HC-05 transmission problem Uno R4 Minima

Official Hardware UNO Family UNO R4 Minima
1

I'm commissioning a little test rig with a newly purchased Arduino Uno R4 Minima and an HC-05 on it.

I'm having problems with high levels of noise on the transmission through the HC-05.

I'm using the schematic from this tutorial Arduino and HC-05 Bluetooth Module Tutorial | Arduino Project Hub

and this script:

// 
// Test sketch to check HC-05/HC-06 is trnsmitting correctly
// 
//

#include <SoftwareSerial.h>

// 
// Define which Arduino digital pins are used for Bluetooth receive from the HC-05/06 board and to transmit to it.
//

#define BT_SERIAL_RX 2
#define BT_SERIAL_TX 3



SoftwareSerial BTSerial (BT_SERIAL_RX, BT_SERIAL_TX);

void setup() {
  //
  // Can't use the USB Serial  at the same time as Board Pins 0 (RX) and 1 because the USB is connected to the same pins.
  // 
  Serial.begin(9600);
  BTSerial.begin(9600);
  pinMode(BT_SERIAL_RX, INPUT);
  pinMode(BT_SERIAL_TX, OUTPUT);
  Serial.println("Bluetooth Remote Control Transmit Tester Running");
  
  
    
}

void loop() {
  
  BTSerial.println("Hello");
  Serial.println("hello");
  delay(1000);
   
}

I get a high level of errors on the Blue Tooth monitor. "Hello" occasionally, but lots of error characters.

It works fine on a similar set up with a Nano.

Has anyone got any ideas what's wrong or experienced similar problems?

Thanks.

2

The R4 Uno boards have 2 hardware UARTs so you don't need to use SoftwareSerial

Connect the HC-05 to pins 0 and 1 of teh R4 and use the Serial1 object to communicate with it. Unlike the original Uno, pins 0 and 1 are not used by the Serial interface so you can use them for other purposes

3

Thanks @UKHeliBob.

Unfortunately I need to use both the built-in serial monitor and the Bluetooth.

Right now there doesn't seem to be an alternative to SoftwareSerial which is compatible with the R4, so I need to revert to one of the older processors for my purpose.

Silly me: I should have checked more thoroughly before ordering the R4.

4

What I described will allow you to do that

The Serial interface to the Serial monitor does not use pins 0 and 1 unlike the classic Uno. Pins 0 and 1 are used by the Serial1 interface as I described

6

Yes

7

Thanks @UKHeliBob I have it working now.

Apologies, I'd misread the reference to Serial1 in your original reply, and now understand the significance of that.

Unfortunately this solutions means my test rig isn't software compatible with the real target, which uses Uno R3. I now have a Nano to hand and will proceed with that for development.

Thanks again for your help.

9

Thank you