Make a new larger font for Waveshare SPI e-Paper

    There are five fonts (font8, font12, font16, font20 and font24) provided for e-Paper. Some users just want to make their customized fonts or bigger font, but have no idea about how to do it.
    This Blog, I will tell you how the provided fonts works and how to make a new bigger font.

How do the fonts provided works?

To draw a character on dots matrix screen, it works like to draw many dots on screen and make it look like a character. Just like this: we draw every “pixel” to white （for visibility I set it Yellow）or black, and finally we get the character “T”.

As you can see, we set the paint area to 9(wide) x 20 (wide). White is 0 and black is 1, then we can get a set of binary value for every raw, convert them to HEX format, we can get the value as the fonts file. Note that one HEX value stand for 8bits, if the last bits are less than 8, we could extend it. We say it is scanning from left to right and top to bottom:

We take the font24 as example. The fonts we used are created by MCD Application Team. Its scanning way is from left to right and from top to bottom as well.

Make new font

In this way, we can make a larger font manually, or use tool. Like this one, as the software only supports Chinese, I don’t provide it. The character I made is 24 wide and 40 height.

The next step we need to add the font40.c to libraries. We name it Font40_Table[ ] and add the Font40 structure

Add it to heard file and don’t forget to update the max height/width font value

Then we could use it on the code.

Effect

Draw char function

Some users what to make fonts for special character or other language. The most information things which they should consider about is how to calling the values of fonts on functions and turn it to pixels drawing.

The fonts we make above is all ASCII characters, and they stored in arrays in order of ASCII table from 32 (space) to 127 (DEL).

ASCII	Character	ASCII	Character	ASCII	Character	ASCII	Character
0	NUT	32	(space)	64	@	96	、
1	SOH	33	!	65	A	97	a
2	STX	34	"	66	B	98	b
3	ETX	35	#	67	C	99	c
4	EOT	36	$	68	D	100	d
5	ENQ	37	%	69	E	101	e
6	ACK	38	&	70	F	102	f
7	BEL	39	,	71	G	103	g
8	BS	40	(	72	H	104	h
9	HT	41	)	73	I	105	i
10	LF	42	*	74	J	106	j
11	VT	43	+	75	K	107	k
12	FF	44	,	76	L	108	l
13	CR	45	-	77	M	109	m
14	SO	46	.	78	N	110	n
15	SI	47	/	79	O	111	o
16	DLE	48	0	80	P	112	p
17	DCI	49	1	81	Q	113	q
18	DC2	50	2	82	R	114	r
19	DC3	51	3	83	S	115	s
20	DC4	52	4	84	T	116	t
21	NAK	53	5	85	U	117	u
22	SYN	54	6	86	V	118	v
23	TB	55	7	87	W	119	w
24	CAN	56	8	88	X	120	x
25	EM	57	9	89	Y	121	y
26	SUB	58	:	90	Z	122	z
27	ESC	59	;	91	[	123	{
28	FS	60	<	92	/	124	|
29	GS	61	=	93	]	125	}
30	RS	62	>	94	^	126	`
31	US	63	?	95	_	127	DEL

    We can see, we get the offset value of the characters by minus character ‘ ‘ (space)* the numbers of HEX data per character.

    For example, if we want to draw a char A, we know that its ASCII value is 65 according to the above table. And in the fonts the first character is ‘ ‘ (space) which ASCII value is 32. We get the offset 33 (65-32). And we know that, the font40 wide 24 and height 40, we can get that 24x40 = 960 bits for every character, and because we save it in HEX format, so we can get that, for every character, it has 960/8 = 120 HEX values. With this we can get the address of first data of character “A” is 33 x 120 = 3960. So Font40_Table[3960] is the first HEX data of character “A”. That is how the function working with the fonts. 

    If you want to make a new fonts for other characters which are not inclued in the ASCII table, you need to change this function to get the right values.