Driving the LCD - share your experience

I think that HD44780 is pretty standard, but - as you have written - driven mainly from small MCUs 

Here is some example of using from Raspberry Pi:

https://tutorials-raspberrypi.com/raspberry-pi-lcd-display-16x2-characters-display-hd44780/?utm_content=cmp-true

didn't tried it but looks as one would expect it to look...

Thanks! yeah, the thing is, the LCD from the kit doesn't use an HD44780, but the arduino forum posts i found mention it could be driven as if it was the HD44780. This LCD doesn't appear to be commonly used by hobbyists, so there isn't much out there on practical implementations of drivers for it

ok - sorry, I have only today got my kit so I didn't check the documentation yet.

AFAIK HD44780 is considered some sort of standard, with many compatible chipsets. Our LCD seems to be based on/compatible with RW1063 ("For full design functionality, please use this specification in conjunction with the RW1063 specification. (Provided Separately)") - but, according to the datasheet, this driver is 2x8 character max, so maybe some variation of it is installed.

RW1063  seems to have many interfaces: parallel 4b/8b, serial SPI and I2C, of which our module uses I2C

https://www.crystalfontz.com/controllers/datasheet-viewer.php?id=227

https://www.sparkfun.com/datasheets/LCD/HD44780.pdf

After quick checking, RW1063 parallel interface looks similar to HD44780, so there is a good chance it can be driven with I2C HD44780 Arduino library...

I haven't received the kit yet. How are you connecting the LCD. Are you using external pull-ups resistors? Can you get the actual I2C address using a I2C scanner?

I just opened the box, haven't connected anything yet, I've been working on the software side for the past few days waiting for the kit to arrive, and it just got here last night before i went to bed. I'll be trying the LCD in the next few days as i'm also busy with uni today and tomorrow

Well! I haven't tried it, but this library looks promising if you're going to program in Python.

charlcd · PyPI

Searching on the site comes up with this old thread:  Midas I2C LCDs 

Midas also have a github page. Not sure if relevant: https://github.com/orgs/midas-displays/repositories

I did a project, informally as part of the PiCasso design challenge, that used some I2C LCD displays. They were 2 rows of 16 and had the common Hitachi chip compatible registers. The datasheet was very messy, and muddled up the different variants in a really confusing way (the panel was available as either a I2C, SPI, or parallel build), so I had to do some experimenting to get the interface to work.

/challenges-projects/design-challenges/picasso/b/blog/posts/9-pieces-of-pi-slice-2-manifesto-for-art-electronic

That might give you some ideas, but be warned that the interface to your panel looks different to the one I had, so don't blindly copy what I did there.

One important aspect to be aware of is that the controller on the panel has an embedded microcontroller, but it runs very slowly, to minimise the power consumption, so you have to be careful to ensure that it can keep up with your much faster device. One of the registers has a status bit that can be polled to see if the last command is finished. That's the fastest way of talking to the panel, if you can read the registers. In the case of the panel I chose, the I2C interface was write-only, so I had to instead look at the timings given by the datasheet for the various commands and make sure I exceeded them. If you use a library, it's likely that it will make use of that register bit and would fail if the registers can't be read, but hopefully the panel you've been given will allow for reading back from the registers.

A second factor that may not be obvious, if you've not worked with the panels, is that the voltage for the LCD section has a separate pin to the logic supply for the controller. That's so that the contrast can be adjusted. The complication is, though, that internally the common voltage between the logic part and the segment drive part is normally the positive logic voltage, not the ground that you might expect. For the panel I used, the LCD supply (Vo) had to be about 6V, so ended up negative relative to the ground for good contrast (easy to achieve because the panel itself had a charge-pump generator on it). In the case of your panel, it looks like the LCD supply only needs to be about 4.5V, so your Vo will be approx 0.5V above ground and you can just use a pot between the logic supplies to supply it. Adjust it to the right sort of area initially with a meter, because if it's too far out the display will look blank rather than just having poor contrast.

I’ve tried this library with an Arduino mega and it works fine

https://github.com/JeffVi/Arduino-I2C-RW1063-0B-002

The Python charlcd doesn’t work for me without modifying. So I think I will try to adapt this to rpi next week

This one is even simpler.. github.com/.../cfah2004ac

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