Serial LCD Controller

10 October 2009

I discovered a flaw in the current design that will only allow the controller to work with a connection to the computer and not to a microcontroller. I've updated the schematic below and will fix the controller design. I've added a project file below that also includes the fixed schematic.

If you look at the schematic you will notice that when you set the jumper to non-inverted so you can connect to a microcontroller for serial control it will not work. The reason is in the way I designed the circuit for both inverted/non-inverted RS232 control. Looking at the transistor in the circuit, the collector is held high through a 10K resistor. The collector feeds to the Rx pin on the PIC. When you set the jumper to non-inverted and attempt to send data to the PIC it won't work because the line is always tied high through R8 to 5V.

There is a fix and I have included it in the archive file below. There are two ways to do this:

1. If your board is already built and your intentions are to only use this LCD in a finished design and not attached to the computer then, snip the connection from R8 to 5V and the controller will only work in the non-inverted configuration.

2. Look at the included schematic in the archive and add the shown J2 jumper to your design which will allow you to select between the two types of communication.

04 October 2009

I have redesigned the LCD Controller and updated the code. The new schematics and code can be found below. I ported the code from MBasic to PicBasic Pro. I'll leave the old code up for those who still want it.

The files below are from a project that I have been working on for a serial LCD controller for a 4x20 line parallel display with the Hitachi chipset. I am also working on a USB design. In the picture of the demo board there is a wire jumper installed. This is because I screwed the pooch and somehow missed a crossed trace. I had to repair the board. In the download files the PCB files have been fixed. I'll upload some video of functionality when I get a chance.

The code and project files have been posted in the download links.

Project file downloads

Old code:

Power regulation board schematic

LCD and power board PCB

LCD schematic

LCD code

Demo application with sourcecode

05 October 2009 Project Files

PicBasic Pro PIC16F628A code for 16x2 character LCD

PicBasic Pro PIC16F628 code for 16x2 character LCD

PicBasic Pro PIC16F628A code for 20x4 character LCD

Archive containing test application, schematic, and PCB (ExpressPCB)

PicBasic Pro LCD Controller interface to Parallax GPS receiver

Ensure all the files are unzipped to the same folder. The include file that is referenced contains the fuse settings for the selected PIC chip.

I will be uploading a version soon that allows the type of LCD to be set. This will allow the same controller to be used for a variety of LCDs. I can't squeeze that functionality into a PIC16F628 chip without removing some of the current functionality. So, I am porting that over to a PIC16F88.

More to come...


Breadboard testing of the LCD controller



Software application for testing functionality



LCD controller schematic


A better view of the controller schematic can be downloaded from the link below:
http://picasaweb.google.com/lh/photo/LZac_OpDpd0lbB8jCWJL0Q

USB version of the LCD controller

A better view of the controller schematic can be downloaded from the link below:
http://picasaweb.google.com/lh/photo/_XtaXjprlNdzRaFHGrha_Q


Optional power supply schematic

A better view of the controller schematic can be downloaded from the link below:
http://picasaweb.google.com/lh/photo/Hp0EJqKk4PNbVm69Vd1p8g

 

Component layout


PCB with two controllers and the optional power supply


PCB bottom side

 

PCB top side




LCD prototype board component view




Prototype board attached to the back of a LCD




Netlist

Serial LCD Controller v1.4

----------------------------

C1 0.1uf
D1 1N4148
J1 16-pin Header
J2 4-pin Header, Right Angle
J3 3-pin Header
J4 6-pin Header. Right Angle
JP1 Shorting Jumper
Q1 2N2222
Q2 2N2222
R1 1M
R2 10k
R3 1k
R4 22k
R5 15
R6 10k Potentiometer
R7 1k
R8 10k
U1 PIC16F628
X1 20Mhz
HD44780 20x4 LCD Module Display

Netlist


USB BUS Powered LCD Controller
-------------------------------

C1 0.1uF
C2 10nF
C3 10uF
C4 0.1uF
C5 0.1uf
D1 1N4148
F1 500mA, Ferrite Bead
J1 USB Type B, Digikey 787780-1-ND
J2 ICSP, 6-Pin, Right Angle Header
J3 LCD Connector, 16-Pin Header
J5 2-Pin Header
J6 2-Pin Header
JP2 Shorting Jumper
JP3 Shorting Jumper
LED1 RED
LED2 GREEN
Q1 2N2222
R1 330
R2 330
R3 1M
R4 10k
R5 15
R6 1k
R7 10k
SW1 Power, SPDT
U1 FT232RL
U2 PIC16F628
X1 20Mhz

NOTE All resistors on the controller board are 1/8 watt

Netlist

5V Power Regulation v1.0
-------------------------

C1 10uf
C2 0.1uf
C3 10uf
D1 1N4004
D3 1N4004
J1 Power Jack
J2 3-pin header
LED1 Light Emitting Diode
R1 220
SW1 SPDT Slide Switch
VR1 LM7805

NOTE All resistors on the power board are 1/4 watt


You can do a search on eBay for the LCDs and you will find them listed for as cheap as $5.00 minus shipping.

04 October 2009 - Redesigned Controller

I have redesigned the controller to use some surface mount components. This is still a prototype and the final version will have all surface mount components and be a bit smaller. I also ported the code from MBasic to PicBasic Pro. MBasic is a great program but the makers have not updated it to include newer PICs. As such, I’ve been using PicBasic Pro which is a really nice basic compiler. The code size and speed rivals that of some PIC-C compilers.

Schematic

Newest Schematic with fix for connection to PC or microcontroller

Better view of the schematic can be downloaded at the following link: http://picasaweb.google.com/lh/photo/0gbrdTCrjH6KJyib-i33EQ?feat=directlink

Old schematic with flaw. Recommend not to build from this schematic

Better view of the schematic can be downloaded at the following link: http://picasaweb.google.com/lh/photo/Yi30Oi9tf_1AIOc2Z4cDGw?feat=directlink

Better view of the schematic can be downloaded at the following link: http://picasaweb.google.com/lh/photo/ySbtGz3Fb4xDZ26780GD8w?feat=directlink




Netlist:

Hobbybotics LCD Controller V2.3
Component Description Part Number Vendor Cost
C1 0.1uf, SMT 0805 80-C0805C104M5R Mouser $0.05
D1 1N4148, D0-35 512-1N4148T26A Mouser $0.03
J1 8-Pin Straight Header, Male 855-M20-9730846 Mouser $0.20
J2 6-Pin Receptacle, Female 649-68685-306LF Mouser $1.75
J3 6-Pin Receptacle, Female 649-68685-306LF Mouser $1.75
J4 6-Pin Polarized Header 571-6404546 Mouser $0.27
JP1 2-Pin Jumper 855-M22-1920005 Mouser $0.25
Q1 2N2222, SOT-23 512-MMBT2222AD87Z Mouser $0.06
Q2 2N2222, SOT-23 512-MMBT2222AD87Z Mouser $0.06
R1 1M, 0805, 1/8W 71-CRCW0805J-1M-E3 Mouser $0.07
R2 10k, 0805, 1/8W 71-CRCW0805-10K-E3 Mouser $0.05
R3 1k, 0805, 1/8W 660-RK73B2ATTDD102J Mouser $0.06
R4 22k, 0805, 1/8W 71-CRCW0805-22K-E3 Mouser $0.05
R5 15, 0805, 1/8W 71-CRCW0805-15-E3 Mouser $0.05
R6 10k, Potentiometer 72-T70YE-10K Mouser $0.74
R7 1k, 0805, 1/8W 660-RK73B2ATTDD102J Mouser $0.06
R8 10k, 0805, 1/8W 71-CRCW0805-10K-E3 Mouser $0.05
SW1 DIP-2 Switch 611-SDA02H1BD Mouser $0.56
U1 PIC16F628A, SOIC-18 579-PIC16F628A-I/SO Mouser $2.14
X1 20Mhz Resonator 815-AWCR-20.00MD Mouser $0.32
HD44780 20X4 LCD RT204-1 Ebay $10.80
PCB Printed Circuit Board HBLCD-V2.2 ExpressPCB $14.14




Total




$33.51

wow…very impressive work

wow…very impressive work and those pcbs look clean. Did you get those professionally done or are you making them yourself?

Did the cost to build include the pcb work?

 

Simulator

I downloaded the software in hopes that it would let me simulate the new eyes for Walter. Or actually the WAL9000. But it does not simulate. You really need the hardware.

So Curtis, what is the prominent large display area in the user interface for then? Does it show an “programme” of sorts. Could you share a screenshot of the app at work?

Rik

These boards were
These boards were professionally made. The project cost does include the cost of the boards. Hey, I belong to the church of the flying spaghetti monster also. Are u a pastafarian?

The large display area is so

The large display area is so that you can position the cursor to any cell on the LCD. That portion of the application was written to test that functionality. The area at the bottom right of the software is where you can define and create custom characters to send to the display or store in the LCD CGRAM. I am going to edit the post today after work with the easy to implement command set and an explanation of the software. In fact, I will rewrite the software so that you guys can create the simulations for the eyes. This is very easy to do and it will not take much for me to do. I was already pondering doing software for LCD graphics. I will post a screen of the software working. Maybe I can use that as an opportunity to do some video.

This project is designed so that others can take the PIC source and roll their own displays.

More to come when I get off work…

Do you happen to have info

Do you happen to have info on the mfgr of the boards that you could share? The most promising one I’ve found was the one that sparkfun uses, by the the turnaround time is lengly… :confused:

I sure am a Pastafarian, I pay homage to his noodlyness weekly with random pasta dinner sacrifices. :slight_smile:

 

The boards are done by

The boards are done by ExpressPCB. I design the board and purchase through their board service. Once I am satisfied with the design i purchase my board files from them for $60.00 so that I can send to a board house for mass production. I am really satisfied with their service as it takes about 3 days to get very high quality boards. The software is very simple but excellent. The website is www.expresspcb.com. I have a link to the board house that SparkFun uses for their board service and it is a great deal. You can bypass the middleman and save some money. I’ll have to post the link in the morning when I get to work as I don’t have it handy.

On a side note, don’t allow yourself to be tempted by the anti-pasta

Not able to compile the .BAS source!!

Hi Curtis Brooks!!

 

First of all!! This is a brilliant design!!

I’ve made the hardware for this!! But!! I’ve got problems compiling the “SerialLCD_REV21.bas” source for the PIC16F628!!

I’m using the Micro Code Studio!! Compiler Version - “PICBASIC PRO2.47”!! When I compile the source!! I get the following errors!!

FATAL ERROR: Too many errors. (21)
ERROR Line 141: Redefiniton of LABEL LCDWRITE. (SerialLCD_REV21.bas)
ERROR Line 176: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 193: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 260: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 282: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 323: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 332: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 356: Redefiniton of LABEL ElseIf. (SerialLCD_REV21.bas)
ERROR Line 384: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 387: Redefiniton of LABEL ElseIf. (SerialLCD_REV21.bas)
ERROR Line 388: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 391: Redefiniton of LABEL ElseIf. (SerialLCD_REV21.bas)
ERROR Line 392: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 395: Redefiniton of LABEL ElseIf. (SerialLCD_REV21.bas)
ERROR Line 396: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 399: Redefiniton of LABEL ElseIf. (SerialLCD_REV21.bas)
ERROR Line 400: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 404: Bad expression. (SerialLCD_REV21.bas)
ERROR Line 427: Redefiniton of LABEL LCDWRITE. (SerialLCD_REV21.bas)
ERROR Line 441: Redefiniton of LABEL LCDWRITE. (SerialLCD_REV21.bas)
ERROR Line 479: Redefiniton of LABEL LCDWRITE. (SerialLCD_REV21.bas)

I’m not sure!! why these errors occur!! Am I using the right compiler? (I guess it must be MBasic?? Is it free? there is no link to download!!) Please advice!!

Can you please provide a download link for the MBasic Compiler!! Or Can you please send me the .hex!! so that I can program the microcontroller directly!!

Thanks and Regards,

elektor_1234

I just wanted to say,

I just wanted to say, daaaaaamn!

Those are some sexy looking PCB’s! I’m just curious, has anyone done this with Atmega chips? I’ve got like, 3 extra 168’s laying around… would be awesome to make a serial backpack for it myself!

 

You’ve got some damn good walkthroughs, hopefully you’ll post more in the near future! :slight_smile:

Well, the posted basic code
Well, the posted basic code was written for MBasic and not PicBasic Pro. However, I have ported it over to PicBasic Pro and redesigned the boards. I also put together some documentation on how to use it. Let me get them posted in a sec.

Thanks for the kind words.

Thanks for the kind words. I’ve never worked with any of the newer Atmega chips although I have been getting the itch lately as I really like the free C compiler options. I’ll have to look into that.

Here is the download link to
Here is the download link to the Hex file for REV21: http://www.box.net/shared/gk56np1oc5. I’ll be posting the updated PicBasic Pro code soon. Now, the PicBasic Pro code was written in version 2.60 so, I’m not sure if you will have any issues with the 2.47 version. I’ll update the links above as soon as I package it all together.

Not able to compile the .BAS source!!

Hi Curtis Brooks!!

 

Thanks!! I don’t see any document!! Is it a .doc??!! Can you please let me know the link!!

 

Thanks and Regards,

elektor_1234

Not able to compile the .BAS source!!

Hi Curtis Brooks!!

 

Thanks for the .HEX file!! I’ll program my PIC with this!!

It’s great to know that you’ll be updating it for the PicBasic Pro too!!

Looking forward to the PicBasic Pro code!!

Great work!!

Thanks and Regards,

elektor_1234

Support for a 2 X 16 LCD!! Help needed!!

Hi Curtis Brooks!!

Can you please let me know if you can modify the code for me to support a 2X16 LCD!! Please advice!!

I’m using a 2X16 in one of my current home projects!!

Thanks and Regards,

elektor_1234

Rev21 will support a 2x20

Rev21 will support a 2x20 LCD. I’ll add the ability to select what type of LCD you are using so it can be used with 2x16, 4x20, 2x20 and 4x40 LCDs. This way you’ll be able to select the type you are using without compiling code for different backpacks.

**I haven’t uploaded it yet. **
I haven’t uploaded it yet. I need to add a few commands. Look for it to be up some time today.

Thankyou for the interest in
Thankyou for the interest in it. I usually see around 20 to 30 downloads a day but no one ever lets me know how it worked for them. So, will you let me know how it works out for you? I’ll be putting the newest version up today also.

I’ll check it later the day!!

Hi Curtis Brooks!!

Thanks!! I’ll check for it sometime later today!! and Will let you know!!

Thanks and Regards,

elektor_1234

Will definitely let you know!!

Hi Curtis Brooks!!

Thanks!! You’re doing a great job over there!!

I’ll definitely test this and let you know my results!!

Thanks and Regards,

elektor_1234