Advice on LCD display for Picaxe project.

[HellasTechn]

Ok now that i dont get. C.2 only pulses from 0V to 1.5V when i connect it with the BC558 base.

It is probably because of the 558. I noticed that when i remove the wire from base to C.2 and use Oscope probe to transistors base i measure 1.5V and the backlight turns on really dimm.

i guess i need a different PNP transistor.

 

[HellasTechn]

Back to the main problem, After downloading the code to the slave 20m2 and useing the following code to the master 20m2 i get to lit the 2nd line of the LCD (all pixels) and line 1 is off.
What are we missing here ?

Main:
Serout b.1, N2400_4, (254,1) 'Clear display and move to the start of the first line.
pause 30
Serout b.1, N2400_4, (255,%000) 'Turn backlight on.
pause 20
Serout b.1, N2400_4,("HELLO") 'Print HELLO.
wait 10
Serout b.1, N2400_4, (255,%100) 'Turn backlight off.
wait 1
goto main

 

[CDRIVE]

Like I said PNP's must be wired like this.
Chris

 

[HellasTechn]

I have tried wiring the transistor this way and made no difference.

 

[CDRIVE]

Disconnect R1 from Pin C.2, then ground it. Does the back light turn on?
If it does then leave it disconnected from Pin C.2 and scope C.2 again.

Chris

 

[CDRIVE]

I forgot to mention that if grounding R1 doesn't turn the back light on then T1 went west or the LCD's "A" pin isn't connected to the 5V rail. On that note if you eliminate the PNP altogether and connect "A" to +5V and "K" to GND the back light should light.

Does the LCD have an integral limiting resistor on the board? If not make sure you add one before trying this. This is assuming the back light is an LED.

Chris

 

[HellasTechn]

I have checked all that before and found nothing wrong but i will check again later today and let you know.

After scoping disconnected C.2 it was found always low. When connected to the base of T1 through R1 it pulses from 0V to 1.3V, that is why i suspect that bc558 was not a good choice.

The LED works fine when connected directly to VCC and GND. also the BC558 appears to be in working condition.

That does not explain why the code does not work though but lets take one step at a time .

 

[CDRIVE]

You can post the lines of code that brings C.2 high. It should be something like ...

High C.2

You do realize you may have fried that port when you forgot the base resistor.

Chris

Oops, never mind about the code. I forgot it was serial controlled from the master chip.

 

[HellasTechn]

You do realize you may have fried that port when you forgot the base resistor.

Yes but luckily it still works fine

I think that most probably the reason it does not work is that the code is not compatible with the chip that controls the LCD.

 

[CDRIVE]

Yes but luckily it still works fine

I think that most probably the reason it does not work is that the code is not compatible with the chip that controls the LCD.

That's unlikely because it doesn't throw any errors in PE6. I haven't seen your modified schematic using the 20M2 in place of the 18M2. Did I miss it?

Chris

 

[CDRIVE]

I also have some trouble understanding the connection diagram here:
http://www.picaxe.com/docs/axe133.pdf
page 5.

I understand that H3 is "spare" but H2 pin C.5 where do i connect that ?
Also what is CON1 connevted to ?

I went back and read through more of your posts. All good questions and I confess I've been very distracted over here. I've been deeply engrossed in getting my feet wet in the latest release of the Great Cow Basic IDE. At the same time we have elections coming up in a week and I've been distracted with this too. There's an amendment 1 on the ballot that pertains only to my state of Florida. Researching it consumed much of my time and now I'm spending considerable time emailing and phoning everyone I know to pass along what a Yes or No vote really means.

All that said I don't believe for a nanosecond that the 20M2 can't do all of what an 18M2 can do and then some.

Chris

 

[Bluejets]

Have you considered looking at Arduino as a means to control your LCD?
Think you will find it is much easier both to implement and understand.
Use of clone boards keeps the cost at a minimum also.

 

[HellasTechn]

Have you considered looking at Arduino as a means to control your LCD?

Actually i have not because at the moment i am learning Picaxe. It is not a bad idea for the future though.

 

[HellasTechn]

All that said I don't believe for a nanosecond that the 20M2 can't do all of what an 18M2 can do and then some.

This is not what i meant. On the LCD there are two chips that contain the character database and more. I think that the axe033 uses different libraries and that may explain why i can not use the axe033 code with this LCD module.
That is just a guess though.

I haven't seen your modified schematic using the 20M2 in place of the 18M2. Did I miss it?

No, i haven't made one yet. I used the pins exactly as described in the PDF diagram.
B.1 on 18M2 replaced with B.1 on 20M2 etc.

P.S.
As for the rest of your post, most of it i do not understand and that is due to my poor skill in english but from what i understand there must be tons of work waiting for you.

 

[CDRIVE]

Constantine, your English is a hell of a lot better than my Greek.

Is this the serial LCD you purchased?
http://www.ebay.com/itm/IIC-I2C-TWI...k=3&rkt=18&sd=310565065933&afsrc=1&rmvSB=true

Chris

 

[HellasTechn]

Constantine, your English is a hell of a lot better than my Greek.

Well sir that is not your fault though. Noone taught you Greek ! On the other hand i was taught english at school because it would "make my life easyer"

Is this the serial LCD you purchased?
http://www.ebay.com/itm/IIC-I2C-TWI...k=3&rkt=18&sd=310565065933&afsrc=1&rmvSB=true

Yes that is the one.

 

[CDRIVE]

Well that is not your fault though. Noone taught you Greek ! On the other hand i was taught english at school because it would "make my life easyer"



Yes that is the one.

There's a very old expression used here in the U.S. when someone doesn't understand what they heard or read. The expression is "It's all Greek to me". This isn't going to mean a thing to you because you're Greek!

OK back to your problem. Let's try and trouble shoot this in an orderly manner by breaking your project into blocks. Unless I'm missing something your LCD is serial so it contains it's own I2C buss converter. It should be capable of inputting serial data between GND and a single input pin.

Let's try loosing the intermediate 20M2 and feed the LCD serial data directly from a single 20M2.

Main:
     serout 7,T2400,(“Hello”)
     wait 2
     serout 7,T2400,("World")
     wait 2
GoTo Main

Chris

 

[HellasTechn]

There's a very old expression used here in the U.S. when someone doesn't understand what they heard or read. The expression is "It's all Greek to me". This isn't going to mean a thing to you because you're Greek!

That's right ha ha ! You know we have a very similar expression here in Hellas (i prefere the name Hellas not Greece for many reasons ) and that is "it's all Chineese to me".

Let's try loosing the intermediate 20M2 and feed the LCD serial data directly from a single 20M2.

Not a bad idea at all. i will use this method on page 36 of this manual
http://www.picaxe.com/docs/picaxe_manual3.pdf

It requires a much more complex code though.

 

[CDRIVE]

No, there's no SerOut command in any of the code you posted. Just try the code I posted.

Chris

 

[HellasTechn]

Yes but serout command as written in your code can only work when useing a slave picaxe chip to drive the LCD.