Would anyone know where i can get the I2C 20x4 LCD with the interface included. ebay is one place but none seem to have more than 50. There are results in Google but not sure if they are reliable.
Would appreciate if anyone could help. Looking for something similar to this that uses the LiquidCrystal_I2C.h library.
If you leave out the '20x4' when you search for a source you should find a much greater selection available.
These I2C interface boards are not restricted to a specific display size (16x2, 20x4, etc), the LCD controllers are all the same and therefore the interface board cannot differentiate between them.
Don
Hi,
I usually get mine from China via eBay, you can get some good bargains and I always use the I2C type, only 2 signal wires, you can also buy the little I2C piggy-back board/module on it's own, that will work with most Hitachi based displays. You have to fined the I2C address but there's a bit of code to help you do that.
See my site: www.melsaunders.co.uk
Hope it helps, regards.
Mel.
Are you wanting to actually buy LOTS of them (more than 50) from a single vendor?
If so, is the reason for this to try to ensure that they are all the same in terms of i2c address and pin wiring?
Even if ordering from the same vendor this may not ensure that they are all identical.
Even if all the backpacks are the identical design and use the same components, you may end up with backpacks that have different i2c address as they may not use the same PCF8574 chip on all of them.
If you have a need to use more than a single LCD at a time, you will want to make sure that you pick a device that uses a backpack with a configurable i2c address. The one in your link does not allow configuring the i2c address.
Be careful in that some backpacks that do allow configuring the i2c address only allow it to be configured before the backpack is soldered the LCD since the jumpers to set the address on the side of the backpack PCB that faces the LCD pcb.
Another thing to look for is where the wires attach.
Most backpacks seem to put the i2c header/connector on the backpack the way it is shown in the photo in your link. Some will face it the other direction. I prefer it the other direction as that way it doesn't get in the way if you want to mount the LCD in a case.
Also some backpacks have more than a single header on them. This is nice if you need to connect more than a
single i2c device as you can run the cable to the LCD and then another cable from the LCD to your other i2c device.
On thing you might want to consider is using my hd44780 library.
It is really nice if you are using a single LCD device as it can auto locate the backpack i2c address and auto configure the pin mapping. This allows it to work with any backpack regardless of the i2c address or pin mapping, or backlight control. And since it does this runtime, you can even swap backpacks with a backpack that uses a different i2c address or pin mapping and the code will auto detect it after the next restart - all without having to recompile the code.
The hd44780 library can be installed using the IDE library manager.
You can read more about it here: GitHub - duinoWitchery/hd44780: Extensible hd44780 LCD library
It includes several features that are not available in any of the other lcd libraries.
One recent addition is the ability to do automatic line wrapping of long lines.
If you enable it, when the output reaches the end of the line, it will automatically, and more importantly, correctly, wrap to the next line on the display.
--- bill
One other thing to look for on the LCD backpacks is pullup resistors on the i2c signals.
Some have them and some don't. They are required for proper i2c operation.
While some AVR parts have internal pullups that can be enabled on the i2c signal pins, not all do and on the ones that do, the internal pullups are too weak. While it can can often work when using only the internal pullups, it can cause issues because they are simply not strong enough.
Depending on other h/w and your needs, you may or may not want or need the pullups on the backpacks.
This is just something you need to keep in mind.
--- bill
Well that is whole lot of thing that you've provided. So based on the replies you've posted, could you please suggest me the links or videos to where i can get these ? especially the hd44780 display and any tutorials related to it.
All i need is the one that i had shown on the link. I had ordered two and both seems to be the same, well look wise. i would need 100 qty of these and so the library i had used was easy to follow and moreover these were easy to find on ebay.
Hi,
Look on ebay lots from China and cheap, well will be for 100!! Or would you like us to order them for you?
Regards
Mel.
The ppl selling those are not very much conversation and bargain. Just buy what we have kinda attitude.