Question

I’m really new to C, and so a bit confused.

I am trying to convert an int16 to a byte[] array.

I have a int16 like -200, and I want to convert it into a byte[2] array, like the following example does.

Velocity = -200 = hex FF38 = [hex FF] [hex 38] = [255] [56]

I am taking the values and passing them to the serial port like below, but I need to pass the int16, and have a function convert it to the byte[] for me.

Serial.print(255,BYTE);
Serial.print(56,BYTE);

I found the following code, but couldn’t get it to work

Serial.print((velocity & 0xff00) >> 8, BYTE);
Serial.print(velocity & 0xff, BYTE);

Any suggestions?? Any help would be appreciated.

Answer 1

Your approach looks fine, but maybe you’re getting tripped up by an endianness issue?

Serial protocols may also be regarded as either little or big-endian at the bit- and/or byte-levels (which may differ). Many serial interfaces, such as the ubiquitous USB, are little-endian at the bit-level. Physical standards like RS-232, RS-422 and RS-485 are also typically used with UARTs that send the least significant bit first…

Your code sends the most significant byte first (“big-endian”).