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Old 21st March 2013, 11:23 PM   #711
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Quote:
Originally Posted by chaparK View Post
Alright, I'll make Najda compatible with the Apple remote controller. It's just a question of code so no problem. Please give me some time until I get such a remote controller from a friend on a loan otherwise I'll just buy one, but you can expect soon a new menu item "Learn Apple" in the relevant section.

>>>Oh please don't - I don't subscribe to the Apple mania


So this is a note for you Steve I suggest you look at how your power supply is behaving when there's no load at all because keeping a dummy load is unaesthetic, don't you think?

>>> Agree, unaesthetic but it's like I am driving a Bentley and destroying the environment. I actually save lots of watt over my previous Dac and tube pre. So saving money now Downtime is not really an issue as I power off when not using, However, I ordered a Mouser 30W unit to try...

That's great Steve, happy to hear it's all going well. You must have been quite unlucky on getting a faulty sensor.

>>> Yeah bit of a bugger but these things keep our grey matter tip top!


I'll fix that, have no worry. Next Monday the latest. Cheers and sorry for that annoying bug. In the meantime you could work on a decent casing

>>> Great. Case - yes, only a matter of time as Najda works so well. Perhaps I wait until some expansion board dimension are published.
Measure twice, cut once


Last edited by Speedysteve7; 21st March 2013 at 11:26 PM.
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Old 22nd March 2013, 01:54 AM   #712
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Great news about the apple remote... I promise I don't have ANYthing to do with apple mania! This is the only bit of apple equipment I own and it will give me extra pleasure to use this beauty in a system not designed by apple.

My module suddenly developed a strange problem. The LCD screen is all jumbled. And only displays on the 1st line. (the 2nd is blank). You can only make out some characters sometimes. This happened while playing music and no adjustments were being made. Everything else is functioning perfectly.

So, i have tried the following.
1. replace display. no change.
2. check and then replace all LCD wiring. no change! grrr....
3. power down and up in all the combinations I can think of. no change...

I'm rather at a loss to know what to do! Any ideas?
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Old 22nd March 2013, 09:53 AM   #713
chaparK is offline chaparK  Luxembourg
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Hi James,

If you have already replaced the LCD and checked the wiring, then I can suggest you ship the board back to me. If it's faulty then I'll fix it or more probably replace it with a new unit. Please contact me on my email if you wish to go ahead.

Cheers,

Nick
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Old 22nd March 2013, 10:17 AM   #714
Shaun is offline Shaun  South Africa
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I suggest first try and reset the contrast level, on the chance that it may have been corrupted.
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Old 22nd March 2013, 11:28 AM   #715
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Originally Posted by chaparK View Post
Hi James,

If you have already replaced the LCD and checked the wiring, then I can suggest you ship the board back to me. If it's faulty then I'll fix it or more probably replace it with a new unit. Please contact me on my email if you wish to go ahead.

Cheers,

Nick
This maybe connected / may not.
I have the top line of pixels missing from the 2nd row on my display. Been like that from first use.
In the beginning it was a bit intermittent. Changing the contrast cured it for a while (doesn't sound like a wire loose) - now it does not, the top line is always missing.
I can read the 2nd row words ok for now.

I will check the solder joints and I have a 2nd display to try too (The one I really want to use), and let you know.
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Old 22nd March 2013, 01:20 PM   #716
chaparK is offline chaparK  Luxembourg
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A bit of background on how the display is working might help you to debug LCD issues.

Data is transmitted from the micro to the display via a 8-bit parallel bus. This bus contains the lines labelled DB0 to DB7 in the StartUp Guide, section I.4.
Najda documentation

Other lines R/W, E and R/S allow handshaking with the display controller.

It's important to understand that the micro doesn't 'draw' the characters that are displayed on screen. These characters are indeed contained in the memory of the display controller itself, and the micro just says 'take the character defined at this memory location and display it at this position'. This explains why different LCD screens might have different 'fonts', because the way these fonts look like is defined in the display controller.

So if there's a faulty pixel or a faulty line of pixel, then it's for sure that the display itself is faulty because the micro cannot address a single pixel or pixel line.

So as far as I can understand from your problem Steve, it's not related to Najda but rather to the LCD module - because the display receives the command, it just doesn't dispaly the data properly.

The Contrast input of the LCD is level sensitive. The easiest way to control contrast would be to connect a pot between GND, 5V and the LCD contrast input.
On Najda, contrast is controlled by the micro, and the pot is hence replaced by a PWM signal. Contrast is adjusted by varying the PWM duty cycle. Adusting contrast will not cure a faulty display, although one might think for a short while the opposite - but it's more of a placebo effect.
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Old 22nd March 2013, 02:18 PM   #717
Shaun is offline Shaun  South Africa
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I have noticed that when I am looking at the display with the contrast down, or at an angle for which the contrast is not optimised, parts of the displayed characters can appear dim or missing.

Also, it is possible for noise on the 5V supply to cause the display to go erratic; a poor connection can have the same effect, and so can a drooping supply... just some ideas to check out.
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Old 22nd March 2013, 04:07 PM   #718
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Quote:
Originally Posted by chaparK View Post
A bit of background on how the display is working might help you to debug LCD issues.

Data is transmitted from the micro to the display via a 8-bit parallel bus. This bus contains the lines labelled DB0 to DB7 in the StartUp Guide, section I.4.
Najda documentation

Other lines R/W, E and R/S allow handshaking with the display controller.

It's important to understand that the micro doesn't 'draw' the characters that are displayed on screen. These characters are indeed contained in the memory of the display controller itself, and the micro just says 'take the character defined at this memory location and display it at this position'. This explains why different LCD screens might have different 'fonts', because the way these fonts look like is defined in the display controller.

So if there's a faulty pixel or a faulty line of pixel, then it's for sure that the display itself is faulty because the micro cannot address a single pixel or pixel line.

So as far as I can understand from your problem Steve, it's not related to Najda but rather to the LCD module - because the display receives the command, it just doesn't dispaly the data properly.

The Contrast input of the LCD is level sensitive. The easiest way to control contrast would be to connect a pot between GND, 5V and the LCD contrast input.
On Najda, contrast is controlled by the micro, and the pot is hence replaced by a PWM signal. Contrast is adjusted by varying the PWM duty cycle. Adusting contrast will not cure a faulty display, although one might think for a short while the opposite - but it's more of a placebo effect.
Cool - display change it is - Take the damn thing back to Maplin and get a refund...
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Old 22nd March 2013, 04:08 PM   #719
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Quote:
Originally Posted by Shaun View Post
I have noticed that when I am looking at the display with the contrast down, or at an angle for which the contrast is not optimised, parts of the displayed characters can appear dim or missing.

Also, it is possible for noise on the 5V supply to cause the display to go erratic; a poor connection can have the same effect, and so can a drooping supply... just some ideas to check out.
Thx. I have the contrast on full and no top line of pixels.
I'll check the wiring out of course but it's not erratic - it's permanent.
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Old 22nd March 2013, 04:38 PM   #720
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by Shaun View Post
I have noticed that when I am looking at the display with the contrast down, or at an angle for which the contrast is not optimised, parts of the displayed characters can appear dim or missing.

Also, it is possible for noise on the 5V supply to cause the display to go erratic; a poor connection can have the same effect, and so can a drooping supply... just some ideas to check out.
Quote:
Originally Posted by Speedysteve7 View Post
Cool - display change it is - Take the damn thing back to Maplin and get a refund...
Quote:
Originally Posted by Speedysteve7 View Post
Thx. I have the contrast on full and no top line of pixels.
I'll check the wiring out of course but it's not erratic - it's permanent.
Alright, in my previous post I was making the assumption that contrast could be properly adjusted.

It could also be that the range is not sufficient to cover the various models of displays on the market. So I'll extend this range to see if it makes any improvement, how about that?

So currently you can adjust contrast in 10 steps. I've set the range so that all my LCDs have optimal contrast when contrast setting is mid-way. I have 2 green and 2 blue displays. I have another white on black that I haven't wired yet.

Collecting data could also help: how did you set contrast for your display?
Steve has the contrast set to max. How about other Najda users? Would be great if you could let me know.
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