cfag12864b LCD Driver Documentation¶
- License
GPLv2
- Author & Maintainer
Miguel Ojeda <ojeda@kernel.org>
- Date
2006-10-27
1. Driver Information¶
This driver supports a cfag12864b LCD.
2. Device Information¶
- Manufacturer
Crystalfontz
- Device Name
Crystalfontz 12864b LCD Series
- Device Code
cfag12864b
- Webpage
- Device Webpage
- Type
LCD (Liquid Crystal Display)
- Width
128
- Height
64
- Colors
2 (B/N)
- Controller
ks0108
- Controllers
2
- Pages
8 each controller
- Addresses
64 each page
- Data size
1 byte each address
- Memory size
2 * 8 * 64 * 1 = 1024 bytes = 1 Kbyte
3. Wiring¶
The cfag12864b LCD Series don’t have official wiring.
The common wiring is done to the parallel port as shown:
Parallel Port cfag12864b
Name Pin# Pin# Name
Strobe ( 1)------------------------------(17) Enable
Data 0 ( 2)------------------------------( 4) Data 0
Data 1 ( 3)------------------------------( 5) Data 1
Data 2 ( 4)------------------------------( 6) Data 2
Data 3 ( 5)------------------------------( 7) Data 3
Data 4 ( 6)------------------------------( 8) Data 4
Data 5 ( 7)------------------------------( 9) Data 5
Data 6 ( 8)------------------------------(10) Data 6
Data 7 ( 9)------------------------------(11) Data 7
(10) [+5v]---( 1) Vdd
(11) [GND]---( 2) Ground
(12) [+5v]---(14) Reset
(13) [GND]---(15) Read / Write
Line (14)------------------------------(13) Controller Select 1
(15)
Init (16)------------------------------(12) Controller Select 2
Select (17)------------------------------(16) Data / Instruction
Ground (18)---[GND] [+5v]---(19) LED +
Ground (19)---[GND]
Ground (20)---[GND] E A Values:
Ground (21)---[GND] [GND]---[P1]---(18) Vee - R = Resistor = 22 ohm
Ground (22)---[GND] | - P1 = Preset = 10 Kohm
Ground (23)---[GND] ---- S ------( 3) V0 - P2 = Preset = 1 Kohm
Ground (24)---[GND] | |
Ground (25)---[GND] [GND]---[P2]---[R]---(20) LED -
4. Userspace Programming¶
The cfag12864bfb describes a framebuffer device (/dev/fbX).
It has a size of 1024 bytes = 1 Kbyte. Each bit represents one pixel. If the bit is high, the pixel will turn on. If the pixel is low, the pixel will turn off.
You can use the framebuffer as a file: fopen, fwrite, fclose… Although the LCD won’t get updated until the next refresh time arrives.
Also, you can mmap the framebuffer: open & mmap, munmap & close… which is the best option for most uses.
Check samples/auxdisplay/cfag12864b-example.c for a real working userspace complete program with usage examples.