cfag12864b LCD Driver Documentation¶
| License: | GPLv2 |
|---|---|
| Author & Maintainer: | |
| Miguel Ojeda Sandonis | |
| 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: | http://www.crystalfontz.com |
| Device Webpage: | http://www.crystalfontz.com/products/12864b/ |
| 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# NameStrobe ( 1)------------------------------(17) EnableData 0 ( 2)------------------------------( 4) Data 0Data 1 ( 3)------------------------------( 5) Data 1Data 2 ( 4)------------------------------( 6) Data 2Data 3 ( 5)------------------------------( 7) Data 3Data 4 ( 6)------------------------------( 8) Data 4Data 5 ( 7)------------------------------( 9) Data 5Data 6 ( 8)------------------------------(10) Data 6Data 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 2Select (17)------------------------------(16) Data / InstructionGround (18)---[GND] [+5v]---(19) LED +Ground (19)---[GND]Ground (20)---[GND] E A Values:Ground (21)---[GND] [GND]---[P1]---(18) Vee - R = Resistor = 22 ohmGround (22)---[GND] | - P1 = Preset = 10 KohmGround (23)---[GND] ---- S ------( 3) V0 - P2 = Preset = 1 KohmGround (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 willturn 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.cfor a real working userspace complete program with usage examples.