Arduino Cookbook, 3rd Edition

ASCII and Extended Character Sets

ASCII stands for American Standard Code for Information Interchange. It is the most common way of representing letters and numbers on a computer. Each character is represented by a number—for example, the letter A has the numeric value 65, and the letter a has the numeric value 97 (lowercase letters have a value that is 32 greater than their uppercase versions).

Values below 32 are called control codes—they were defined as nonprinting characters to control early computer terminal devices. The most common control codes for Arduino applications are listed in Table G-1.

Common ASCII control codes

Decimal	Hex	Escape code	Description
0	0x0	'\0 '	Null character (used to terminate a C string)
9	0x9	'\t '	Tab
10	0xA	'\n'	New line
13	0xD	'\r '	Carriage return
27	0x1B		Escape

Table G-2 shows the decimal and hexadecimal values of the printable ASCII characters.

ASCII table

	Dec	Hex		Dec	Hex		Dec	Hex
Space	32	20	@	64	40	`	96	60
!	33	21	A	65	41	a	97	61
"	34	22	B	66	42	b	98	62
#	35	23	C	67	43	c	99	63
$	36	24	D	68	44	d	100	64
%	37	25	E	69	45	e	101	65
&	38	26	F	70	46	f	102	66
'	39	27	G	71	47	g	103	67
(	40	28	H	72	48	h	104	68
)	41	29	I	73	49	i	105	69
*	42	2A	J	74	4A	j	106	6A