• lcd4wl Sourcecode
• kmod-lcd4wl_2430-brcm-1_mipsel.ipk

Usage:

To install the precompiled module download the ipk above and install it:

ipkg install kmod-lcd4wl_2430-brcm-1_mipsel.ipk

Then insert the module:

insmod lcd4wl

Using dmesg should show you what to do next.

mknod /dev/lcd c xxx 0
… where xxx is the major number of your device

After creating the device entry you can access your LCD with:

echo “Hello OpenWRT\n\rShow me if it’s working” > /dev/lcd

for writing to the LCD or

cat /dev/lcd

to read from the LCD.

Here the supported command:

• \n: Puts the cursor to the next line, on the same position
• \r: Sets Cursor to the start of the current line
• \i: Clear Display
• \h: Move Cursor home
• \dx: Set Display Status (x=0: off, x=1 on)
• \cx: set Cursor (x=0 off, x=1 on)
• \bx: set Blink (x=0 off, x=1 on)
• \xx: Display shift (x=0 off, x=1 on)
• \yx: Shift Direction (x=0 right, x=1 left)
• \ax: Cursor increment (x=0 off, x=1 on)
• \sx: Cursor shift (x=0 off, x=1 on)

So I conected the /CS line to the display’s Enable Pin. Moved R/W from A2 to A1 and adjusted my driver. I connected the display, loaded the module and …. nothing!

So I started my PC Scope Software, connected CH1 to /CS line and GND and … HARDWARE NOT FOUND. So I realized the fancy red led was dark and I checked the LPT-cable and the power connection. Hmm shouldn’t the red led on the power plug be on? Wow the transformer of the power plug din’t survive the night (btw. it was me going out not the power plug …). So I opened up a box and searched for a replacement power supply. Found an adjustable switching regulator and connected. The Software begann calibrating and reported: Calibration failed!

O.k. maybe the oscilloscope doesn’t like the switching power supply because of all this spikes and so…

But now back to topic: Why did the LCD stay blank… Maybe the bus interface is somehow to fast for that little display (but it worked with using 3 address lines). Is the Enable signaling correct? I will try using an inverter…

So I soldered a standard NPN inverted using a 2n3904 and 2 resistors connected everything, reloaded the kernel module and … nothing! Hmm it would be good having a working oscilloscope…

After that I think I’m gonna use the other solution…

Ext IF	#	LCD	#
D0	1	D0	7
D1	2	D1	8
D2	3	D2	9
D3	4	D3	10
D4	5	D4	11
D5	6	D5	12
D6	7	D6	13
D7	8	D7	14
A0	9	RS	4
A1	10	E	6
A2	11	RW	5
A3	12	–
+5V	13	VDD	2
/CS	14	–
/RD	15	–
/WR	16	–
/INT	17	–
GND	18	VSS	1
		Vo (contrast)	3

Vo … connect a 10k poti between VDD and GND and the wiper to Vo.

For a better bus interface I have to look on the function of the /CS line in more detail so that the LCD doesn’t get disturbed by misc. data.
To get some data onto the display I modified diag.c the kernel module that is used by OpenWRT to set the Router’s LEDs and to fetch some keys. diag.c can be found in: /location_where_you_unziped_openwrt/target/linux/packages/diag/src/. I added a own /proc entry called extif. And so I was able to display data that way:

echo “iHello OpenWRT ” > /proc/diag/extif

The “i” is only there to tell the module to initialize the display first.

My Module

Next step will be that i write a module on my own that handels everything –> Read here more about the module…