Sending 16bit to Raspberry

Projects Programming
1

Hi,

Im trying to send a uint16_t Value to a raspberry Pi over I2C using Python.

Im sending it like this:

void I2cBigWrite(uint16_t bigVal) {
  digitalWrite(P1LED, HIGH); // set the LED on
  bigVal = 1000;
  Wire.write (lowByte (bigVal));
  Wire.write (highByte (bigVal));
  digitalWrite(P1LED, LOW); // set the LED on
}

and receiving it like this:

 def readTacho1(self):     
            freq = i2cbus.read_word_data(dev_address, 0xE)
            print freq

Pretty simple.

But what I receive is 33768. The arduino is sending the lowByte first, then the highByte.

If I split the reading into two bytes:

 def readTacho1(self):
  
            freq1 = i2cbus.read_byte_data(dev_address, 0xE)
            freq2 = i2cbus.read_byte(dev_address)
           
            print "First Byte: " + str(freq1)
            print "Second Byte: " + str(freq2)

I get:
First Byte: 232
Second Byte: 232

It looks like it is only receiving the (first) lowByte.
....

Do I miss something? :o

2

Do I miss something?

The fact that if you want to send multiple bytes, you should put them in an array, and send the whole array in one call?