Reading 3 bytes from HC-05 Bluetooth Module

Projects Programming
1

I'm trying to read from source that is constantly outputting 3 bytes at time. It should be a number between 0 and 60 and another number.
Here is code;

#include <SoftwareSerial.h>

SoftwareSerial MyBlue(0, 1);

unsigned long number2 = 0;
uint8_t *p = (uint8_t *)&number2;
uint16_t *pNumber2 = (uint16_t *)&number2;

void setup() {
  Serial.begin(9600);
  MyBlue.begin(9600);
}

void loop() {
  if (Serial.available()) {
    uint8_t number1;
    Serial.readBytes(p, 3);
    // store number, 8bits
    number1 = p[2];
    // clear high order 16 bits -- now number2 is just the low order 16bits
    p[2] = p[3] = 0;

    char buffer[512];
    sprintf(buffer, "number1: %hu, number2: %lu, *pu: %u", (uint16_t)number1, number2, *pNumber2);
    Serial.println(buffer);
  }
}

The problem is that number2 is sometimes very large and number1 is sometimes zero. I don't understand why this is happening. I know the data is coming in very fast. Anything I am doing wrong? number2 should be between 0 & 60, and number1 should be 15. I have validated that client side is correct.

How it should work. Reads 2 numbers into 4byte buffer, unsigned long. One number is 8bits and the other is 16bits. I send them from Bluetooth client as 3 bytes. On the Arduino side, I read them into unsigned long, 3 bytes at a time; 4th byte is unused. Then assign (&buffer)[2] to 8 bit unsigned number, and &buffer to 16bit unsigned number (after clearing the most significant 16bits to 0).

Can anyone see what is wrong? Is it systematic of data coming in too fast?

Thanks!

2

Have a look at the Serial Input Basics tutorial, which among other things, shows you how to identify the start and end of a message, add separators so you can easily extract numbers, etc.

3

Using Software Serial on the hardware serial pins which you are also trying to use with the monitor is not going to be successful.

4

how can you guarantee that you always receive the 1st byte transmitted first

5

presumably you realize the code you posted is actually reading from Serial not MyBlue

i get the following when i enter "123" in the serial monitor

49 50 51  0 --  12849     51 -- number1: 51, number2: 12849, *pu: 12849

#include <SoftwareSerial.h>

SoftwareSerial MyBlue (0, 1);

unsigned long number2 = 0;
uint8_t *p = (uint8_t *)&number2;
uint16_t *pNumber2 = (uint16_t *)&number2;
char buffer[512];

void setup () {
    Serial.begin (9600);
    MyBlue.begin (9600);
}


void loop () {
    if (Serial.available()) {
        uint8_t number1;
        Serial.readBytes (p, 3);

        sprintf (buffer, " %2d %2d %2d %2d -- ", p[0], p[1], p[2], p[3]);
        Serial.print (buffer);

        // store number, 8bits
        number1 = p[2];
        // clear high order 16 bits -- now number2 is just the low order 16bits
        p[2] = p[3] = 0;

        sprintf (buffer, "%6ld %6d -- ", number2, number1);
        Serial.print (buffer);

        sprintf (buffer, "number1: %hu, number2: %lu, *pu: %u", (uint16_t)number1, number2, *pNumber2);
        Serial.println (buffer);
    }
}
6

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