ProxyLCD and graphical LCDs with HD44780 driver

Last time we wrote an HD44780 driver that takes GfxLCD compatible display and works with CharLCD package. This is nice because we can use big ILI9486 as a character display.

You may ask, why?
Because with ProxyLCD we can see a big output from Symfony ๐Ÿ™‚ And because we can ๐Ÿ™‚
Today we will focus on two bugs from a previous part and we will see if all chipsets can work with HD44780 driver.

Part 1


RemoteLCD Node on Raspberry Pi with ILI9325 – HD44780 simulation

We have a remote LCD Node that works on NodeMCU board. It has a 40×4 char LCD attached to it and displays text received via a network message. We also can use Raspberry Pi as a remote LCD. But all those LCDs are small. We need something bigger and we have it! This something is an ILI9325 graphical display. There is a huge difference between char and graphic but we can simulate char interface. Our GfxLCD library has an ability to display a text and with a little bit of tinkering, it should work :D.
This could bring nice results, imagine a dump from Symfony with multiline formatting thanks to the ProxyLCD project. Nice ๐Ÿ™‚


GfxLCD and drawing a text

Finally, something that is missingย from the start, the ability to write some text on display. In Doton we needed an ability to display numbers and we have done it via images. It was a partial solution but good enough. But we want more ๐Ÿ™‚

So this time fonts, text and another step in endless struggle with displaying anything anywhere ๐Ÿ™‚


GfxLCD – rotate SSD1306 and NJU6450

We can rotate both ILI displays but NJU and SSD are awaiting their turn. Let’s give them some attention and add rotation to them.
This will close another task on endless list of improvements ๐Ÿ™‚
From what I see we should change drawing functions (recalculate coordinates) and flushing buffer should stay the same because it works directly on hardware.


GfxLCD tests and fixes – page drawing

We need tests for GfxLCD and we need it now! But this is a driver so what can we test? W can and must test all drawing functions. We have two algorithms the page and the area. Let’ begin with page one.
We can mock a chip class in such way that it won’t use a driver and all drawing would go to a buffer and we always can check if buffer looks as we want.


Daj siฤ™ poznaฤ‡ / Get noticed – summary

Time is almost over but we have so much more work to do! Of course, we won’t stop our work but let’s summarise was has been done during competition.

The main goal was to build a control node that can gather and display information from different sources/sensors. This node is the Doton project.

But before we could create it we have to do two other projects: a GfxLCD python library, NodeOne sensor and improve one: NodeMCU boilerplate. So, in fact, we have done four projects ๐Ÿ™‚


Raspberry PI, GfxLCD and ILI9486

Recently I bought an LCD 4″ IPS with an ILI9486 chip from Waveshare. It should be better than 2.8″ ๐Ÿ™‚ In instruction states that this display can work as system screen and I thought that maybe we can use PyQt or something instead of a custom driver.
The idea died quickly. I tried to run it on Raspberry Pi Zero W and this is not trivial ๐Ÿ™‚ First, I hit the bug with inability to use GPIO #17 and driver couldn’t be loaded. After some googling, I know that this is caused by the newest kernel. So I reverted to old one and… screen booted up but WiFi and Bluetooth did not.
So this way is no go. Back to the original idea and custom driver for ILI9486.