platform：Arduino UNO, Arduino Mega2560, HC-05
Here shows the detail.
In Arduino UNO(Master), I encode
Serial.print("A 1 2 3 4 5;");
In Arduino Mega2560(slave), I encode
void setup()
{
//connect to the PC
Serial.begin(9600);
//connect to the Arduino UNO(By bluetooth)
Serial1.begin(38400);
}
void loop()
{
//its value > 0
Serial.println(Serial1.available());
//output : 128 or 248
Serial.print(Serial1.read());
delay(1000);
}
The value of Serial.available() > 0 is true,
but the print result of Serial.print(Serial1.read()); is abnormal. it print
I want to know the reason and its solution.Thanks!
I'm assuming that you made sure that both the Bluetooth devices are connected properly and the baud rates are matched.
Now, one problem might be the buffer might be full. On the sender's side, provide a delay equal to or slightly higher than the delay on the receiver's side.
Next, on the receiver side, change void loop to this:
void loop(){
if(Serial1.avaialable() > 0){
char value = Serial1.read();
Serial.println(value);
delay(1000);
}
}
Related
I want to light up a LED wirelessly through processing.
what I have so far.
I can (wirelessly) turn on my LED using a serial terminal called "Bluterm".
I can turn on my LED by pressing 1 or 0 to switch LED on and off in processing.
How can I leave Bluterm out of my equation and use processing to send the 1 and 0 through bluetooth.
Here is my code for processing:
import processing.serial.*;
Serial port;
String string;
void setup(){
String portName = Serial.list()[2]; //change the 0 to a 1 or 2 etc. to match your port
port = new Serial(this, portName, 9600);
port.bufferUntil('\n');
}
void draw() {
printArray(string);
}
void keyPressed() {
if (key =='1'){port.write('1');}
if (key=='0') {port.write('0');}
}
void serialEvent(Serial port) {
string = port.readStringUntil('\n');}
and the Arduino code
char data;
int led = 13;
void setup() {
pinMode(led, OUTPUT);
Serial.begin(9600);
}
void loop() {
if (Serial.available()>0){
data = Serial.read();
}
if (data=='1'){
Serial.println("HELLO");
digitalWrite(led, HIGH);
}
else if (data=='0'){
digitalWrite(led, LOW);
Serial.println("BYE");}
}
I'm kind of lost, can processing talk to bluetooth or do I always need a terminal?
If something isn't clear pls don't hesitate to ask,
Thank you for your time,
Juriaan
The Processing code makes sense.
It could do with a bit of formatting and error checking, but it's all pretty much there:
import processing.serial.*;
Serial port;
String string = "";
void setup() {
String portName = Serial.list()[2]; //change the 0 to a 1 or 2 etc. to match your port
try{
port = new Serial(this, portName, 9600);
port.bufferUntil('\n');
}catch(Exception e){
e.printStackTrace();
}
}
void draw() {
background(0);
text(string,10,15);
}
void keyPressed() {
if(port != null){
if (key =='1') {
port.write('1');
}
if (key=='0') {
port.write('0');
}
}
}
void serialEvent(Serial port) {
string = port.readString();
if(string == null){
println("null serial string");
string = "";
}
}
The Arduino code looks legit too.
What's unclear is what Bluetooth module you're using and how you're setting it up.
For example, if you're using something like BlueSmirf, be sure to use the guide
supplied.
The main points are:
Make sure you're using the SerialPortProfile (SPP) Bluetooth Profile
Double check you're wiring: the way your Arduino code reads you would be connect BT module's TX to Arduino's RX pin 0 and BT module's RX pin to Arduino's TX pin 1. Note you may want to do that after you upload your firmware with Arduino (as pin's 0 and 1 are Arduino's hardware Serial), otherwise goto point 3 :) (recommeded)
If you use an Arduino with multiple hardware serial ports (like Arduino mega) go with those (e.g. Serial1 instead of Serial) otherwise use a SoftwareSerial library with a low baud rate (like 9600), avoiding high baud rates.
Update
The HC-05 module uses 3.3V logic, while the Arduino uses 5V logic.
Uses a bidirectional 3.3V <-> 5V logic level converter or resistors, otherwise you risk frying your HC-05 module:
A quick search returns a detailed HowToMechatronics.com Arduino and HC-05 Bluetooth Module Tutorial
i see u are using a hc05 bluetooth device i have this myself but i dont really get what u want to use for sending the 1 and 0 to your hc05 and are you only using a led becouse if it is i would be able to help on (if you wanna send the bluetooth signals with a mobile app try the blynk app fron app store or google play store)
I am doing a project where I need to send data from ultrasonic sensor wirelessly present in one arduino to other arduino where I need these values in Serial monitor. But the problem is I cannot able to send these values through bluetooth. I tried to send one character, it is appearing in serial monitor.. But when I tried to the same for integer values it is not appearing in serial monitor.
I have configured Master and Slave modes for the Bluetooth. I have uploaded the image of the code which I am using to send these values. Please help me on this. Thanks in advance .
code
//# transmitting end
#define trigPin 12
#define echoPin 11
void setup() {
Serial.begin(38400); // Default communication rate of the Bluetooth module
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}
void loop() {
long duration;
float distance;
digitalWrite(trigPin, LOW); // Added this line
delayMicroseconds(2); // Added this line
digitalWrite(trigPin, HIGH);
delayMicroseconds(10); // Added this line
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;
Serial.println(distance,2); // Sends floatValue
delay(500);
}
//# receving end
#include <SoftwareSerial.h>
#define led 13
SoftwareSerial BTSerial(10, 11);
int data=0;
void setup() {
pinMode(led,OUTPUT);
Serial.begin(38400);
BTSerial.begin(38400); // Default communication rate of the Bluetooth module
}
void loop() {
int number;
if(Serial.available() > 0){ // Checks data is from the serial port
data = BTSerial.read(); // Reads the data from the serial port
//analogWrite(led,data);
delay(10);
//Serial.println(data);
}
Serial.println(data);
}
I need integer values at the serial monitor. But there I am getting some symbols like ?/<>..
From the Arduino reference, Serial.read() only reads the first available byte available in the Serial buffer. As an int is coded on 8 bytes, I would say that you need to read the incoming bytes sequentially in order to get the full value.
Maybe you can implement this by putting (Serial.available() > 0) in a while loop, concatenate the values you get in a char[8] for instance and then convert this char to a integer value.
Also, beware that you are sending floats and not int.
Thanks for the help..!
I modified the code in the receiver end to get the float values from the transmitter.. Here is my modified code
#include <SoftwareSerial.h>
int bluetoothTx = 10;
int bluetoothRx = 11;
String content; //content buffer to concatenate characters
char character; //To store single character
SoftwareSerial bluetooth(bluetoothTx, bluetoothRx);
void setup(){
bluetooth.begin(38400);
Serial.begin(9600);
}
void loop(){
bluetooth();
}
void bluetooth(){ //
while(bluetooth.available()){
character = bluetooth.read();
content.concat(character);
if(character == '\r'){ // find if there is carriage return
Serial.print(content); //display content (Use baud rate 9600)
content = ""; //clear buffer
Serial.println();
}
}
}
I manage to send data from NodeJs runtime with serialport library.
The goal is storing a string received from Serial.read() in Arduino . What is correct:
int string = Serial.read()
or:
char string[20] = Serial.read()
There are many documentations on Internet and they are not the same
P/s: I send string from nodejs in buffer form but i dont think it matters because arduino still implement it as a string anyway.
From the Arduino documentation:
int incomingByte = 0; // for incoming serial data
void setup() {
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
}
void loop() {
// send data only when you receive data:
if (Serial.available() > 0) {
// read the incoming byte:
incomingByte = Serial.read();
// say what you got:
Serial.print("I received: ");
Serial.println(incomingByte, DEC);
}
}
https://www.arduino.cc/en/Serial/Read
.read():
Returns the first byte of incoming serial data available (or -1 if no
data is available) - int
FYI: I've used this code many times and it works on 100%.
I'm trying to built a LED blinker using HC-05, but I encountered an error.
Here is the Arduino code:
int data = 0; //Variable for storing received data
void setup()
{
Serial.begin(9600); //Sets the baud for serial data transmission
pinMode(13, OUTPUT); //Sets digital pin 13 as output pin
}
void loop()
{
if(Serial.available()) // Send data only when you receive data:
{
data = Serial.read(); //Read the incoming data & store into data
Serial.print(data); //Print Value inside data in Serial monitor
Serial.print("\n");
if(data == 1) // Checks whether value of data is equal to 1
digitalWrite(13, HIGH); //If value is 1 then LED turns ON
else if(data == 0) // Checks whether value of data is equal to 0
digitalWrite(13, LOW); //If value is 0 then LED turns OFF
}
}
No matter which button I press on or off, the value of int data will remain same (255).
I also used many apps so I think it is not an app problem.
I found an answer to this problem.
Just change the baud rate and observe the output. My module is working perfectly on 38400.
I hope this will help you out.
I am working on a project in which I use a phone app that I built in order to use Google's Speech Recognizer, connect my phone with my Arduino via Bluetooth and then when I say a word it sends the word in order to display it in a LCD.
The phone App works great with no problems. The problem is in the Arduino code. When I say the word hello for example the Arduino receives ello. I know that it receives it because I also use the Serial monitor to display the data in my computer screen except the LCD. Then after Arduino receives the first chunk of data if I send a second word like world Arduino receives elloorld. So it not only misses again the first letter of the word but also the Serial Port is not empty it in the end of the loop.
I tried with data += c; instead of data.concat(c); and the difference is that the second word isn't elloorld and it is just orld
Here is my code:
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 9, 8, 7, 6, 5, 4, 3, 2);
char c;
String data = "";
void setup() {
lcd.begin(16, 2);
Serial.begin(9600);
}
void loop() {
lcd.clear(); //clean the lcd
lcd.home(); // set the cursor in the up left corner
while(Serial.available() > 0){
c = Serial.read();
data.concat(c);
}
if(data.length() > 0){
Serial.println(data);
}
lcd.print(data);
delay(3000);
data = "";
}
If in the end of the loop I try to clean the Serial Port with this code:
while(Serial.available() > 0){
Serial.read();
}
Then the arduino doesn't receive data at all.
Your code wakes up every 3000 ms, then processes everything that is pending in the Serial input buffer and falls asleep again.
If you remove that ugly String data and the ugly delay(3000) and the unnecessary while, you can try this simple loop:
unsigned long lastreceived;
void loop() {
if (Serial.available()) {
lcd.write(Serial.read());
lastreceived=millis();
}
if (millis() - lastreceived > 1000) {
// after one second of silence, prepare for a new message
lcd.clear();
lcd.home();
lastreceived=millis(); // don't clear too often
}
}