LCD module clearance problem

[sbscott]

I have several of Peter Anderson's large LCD modules (#117) and they work well, and are low cost. I am having problems with cleariing the screen initially. Is anyone out there using these modules? Most of the commands seem to work except to clear the screen and place the cursor at the top.
The command to clear is "?f". I have tried this command in various ways but it just don't seem to work. I have read his webpage on their use but..

Thanks in advance.

 

[lanternfish]

Have just been reading the info for this LCD. Does the ?f command work if preceeded by either a ?c2 (cursor steady) or ?c3 (cursor blinking) command? I'm not sure if the LCD defaults to no cursor (?c0).
As other commands seem to work could you attach your code around the ?f command so that we can see if it is something prior to iut that is causing the problem?
Cheers

 

[BeanieBots]

I have no experience with those particular displays but have encountered many similar issues with others.

One thing to note is that LCDs continue to have some form of internal function with supplies as low as 0.8v. If your power supply has much capacitance on it, there can be enough volts to cause initial problems when powered up. Try shorting out the supply rails for a few seconds before powering up the board.

If it is a serial device which uses 'T' rather than 'N' convention, the first command may be missed if the serial line is not set to HIGH prior to sending the first command.

 

[Andrew Cowan]

I've used Phanderson's LCD modules before without problems.

It is good to add:
Put 'high (pin)' at the beginning of the code.
Wait a short while before sending the first command (4 seconds?)
Send all commands at T2400.

Are you using the 118 LCD?

A

 

[manie]

Just for info:
The Blue 20x4 LCD from Sure Electr. worked first time for me with screen clear etc.
Does the P Anderson lcd have a Hitachi HD controller ?

 

[Andrew Cowan]

It has a serial to parallel convertor, so it is a one wire device.

A

 

[sbscott]

It appears that putting the output pin high makes the difference. I LOVE easy fixes!

To all: I have ordered three of these modules over the past several months and have been using them in different activities. Anderson ships them with a 9600 baud serial controller that he gets from wulfden (http://wulfden.org/k107/index.shtml). What I like about these modules is that they are inexpensive ($34.95) and Anderson only charges actual shipping. I have had a problem with one of the LCD modules and he sent me a new one. I currently have a problem with one of the serial controllers, not sure what he will do about this. I may have shorted it out?

Thanks again folks. Your help, as always, is greatly appreciated. Not many folks out here in rural Colorado have heard of a PICAXE!

 

[Andrew Cowan]

Anderson ships them with a 9600 baud serial controller that he gets from wulfden.

I was under the impression that wulfden gets the chips from Anderson (and wulfden makes the boards).

But I do agree that it is a great way of controlling an LCD - very effective and easy.


A

 

[sbscott]

You are probably right about that. All I know is that they easy to work with and at $34.95 for a 4X20 backlite LCD, a real value.

 

[KIGX]

sbscott:

I have the same setup as you do - Wulfden board, phanderson chip, blue 20X4 LCD, and I have a similar issue. My problem is only during the very first time I send commands to the LCD. What I do is send a ?f as the very first command, pause 500, and then send it again. Then, I can send a ?f with anything else I send to the LCD and everything works fine.

Not sure but it seems the very first thing you send to the LCD at least some of it gets missed. But if you then pause and do it again it seems to work fine from then on...

 

[pha555]

The idle state of the PICAXE pin driving my controller must be at a firm logic one for a period of time prior to sending the first data. This is true of any serial LCD controller.

High 0 ' Be sure Tx Pin is idle for some time
Pause 5000

SerOut 0, T2400, ("?f")

Best wishes.

Peter H Anderson

 

[KIGX]

pha555,

Well, that explains a lot and now I know what BB and the others were talkng about...

Thanks,

 

[sbscott]

As I mentioned, putting the output pin high as suggested, just before you send the serial command to clear the screen, works.