11 on Arduino (TX) connects to RXD on the CH376S module
                                                      // GND on Arduino to GND on CH376S module
                                                      // 5V on Arduino to 5V on CH376S module
//==============================================================================================================================================
void setup() {
  Serial.begin(9600);                                 // Setup serial communication with the computer (using a baud rate of 9600 on serial monitor)
  USB.begin(9600);                                    // Setup serial communication with the CH376S module (using the default baud rate of 9600)
  pinMode(LED,OUTPUT);                                // Define digital pin 13 as an OUTPUT pin - so that we can use it with an LED
  digitalWrite(LED,LOW);                              // Turn off the LED
}

//================================================================================================================================================
void loop() {
  if(Serial.available()){
    computerByte = Serial.read();                      //read any incoming bytes from the Serial monitor, and store this byte in the variable called computerByte
    if(computerByte==49){               //1            //If you send the number 1 from the serial monitor, the arduino will read it as digital number 49. Google "ascii table" for more info.
      printCommandHeader("COMMAND1: CHECK CONNECTION");
      checkConnection(0x01);                           // Check for successful connection and communication with the CH376S module.
    } 
    if(computerByte==50){               //2
     printCommandHeader("COMMAND2: set_USB_Mode");
      set_USB_Mode(0x06);                              // Code used to enable read/write communication and monitoring of the USB stick
    }
    if(computerByte==51){               //3
      printCommandHeader("COMMAND3: resetALL");
      resetALL();                                      // Reset the USB device
    }
    if(computerByte==52){               //4
      printCommandHeader("COMMAND4: Create and Write to File : TEST4.TXT");
      writeFile("TEST4.TXT", wrData);                  // Create a file called TEST4.TXT and then Write the contents of wrData to this file
    }
    if(computerByte==53){               //5
      printCommandHeader("COMMAND5: Read File: TEST4.TXT");
      readFile("TEST4.TXT");                           // Read the contents of this file on the USB disk, and display contents in the Serial Monitor
    }
    if(computerByte==54){               //6
      printCommandHeader("COMMAND6: Append data to file: TEST4.TXT");
      appendFile("TEST4.TXT", wrData2);                // Append data to the end of the file.
    }
    if(computerByte==55){               //7
      printCommandHeader("COMMAND7: Delete File: TEST4.TXT");
      fileDelete("TEST4.TXT");                         // Delete the file named TEST4.TXT
    }
    if(computerByte==56){               //8
      printCommandHeader("COMMAND8: Read File: TEST2.TXT");
      readFile("TEST2.TXT");                           // Read the contents of the TEST2.TXT file on the USB disk, and display contents in the Serial Monitor
    }
    if(computerByte==57){               //9
      printCommandHeader("COMMAND9: Read File: TEST3.TXT");
      readFile("TEST3.TXT");                           // Read the contents of the TEST3.TXT file on the USB disk, and display contents in the Serial Monitor
    }
  }
  
  if(USB.available()){                                 // This is here to capture any unexpected data transmitted by the CH376S module
    Serial.print("CH376S has just sent this code:");
    Serial.println(USB.read(), HEX);
  }
}

//END OF LOOP FUNCTION ========================================================================================================================================

//print Command header
void printCommandHeader(String header){
   Serial.println("======================");
   Serial.println("");
   Serial.println(header);
   Serial.println("----------------------");
}

//checkConnection==================================================================================
//This function is used to check for successful communication with the CH376S module. This is not dependant of the presence of a USB stick.
//Send any value between 0 to 255, and the CH376S module will return a number = 255 - value. 
void checkConnection(byte value){
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x06);
  USB.write(value);
  
  if(waitForResponse("checking connection")){       //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
    if(getResponseFromUSB()==(255-value)){
       Serial.println(">Connection to CH376S was successful.");
       blinkLED();                               //blink the LED for 1 second if the connection was successful
    } else {
      Serial.print(">Connection to CH376S - FAILED.");
    }
  }
}

//set_USB_Mode=====================================================================================
//Make sure that the USB is inserted when using 0x06 as the value in this specific code sequence
void set_USB_Mode (byte value){
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x15);
  USB.write(value);
  
  delay(20);
  
  if(USB.available()){
    USB_Byte=USB.read();
    //Check to see if the command has been successfully transmitted and acknowledged.
    if(USB_Byte==0x51){                                   // If true - the CH376S has acknowledged the command.
        Serial.println("set_USB_Mode command acknowledged"); //The CH376S will now check and monitor the USB port
        USB_Byte = USB.read();
        
        //Check to see if the USB stick is connected or not.
        if(USB_Byte==0x15){                               // If true - there is a USB stick connected
          Serial.println("USB is present");
          blinkLED();                                     // If the process was successful, then turn the LED on for 1 second 
        } else {
          Serial.print("USB Not present. Error code:");   // If the USB is not connected - it should return an Error code = FFH
          Serial.print(USB_Byte, HEX);
          Serial.println("H");
        }
        
    } else {
        Serial.print("CH3765 error!   Error code:");
        Serial.print(USB_Byte, HEX);
        Serial.println("H");
    }   
  }
  delay(20);
}

//resetALL=========================================================================================
//This will perform a hardware reset of the CH376S module - which usually takes about 35 msecs =====
void resetALL(){
    USB.write(0x57);
    USB.write(0xAB);
    USB.write(0x05);
    Serial.println("The CH376S module has been reset !");
    delay(200);
}

//readFile=====================================================================================
//This will send a series of commands to read data from a specific file (defined by fileName)
void readFile(String fileName){
  resetALL();                     //Reset the module
  set_USB_Mode(0x06);             //Set to USB Mode
  diskConnectionStatus();         //Check that communication with the USB device is possible
  USBdiskMount();                 //Prepare the USB for reading/writing - you need to mount the USB disk for proper read/write operations.
  setFileName(fileName);          //Set File name
  fileOpen();                     //Open the file for reading
  int fs = getFileSize();         //Get the size of the file
  fileRead();                     //***** Send the command to read the file ***
  fileClose(0x00);                //Close the file
}

//writeFile========================================================================================
//is used to create a new file and then write data to that file. "fileName" is a variable used to hold the name of the file (e.g TEST.TXT). "data" should not be greater than 255 bytes long. 
void writeFile(String fileName, String data){
  resetALL();                     //Reset the module
  set_USB_Mode(0x06);             //Set to USB Mode
  diskConnectionStatus();         //Check that communication with the USB device is possible
  USBdiskMount();                 //Prepare the USB for reading/writing - you need to mount the USB disk for proper read/write operations.
  setFileName(fileName);          //Set File name
  if(fileCreate()){               //Try to create a new file. If file creation is successful
    fileWrite(data);              //write data to the file.
  } else {
    Serial.println("File could not be created, or it already exists");
  }
  fileClose(0x01);
}

//appendFile()====================================================================================
//is used to write data to the end of the file, without erasing the contents of the file.
void appendFile(String fileName, String data){
    resetALL();                     //Reset the module
    set_USB_Mode(0x06);             //Set to USB Mode
    diskConnectionStatus();         //Check that communication with the USB device is possible
    USBdiskMount();                 //Prepare the USB for reading/writing - you need to mount the USB disk for proper read/write operations.
    setFileName(fileName);          //Set File name
    fileOpen();                     //Open the file
    filePointer(false);             //filePointer(false) is to set the pointer at the end of the file.  filePointer(true) will set the pointer to the beginning.
    fileWrite(data);                //Write data to the end of the file
    fileClose(0x01);                //Close the file using 0x01 - which means to update the size of the file on close. 
}
  
//setFileName======================================================================================
//This sets the name of the file to work with
void setFileName(String fileName){
  Serial.print("Setting filename to:");
  Serial.println(fileName);
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x2F);
  USB.write(0x2F);         // Every filename must have this byte to indicate the start of the file name.
  USB.print(fileName);     // "fileName" is a variable that holds the name of the file.  eg. TEST.TXT
  USB.write((byte)0x00);   // you need to cast as a byte - otherwise it will not compile.  The null byte indicates the end of the file name.
  delay(20);
}

//diskConnectionStatus================================================================================
//Check the disk connection status
void diskConnectionStatus(){
  Serial.println("Checking USB disk connection status");
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x30);

  if(waitForResponse("Connecting to USB disk")){       //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
    if(getResponseFromUSB()==0x14){               //CH376S will send 0x14 if this command was successful
       Serial.println(">Connection to USB OK");
    } else {
      Serial.print(">Connection to USB - FAILED.");
    }
  }
}

//USBdiskMount========================================================================================
//initialise the USB disk and check that it is ready - this process is required if you want to find the manufacturing information of the USB disk
void USBdiskMount(){
  Serial.println("Mounting USB disk");
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x31);

  if(waitForResponse("mounting USB disk")){       //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
    if(getResponseFromUSB()==0x14){               //CH376S will send 0x14 if this command was successful
       Serial.println(">USB Mounted - OK");
    } else {
      Serial.print(">Failed to Mount USB disk.");
    }
  }
}

//fileOpen========================================================================================
//opens the file for reading or writing
void fileOpen(){
  Serial.println("Opening file.");
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x32);
  if(waitForResponse("file Open")){                 //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
    if(getResponseFromUSB()==0x14){                 //CH376S will send 0x14 if this command was successful  
       Serial.println(">File opened successfully.");
    } else {
      Serial.print(">Failed to open file.");
    }
  }
}

//setByteRead=====================================================================================
//This function is required if you want to read data from the file. 
boolean setByteRead(byte numBytes){
  boolean bytesToRead=false;
  int timeCounter = 0;
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x3A);
  USB.write((byte)numBytes);   //tells the CH376S how many bytes to read at a time
  USB.write((byte)0x00);
  if(waitForResponse("setByteRead")){       //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
    if(getResponseFromUSB()==0x1D){         //read the CH376S message. If equal to 0x1D, data is present, so return true. Will return 0x14 if no data is present.
      bytesToRead=true;
    }
  }
  return(bytesToRead);
} 

//getFileSize()===================================================================================
//writes the file size to the serial Monitor.
int getFileSize(){
  int fileSize=0;
  Serial.println("Getting File Size");
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x0C);
  USB.write(0x68);
  delay(100);
  Serial.print("FileSize =");
  if(USB.available()){
    fileSize = fileSize + USB.read();
  } 
  if(USB.available()){
    fileSize = fileSize + (USB.read()*255);
  } 
  if(USB.available()){
    fileSize = fileSize + (USB.read()*255*255);
  } 
  if(USB.available()){
    fileSize = fileSize + (USB.read()*255*255*255);
  }     
  Serial.println(fileSize);
  delay(10);
  return(fileSize);
}


//fileRead========================================================================================
//read the contents of the file
void fileRead(){
  Serial.println("Reading file:");
  byte firstByte = 0x00;                     //Variable to hold the firstByte from every transmission.  Can be used as a checkSum if required.
  byte numBytes = 0x40;                      //The maximum value is 0x40  =  64 bytes
 
  while(setByteRead(numBytes)){              //This tells the CH376S module how many bytes to read on the next reading step. In this example, we will read 0x10 bytes at a time. Returns true if there are bytes to read, false if there are no more bytes to read.
    USB.write(0x57);
    USB.write(0xAB);
    USB.write(0x27);                          //Command to read ALL of the bytes (allocated by setByteRead(x))
    if(waitForResponse("reading data")){      //Wait for the CH376S module to return data. TimeOut will return false. If data is being transmitted, it will return true.
        firstByte=USB.read();                 //Read the first byte
        while(USB.available()){
          Serial.write(USB.read());           //Send the data from the USB disk to the Serial monitor
          delay(1);                           //This delay is necessary for successful Serial transmission
        }
    }
    if(!continueRead()){                       //prepares the module for further reading. If false, stop reading.
      break;                                   //You need the continueRead() method if the data to be read from the USB device is greater than numBytes.
    }
  }
  Serial.println();
  Serial.println("NO MORE DATA");
}

//fileWrite=======================================================================================
//are the commands used to write to the file
void fileWrite(String data){
  Serial.println("Writing to file:");
  byte dataLength = (byte) data.length();         // This variable holds the length of the data to be written (in bytes)
  Serial.println(data);
  Serial.print("Data Length:");
  Serial.println(dataLength);
  delay(100);
  // This set of commands tells the CH376S module how many bytes to expect from the Arduino.  (defined by the "dataLength" variable)
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x3C);
  USB.write((byte) dataLength);
  USB.write((byte) 0x00);
  if(waitForResponse("setting data Length")){      // Wait for an acknowledgement from the CH376S module before trying to send data to it
    if(getResponseFromUSB()==0x1E){                // 0x1E indicates that the USB device is in write mode.
      USB.write(0x57);
      USB.write(0xAB);
      USB.write(0x2D);
      USB.print(data);                             // write the data to the file
  
      if(waitForResponse("writing data to file")){   // wait for an acknowledgement from the CH376S module
      }
      Serial.print("Write code (normally FF and 14): ");
      Serial.print(USB.read(),HEX);                // code is normally 0xFF
      Serial.print(",");
      USB.write(0x57);
      USB.write(0xAB);
      USB.write(0x3D);                             // This is used to update the file size. Not sure if this is necessary for successful writing.
      if(waitForResponse("updating file size")){   // wait for an acknowledgement from the CH376S module
      }
      Serial.println(USB.read(),HEX);              //code is normally 0x14
    }
  }
}

//continueRead()==================================================================================
//continue to read the file : I could not get this function to work as intended.
boolean continueRead(){
  boolean readAgain = false;
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x3B);
  if(waitForResponse("continueRead")){       //wait for a response from the CH376S. If CH376S responds, it will be true. If it times out, it will be false.
     if(getResponseFromUSB()==0x14){         //CH376S will send 0x14 if this command was successful
       readAgain=true;
     }
  }
  return(readAgain);
} 

//fileCreate()========================================================================================
//the command sequence to create a file
boolean fileCreate(){
  boolean createdFile = false;
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x34);
  if(waitForResponse("creating file")){       //wait for a response from the CH376S. If file has been created successfully, it will return true.
     if(getResponseFromUSB()==0x14){          //CH376S will send 0x14 if this command was successful
       createdFile=true;
     }
  }
  return(createdFile);
}


//fileDelete()========================================================================================
//the command sequence to delete a file
void fileDelete(String fileName){
  setFileName(fileName);
  delay(20);
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x35);
  if(waitForResponse("deleting file")){       //wait for a response from the CH376S. If file has been created successfully, it will return true.
     if(getResponseFromUSB()==0x14){          //CH376S will send 0x14 if this command was successful
       Serial.println("Successfully deleted file");
     }
  }
}
  

//filePointer========================================================================================
//is used to set the file pointer position. true for beginning of file, false for the end of the file.
void filePointer(boolean fileBeginning){
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x39);
  if(fileBeginning){
    USB.write((byte)0x00);             //beginning of file
    USB.write((byte)0x00);
    USB.write((byte)0x00);
    USB.write((byte)0x00);
  } else {
    USB.write((byte)0xFF);             //end of file
    USB.write((byte)0xFF);
    USB.write((byte)0xFF);
    USB.write((byte)0xFF);
  }
  if(waitForResponse("setting file pointer")){       //wait for a response from the CH376S. 
     if(getResponseFromUSB()==0x14){                 //CH376S will send 0x14 if this command was successful
       Serial.println("Pointer successfully applied");
     }
  }
}


//fileClose=======================================================================================
//closes the file
void fileClose(byte closeCmd){
  Serial.println("Closing file:");
  USB.write(0x57);
  USB.write(0xAB);
  USB.write(0x36);
  USB.write((byte)closeCmd);                                // closeCmd = 0x00 = close without updating file Size, 0x01 = close and update file Size

  if(waitForResponse("closing file")){                      // wait for a response from the CH376S. 
     byte resp = getResponseFromUSB();
     if(resp==0x14){                                        // CH376S will send 0x14 if this command was successful
       Serial.println(">File closed successfully.");
     } else {
       Serial.print(">Failed to close file. Error code:");
       Serial.println(resp, HEX);
     }  
  }
}

//waitForResponse===================================================================================
//is used to wait for a response from USB. Returns true when bytes become available, false if it times out.
boolean waitForResponse(String errorMsg){
  boolean bytesAvailable = true;
  int counter=0;
  while(!USB.available()){     //wait for CH376S to verify command
    delay(1);
    counter++;
    if(counter>timeOut){
      Serial.print("TimeOut waiting for response: Error while: ");
      Serial.println(errorMsg);
      bytesAvailable = false;
      break;
    }
  }
  delay(1);
  return(bytesAvailable);
}

//getResponseFromUSB================================================================================
//is used to get any error codes or messages from the CH376S module (in response to certain commands)
byte getResponseFromUSB(){
  byte response = byte(0x00);
  if (USB.available()){
    response = USB.read();
  }
  return(response);
}



//blinkLED==========================================================================================
//Turn an LED on for 1 second
void blinkLED(){
  digitalWrite(LED, HIGH);
  delay(1000);
  digitalWrite(LED,LOW);
}


If you copy and paste this code directly into the Arduino IDE; you may get a warning like this when you compile the code:
 
   "Low memory available, stability problems may occur".
 
I managed to run the sketch without any issues, however, I did experience problems with some of the methods when I had made further memory hungry modifications. If you do encounter problems, I would recommend that you eliminate any methods which you do not plan to use, and perhaps reduce the number of Serial.print statements throughout the code. However, please note that some of the methods will not work unless the module is in the correct state, so be careful which methods you delete. For example, I found that I could get some simple functionality without the "USBdiskMount()" method. However, I could not read/write data beyond a certain length without this method.
 
Also please note, that some of the methods called within the reading and writing sequence do not need to be called every time. They can be called once in setup, while other methods within the sequence will need to be called every time. I grouped them all together for simplicity.


Serial Commands

Have a look at the following presentation for a summary of the Serial commands used in this tutorial:
 


 
 



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