How to `Serial.print()` "full" hexadecimal bytes? - arduino

Question

I am programming Arduino and I am trying to Serial.print() bytes in hexadecimal format "the my way" (keep reading for more information).
That is, by using the following code
byte byte1 = 0xA2;
byte byte2 = 0x05;
byte byte3 = 0x00;
Serial.println(byte1, HEX);
Serial.println(byte2, HEX);
Serial.println(byte3, HEX);
I get the following output in the Serial Monitor:
A2
5
0
However I would like to output the following:
A2
05
00
In words, I would like to print the "full" hexadecimal value including 0s (05 instead of 0 and 00 instead of 0).
How can I make that?

Answer 1

Simple brute force method, is to write a routine as:
void p(char X) {
if (X < 16) {Serial.print("0");}
Serial.println(X, HEX);
}
And in the main code:
p(byte1); // etc.

Answer 2

sorry - not enough reputation to comment but found previous answer is not fully correct. Actually, the nice light way to code it should be :
void p(byte X) {
if (X < 10) {Serial.print("0");}
...
giving the code:
void p(byte X) {
if (X < 10) {Serial.print("0");}
Serial.println(X, HEX);
}
And in the main code:
p(byte1); // etc.
hope this helps

Answer 3

Use sprintf to print into a buffer (two chars per byte + null terminator):
byte byte1 = 0xA2;
byte byte2 = 0x05;
byte byte3 = 0x00;
char s[7];
sprintf(s, "%02x\n%02x\n%02x", byte1, byte2, byte3);
Serial.println(s);
Added new lines in between to get each on new line. About '%02x', the % means here comes formatting information, 0 means to pad with 0, 2 means pad input until 2 characters wide and x means give me this as hexadecimal.
For other formatting options see http://linux.die.net/man/3/sprintf

Answer 4

The lowest footprint in Memory, Code and runtime would be classic bit playing
byte b;
Serial.print(b>>4, HEX);
Serial.print(b&0x0F,HEX);
Which is working fine on any 8bit type. For any other mask also the first line to
Serial.print((b>>4)&0x0F, HEX);

Answer 5

Try this:
//Converts the upper nibble of a binary value to a hexadecimal ASCII byte.
//For example, btohexa_high(0xAE) will return 'A'.
unsigned char btohexa_high(unsigned char b)
{
b >>= 4;
return (b>0x9u) ? b+'A'-10:b+'0';
}
//Converts the lower nibble of a binary value to a hexadecimal ASCII byte.
// For example, btohexa_low(0xAE) will return 'E'.
unsigned char btohexa_low(unsigned char b)
{
b &= 0x0F;
return (b>9u) ? b+'A'-10:b+'0';
}
And in main code:
comand_mod=0xA1; //example variable
Serial.print(btohexa_high(comand_mod));
Serial.print(btohexa_low(comand_mod));

Answer 6

wow! 7 years ago and I felt here, my answer might be useful for you (hopefully not anymore) or others looking for the answers like me.
Use "Serial.write()" to send a hex byte over serial.
All Serial.print() eg. println, printf, sprint, print will "print" your value in ASCII.