Guide Make your own USB LCD controller!

Hi everybody

Ages and ages ago, I posted this and many people said they'd like a guide. So here it is!

This is a guide for making an LCD that connects to your computer using USB, primarily intended to be external. You can see mine here. To make the board smaller, it doesn't have the GPOs.

This thread should also be used for suggestions on how to improve the circuit, add new features, and fix bugs in the firmware.

Schematic and layout
First of all, the schematic.

The PCB layout in colour.

And a 300dpi printable version.

Component list:
R1; R8; R9; R10: 10k
R2; R7: 4k7
C1; C2: 22pF
C3; C5: 100nF
C4: 220nF
C6: 100uF
Q1; Q6: BC184L
RV2: 4k7 preset
LCD1: HD44780/KS0066U compatible
X1: 4MHz
T5: USB B (bought from Farnell)
J2: ALPS 11mm rotary encoder (from RS, part 263-2930)
BUZ1: miniature buzzer
U1: PIC18F2550 DIP28

Note that I've used a transistor for the buzzer, so you can connect someting else there instead... mod on!

The connection to the rotary encoder works like this: (diagram)
Pin 2 on encoder goes to pin 1 on J2
Pin 3 on encoder goes to pin 2 on J2
Pin 5 on encoder goes to pin 3 on J2
Pins 1 and 4 on encoder go to pin 4 on J2

Firmware
Here.

Installing in Windows
XP/2000: Download this to your desktop and tell Windows to use that as a driver when it asks.
Vista 64-bit: see scorpia's post
I think Vista 32-bit works with the XP/2000 method, I'm not sure though.

This is the required programmer config (assuming 4MHz crystal). The USB voltage regulator is critical, as the PIC won't even try to start up without it.

Supported commands:
Position: 254 71 [col] [row]
Home: 254 72
Underline on: 254 74
Underline off: 254 75
Blink on: 254 83
Blink off: 254 84
Define custom: 254 78 [c] [8Bytes]
Clear display: 254 88
Backlight on: 254 66 [mins] (mins is just discarded)
Backlight off: 254 70
Backlight brightness: 254 152 [value]
GPO off: 254 86 [1-4]
GPO on: 254 87 [1-4]
Set GPO PWM: 254 102 [1-4] [0-100] (works as a percentage)
Buzzer off: 254 86 5
Buzzer on: 254 87 5

Computer software
This will work with LCDSmarite, if you set it to a Matrix Orbital serial LCD.

And finally... mine in action:


Any questions, feel free to ask!

ch424

 

Is this the one that works with 4x20 displays?

 

Anything up to 20x4, as long as they're HD44780 or KS0066U compliant. KS0066FF00 is incompatible.

It doesn't work with 40x4 displays.

ch424

 

Excellent!

Now I'll have to breadboard it since i have no etching tools.

Cheers ch424

 

This looks really handy but I really don't have the skills... but if some would like to make one extra I could suitably reimburse them for their time and effort

 

Pr0! You didn't route the datalines through the powersupplies.

 

I have a HD44780 unit that connects to parallel port. Is it possible to mod it so I can connect it to USB ?

thnx

 

what was the total cost of the parts that you got?

 

Yes, that's precicely what this circuit does - and more!

As for total cost... £10 plus the cost of the PCB (£3?) and an LCD (£16-£35?)

ch424

 

YEt another question for you CH424, can this be adapted for a T6963C LCD? Not a NxM display though, has 20pins...

 

hmm... what does it exactly do? do I need programmer to make that thing work?

 

Doug, no it can't, sorry.

Valo, have a look at the FAQ: http://forums.bit-tech.net/showthread.php?p=490773
This basically connects to your computer, and can show system info, temperatures, time/date, track/album/artist name from itunes/media player/winamp, control winamp, say when you have new emails, show RSS feeds - and more!

ch424

 

Rotary knob and the buzzer are used for what ?

 

Navigating menus, changing tracks, controling volume etc. You can set the buzzer to buzz under certain conditions: e.g. when you get an email or if your temps get too high.

ch424

 

Very nice mod guide, nice pictures and its clearly explained I might even give it a try, once I get a little funds for the parts of course....

 

Not really free: the price is that it takes 6 weeks for delivery. If you just pay £4 you can get one next day!

ch424

 

I'm Really tempted to do this as I have an lcd that ive never used in my parts bin. Just A link I thought might be usefull. Got it from TX297 on irc. Its a PIC programmer maded out of spare parts ( read: cheap) http://s95417013.onlinehome.us/ktekx/5.htm

Hope that helps everyone as much as it helped me.

Edit: Schematic for the programmer is here: http://www.olimex.com/dev/images/pic-pg1-sch.gif

 

Wow, that's brilliant! Thanks!

ch424

 

Excellent. I'd been thinking about having a crack at implementing what you've done for a while now. Good effort - I'll give it a go when I get back from my holidays

 

Excellent work ch424!!
Do you know if they make that PIC in a SMD package? I'd like to make it as small as possible....but then again, how could I upload the hex to a SMD PIC....?
This is just what I was looking for to try out on my 4x20 PLED