Decent Blue 16x2 LCD - UK

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Cicero

Active Member
Hi everyone,

I'm looking for a decent blue 16x2 parallel HD44780 compatible LCD.

I've bought this one, https://uk.rs-online.com/web/p/lcd-monochrome-displays/5326385/ but its response time is sooo slow. Also, the timing characteristics dont quite work out it seems. I tried to push the update time as close to their spec for the E signal timings (ns), and the best I could get is usecs toggle times.

The main problem is the electro-optical response times, rise times and fall times are in the 200ms region...thats very noticeable.

If anyone knows of a good one they've used I'd appreciate it.
 
What are you trying to do?, LCD's don't have fast response times, and if they did you wouldn't be able to read them that fast anyway.
 
Nigel Goodwin said:
What are you trying to do?, LCD's don't have fast response times, and if they did you wouldn't be able to read them that fast anyway.
Click to expand...
Just a regular display for some equipment. I have a menu that a user can step through by clicking a button, if a user clicks the button reasonably fast, the lcd update can just be a blur. Similarly, if a user changes a pot for example (0-255) display, or 0-100% or something, then its a mashed up blur until he stops moving it.

I've used a few green 2x16 LCD's a few years back, and they've been pretty good. You could even do scrolling text to display a sentence for example. If I try that on this, it wont look good.
 
I would suggest your problem may be that you're updating the display far too quickly, there's no need to do that - stick some delays in there

Needless to say, the only difference with the colour is the colour of the backlight.

Failing that, try OLED displays instead:
 
I update it every 200ms, or when the user scrolls through the menu. Can't slow down the user, haha.

Oooh, the OLED's look good.

Do you buy from Rapidonline often?

Are they HD44780 compliant? Really don't want to have to rewrite code. (EDIT: yes they are, win!)
 
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Cicero said:
I update it every 200ms, or when the user scrolls through the menu. Can't slow down the user, haha.
Click to expand...

No need to update it that fast, you can't read that fast

Oooh, the OLED's look good.

Do you buy from Rapidonline often?
Click to expand...

No, I just googled

However, Rapid have a very good reputation.

Are they HD44780 compliant? Really don't want to have to rewrite code. (EDIT: yes they are, win!)
Click to expand...

I googled for 'HD44780 oled'
 
Hola Cicero,

I doubt any user would appreciate being forced to read that fast. One of my initial mistakes when updating a display showing temperature readings.
 
The ST7066U is not famous by speed...

Did these "green" (you have mentioned was faster) have the same controller?
 
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I use the same one but its 20x2 ( same outline ) The trick is to lower the contrast and LED current I run the LEDs at half the current... I use an 82 ohm..

The RAPID one has a better temp spec so will be a tad faster!!
 
Come on guys, 200ms is not quick. 5Hz...

Ian Rogers said:
I use the same one but its 20x2 ( same outline ) The trick is to lower the contrast and LED current I run the LEDs at half the current... I use an 82 ohm..

The RAPID one has a better temp spec so will be a tad faster!!
Click to expand...
I run the backlit LED on a 100ohm already. Woah, but I did play with the contrast and it sped it up significantly, so thanks for that! Only thing is trying to find that balance of not seeing the pixel block behind the character, and speed now.
 
It is usually to use pot to manage LCD contrast:
1. Each LCD is different.
2. Voltage drop from rest circuit. LCD usually work between 4.5 - 5.5V

However:
1. What commands you use may make a difference. Look at "Return home" for instance and compare with original HD44780.
2. What is delay between commands or even nibbles? Should be near to datasheet.
3. Do you use 4-bit or 8-bit interface?
 
4bit. And currently I update every 200ms (if there are changes), a full 16x2 in 3ms.

I tried to speed it up by reducing the E signal toggling, but 3ms (for the whole thing) is the quickest I could get it without it just not displaying a thing.
 
I stopped reading the busy flag, years ago. Did not found yet a reason in trying to write again immediately after. Less code and one pin just grounded.
 
Page 6 of the LCD datasheet actually mentioning KS0070B, while the web page info state ST7066U. These two are not the same, KS0070B is a bit faster. In any way, manufacturer may use any compatible controller and usually in the datasheet state for instance "KS0070B or similar".

However, for E toggling time seems to be the same: minimum time for E cycle time is 500ns and E pulse width is 200ns. You have mentioned 3ms? That is far out of spec.

I have no idea what could be a problem... I can only suspect LCD use some other more slower controller or there is some glitch in the sending data code.

Can you confirm E toggling with other LCD and the same code works under spec?
 
I meant the 3ms is to update all 16x2 characters. For actual E cycle time I could lower it into the usec range, I couldn't get anywhere near the 500ns and 200ns mark as per the datasheet.
 
I would return LCD back if it is necessary couple of us to actually toggle E cycle - that is far out of spec.

One additional question: do you use clear display command?
 
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