Lcd driver board

Puuhaaja

Senior Member
#1
I decided to do my own design of popular Axe133 lcd driver board. Problem with Axe 133 is that it uses different pinout diagrams compared to those other lcds which you can bought/get everywhere. So I changed Axe133 pinout diagram to suit those other hd44780 lcds. I also made a plug and play adapter to lcd. By using it you don't need to solder driver board to lcd. That's good option if you have many lcds and you don't want make driverboard for every lcd. Any ideas or comments are wellcome!
 

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srnet

Senior Member
#2
Good stuff.

If you put the header pins (loosely) in a vice, you can tap the short ends of the pins flush with the plastic separator. Then the pins are long enough so that you can put the header in the holes with the plastic seperator on the component side of the PCB. Its then easy enough to solder the pins.
 

SAborn

Senior Member
#3
Nice work.

I do have a problem with the header pins soldered to the underside of a single sided board without plated through holes for strength, as in the past i find after a few LCD changes you tend to peel the tracks off the board.

I do my LCD boards in reverse and sandwich the chip between the LCD and back board as there is enough room when using header pins and header sockets.

I also fit the header socket to the back board because its female terminals are protected when the LCD is removed, and little chance of causing a short between header pins.
Also the LCD has plated through holes so it dont matter what side the solder is on it, its also cheaper for header pins than header sockets, so with several displays the cost is cheaper with header pins on the LCD's.

I also use a resistor (330R) between LCD pins and the picaxe, as a lcd can produce reasonable static, i know most people dont include them, but i feel its always a good practice to have a resistor on picaxe pins when using a lcd.
It can also help to make routing the tracks easier, with using the resistors as jumpers.

Its still good work on what you have done and thanks for sharing it.
 

Puuhaaja

Senior Member
#4
Thanks for your comment. I had forgotten that it's possible to move male header's plastic separator. Maybe about year ago I have struggled with that kind of thing. If I remember right there was a risk that header pin can easily drop out from plastic separator if you loosen it too much. Anyways sometimes it's better to do it still. I don't know if the ic socket is best for plug adapter but I think that compared to female header you don't need to push it as deep and there's more space for side direction. Using 330r resistor is new thing for me. Does this means that those resistor are used in pins d0-d7 or is there any other pins where they are used?

Maybe the next project in future would be similar board using forum member Inglewood Pete's code using Picaxe 20x2: http://www.picaxeforum.co.uk/showth...ace-with-High-Speed-Serial-i2c-and-Mapped-i2c

Nick12ab has also done good info when using paraller interface: http://www.picaxeforum.co.uk/showthread.php?23707
 

srnet

Senior Member
#5
If I remember right there was a risk that header pin can easily drop out from plastic separator if you loosen it too much
I guess, if you hit them with a 1kg lump hammer the pins might even end up on the floor.

A few gentle taps with a light hammer are not a problem however.


I don't know if the ic socket is best for plug adapter but I think that compared to female header you don't need to push it as deep and there's more space for side direction.
They are not, as IC sockets are really designed for the thin flat leads of ICs.

In this application I use the 0.1" header sockets designed for the job, but they are not as low profile as an IC socket.
 

marks

Senior Member
#6
Hi Puuhaaja,
Great work !
One thing i like about a driver board with header pins on it
you can push it into a breadboard and also use it as a project board for your experiments.

Not quite as bling as yours I also have an example of an 8 bit board and also 4bit board to build
with example code you can also try ! (as yours will also work on the axe132 Board)

starts at post#14 http://www.picaxeforum.co.uk/showthread.php?19474-Learning-to-Drive-an-LCD-DISPLAY/page2
 

Puuhaaja

Senior Member
#7
you can push it into a breadboard and also use it as a project board for your experiments. [/url]
Good idea! That's worth testing for example on a small project which is built on a breadboard. Only problem is the pinout numbers which can't be seen directly but using axe 133 datasheet it will be easy enough.

Not quite as bling as yours
I'm lucky because I have possibility to do my own boards. Anyways thread link you gave is teachful and I will check it better when I start to do similar project using 20x2 board. If I remember right you have done 20x2 project using 9600bps....So does this mean that it's 4 times faster that Axe 133 which is using n2400?? command?

Link to my board's pcb files: https://dl.dropboxusercontent.com/u/16735593/Lcd%20hd%2044780%20Driverboard.pcb
 
#8
If I remember right you have done 20x2 project using 9600bps....So does this mean that it's 4 times faster that Axe 133 which is using n2400?? command?
I'm not sure of what speed Marks' version could handle. However, with the 20X2's background hSerial and 64MHz clock speed, you can reliably handle 76800baud data interfacing to an LCD or OLED. Refer here.
 

Puuhaaja

Senior Member
#9
'#COM 7 'AXE027
#PICAXE 20X2
#Terminal 76800 'SerTxd default at 64MHz
That seems to be true. I don't know much about baud rates and bps so do you have any idea how much faster 76800baud data interfacing is compared to Axe133 which uses serout n2400 command.
Anyways. I will do sometimes my own version of Picaxe 20x2 lcd driver board and post it here. Is it ok if I post it also for your thread because it will be straight copy from your code and schematics.
 
#10
I don't know much about baud rates and bps so do you have any idea how much faster 76800baud data interfacing is compared to Axe133 which uses serout n2400 command.
First off, nice job!

It's 32 times faster... 76800 / 2400 = 32

If it's stable at the 76800baud rate then I believe it could be worth using in the right situation like sending relatively large amounts of data to a PC, or another 20X2 (which is the only Picaxe able to handle that speed I believe). At 64MHz the 20x2 would certainly execute the code very fast, therefore refreshing the data on the display faster but I can't think of an application where it would be needed in order to solve a problem. I personally use 9600 baud for most of my programs. I have no real reason why, it just seems like a good number for me. I'm sure one would not be able to tell the difference since there are only 80 possible bits needed to be seen on the display at one time. Someone please correct me if I'm wrong!

Kollinsb
 
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