Conflict between Wire and SoftwareSerial?

Using Arduino Networking, Protocols, and Devices
#1

Hey guys,

I've got a few different Arduino boards here but so far I've only tried this code on the Leonardo.

I'm talking to a serial-enabled LCD via SoftwareSerial. I've also got a barometer that I'm talking to over I2C with the Wire library. Everything is fine and dandy until I run into a call to Wire.begin(). As soon as that code hits the LCD stops responding with any new text. Here's a code snippet:

#include 
#include 

SoftwareSerial lcd(3,2);

int counter = 0;

void setup() {
  lcd.begin(9600);
  clear();
}

void loop() {
  if (counter == 5) {
    Wire.begin();
  }
  clear();
  lcd.print(counter++);
  delay(1000);
}

void clear() {
  lcd.write(254);
  lcd.write(128);
  lcd.write("                ");
  lcd.write("                ");
}

void loop() {
  if (counter == 5) {
    Wire.begin();
  }
  clear();
  Serial2.print(counter++);
  delay(1000);
}

void clear() {
  Serial2.write(254);
  Serial2.write(128);
  Serial2.write("                ");
  Serial2.write("                ");
}

The LCD will count up ... 0...1...2...3...4... then nothing more, just stay on 4 forever. If I comment out Wire.begin() then everything carries on as normal. If I don't setup the serial connection to the LCD then I can read from the barometer just fine.

So it seems like there's some kind of conflict between the Wire library and SoftwareSerial. Maybe a timing issue with sending signals out at clock ticks or something? I can't image that Wire is trying to use digital pins 2 or 3 for anything...

Any help would be appreciated!

Thanks, Rob

#2 
void loop() {
  if (counter == 5) {
    Wire.begin();
  }
  clear();
  Serial2.print(counter++);
  delay(1000);
}

Code tags please, like above.

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Why are you doing Wire.begin like that? Do it in setup.

http://arduino.cc/en/Main/arduinoBoardLeonardo

TWI: 2 (SDA) and 3 (SCL). Support TWI communication using the Wire library.

You are using pins 2 and 3 both for serial and I2C. Of course you can't use them for both things at the same time. Why not use hardware serial anyway?

#3

Read the reference of the SoftwareSerial and Wire library. http://arduino.cc/en/Reference/SoftwareSerial http://arduino.cc/en/reference/wire

For the Leonardo, I2C is on pin 2 and 3 as Nick Gammon wrote. And about the SoftwareSerial library: "Not all pins on the Leonardo support change interrupts, so only the following can be used for RX: 8, 9, 10, 11, 14 (MISO), 15 (SCK), 16 (MOSI)".

#4

I'm talking to a serial-enabled LCD via SoftwareSerial.

On a board with 2 hardware serial port? When you don't use either hardware serial port? Why?

#5

The serial port on the Leonardo at pin 0 and 1 (Serial1) is a hardware serial port and it is not used for uploading a sketch or the serial monitor. So that hardware serial port is not used yet, so why don't you use it ?

#6

I'm experiencing a similar issue with MPU6050 orientation sensors and HC05 bluetooth modules on a Uno. Did you got to a solution?

(I know i'm 6 years late..)