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diff --git a/README.HD44780 b/README.HD44780 deleted file mode 100644 index 5fb762e..0000000 --- a/README.HD44780 +++ /dev/null @@ -1,124 +0,0 @@ -# -# $Id: README.HD44780,v 1.3 2001/03/14 15:14:59 reinelt Exp $ -# - -This is the README file for the HD44780 display driver for lcd4linux - -This driver supports all display modules based on the Hitachi HD44780 chip. -These displays are made by different manufactures, and come in various sizes. - -At least the following types are known to work: - -DataVision DV16244: 2 lines by 16 characters -Nan Ya NLC 08x2x06: 2 lines by 8 characters - -The displays are connected to the parallel board (see Wiring below), and are quite timing-critical. -There's no way to delay a usermode program under Linux for e.g. 40 usec, so we have to do -busy-waiting. This is done in a delay loop, which had to be calibrated (see Configuration below). -Since 0.98 there are two new delay loops, one based on the processor's TSC (Time Stamp Counter), -one based on gettimeofday(). lcd4linux decides automatically which one to use (it prefers the -TSC method, but falls back to gettimeofday() if neither the tsc flag nor the MHz value is set -in /proc/cpuinfo). - -The driver knows of two ways of controlling the parallel port: The (old, ugly and unportable) raw -programming of ports, and the new, cool, great ppdev() style. You decide which one to use by -specifying either a hexadecimal value or a device file with the 'Port' entry in the config file. - -Note that the old port programming only works with standard ports (0x3f8, 2f8,...), but not -with PCI parallel port cards. - -ppdev requires kernel 2.4. The configure script detects if you have the required include files, -and deactivates ppdev if they are not there. - -You should use ppdev whenever possible. Raw port access may be dropped someday. - - -The driver supports vertical, horizontal and split bars (two independent bars in one line), -all bar types can be used simultanously. As the displays only have 8 user-defined characters, -the needed characters to display all the bars must be reduced to 8. This is done by replacing -characters with similar ones. To reduce flicker, a character which is displayed at the moment, -will not be redefined, even if it's not used in this run. Only if the character compaction -fails, this characters will be redefined, too. - - -Configuration: - -The driver needs the following entries in lcd4linux.conf: - -Display: HD44780 - -Port: either the hexadecimal address of the parallel port (e.g. 0x378) - or a ppdev device (e.g. /dev/parports/0) - -Size: [columns]x[rows] e.g. "16x2" - - -#ifdef USE_OLD_UDELAY - -Delay: calibration of the delay loop, loops per microsecond - THIS IS NO LONGER NECESSARY! - -It is very important to use a correct delay value, otherwise you will get only junk on the -display. lcd4linux has a switch '-d' where it helps you to find the correct value. Run -'lcd4linux -d' several times on a otherwise idle machine, and use the maximum value. If you -encounter display problems, increase this value. But don't take it too big, lcd4linux will get -slow, and you're burning CPU cycles. - -The delay value is defined by your CPU model and clock frequency (it looks like it's your -'BogoMips' value divided by 2, because we use a similar delay loop than the kernel does). -Here are some examples: - -Pentium MMX, 133 MHz, 106 BogoMips: 54 -Pentium MMX, 166 MHz, 333 BogoMips: 166 -Celeron, 333 MHz, 333 BogoMips: 166 -Pentium III, 600 MHz, 600 BogoMips: 300 -AMD Athlon 1010 MHz, 2012 BogoMips: 505 - -#endif - - -Wiring: - -There are two basic wiring modes for HD44780-Displays: a 4 bit mode (used by lcdproc) and a -8 bit mode (used by most other packages). At the moment we only support the 8 bit mode, but -I'm working on the 4 bit mode, too. - -The main difference is that the 8 bit mode transfers one byte at a time, but the HD44780 needs -some control signals, so some of the parallel port control lines are used for this. The 4 bit -mode uses only 4 bits for data (so a byte has to be transferred in two cycles), but you can use -the other 4 bits for the control signals. - -Normally a HD44780-based display have 14 or 16 pins, where pins 15 and 16 are used for backlight. -Power (+5V) must be supplied via pins 1 and 2, be careful not to change polarity, you will -destroy your display! Pin 3 is used to control the contrast, you can either hardwire it to GND -(pin 1) or place a potentiometer (10k-20k) between pins 1 and 2, and connect pin 3 to the slider. - -Note that the data bits are called DB0..DB7 on the display, but DB1..DB8 on the parallel port! - -Here comes the wiring diagram for the 8 bit mode: - ---- Display --- --- DB25 --- --- comment --- -Name Pin Pin Name - -GND 1 18 GND GND of power supply, too! -+5V 2 - power supply only -LCD drive 3 - see above -RS 4 14 Auto Feed register select, 0=data, 1=command -R/W 5 18 GND hardwired to 0, write data only -Enable 6 1 Strobe toggled when data is valid -DB0 7 2 DB1 data bit 0 -DB1 8 3 DB2 data bit 1 -DB2 9 4 DB3 data bit 2 -DB3 10 5 DB4 data bit 3 -DB4 11 6 DB5 data bit 4 -DB5 12 7 DB6 data bit 5 -DB6 13 8 DB7 data bit 6 -DB7 14 9 DB8 data bit 7 -+5V 15 - power for backlight -GND 16 - power for backlight - 10-13 not connected - 15-17 not connected - 19-25 not connected - - -Wiring diagram for 4 bit mode: soon to come! |