This time is something different. On the journey between shops, I saw a wooden Christmas tree. I looked at it and then it hit me! Mount some LEDs, attach ESP and use PWMs and this should work! We should have a beautiful blinking tree, small but tree 😀
I’m on a project that requires some feedback after the operation is made. I cannot use an LCD because they are only two pins left and almost no memory. So my mind focused on two LEDs but after a while, I made a choice, I will use tricolour LED.
From what I read there are two types, one with a common anode and one with common cathode. We will go with common anode.
Module added to boilerplate
Last part was strange, we wrote a direct driver that has no real usage. We done it only because we kept compatibility. This time we will do something more useful, WiFi content driver. We will try and do in such way that only content is send. This is more friendly for network and sanity 😛
What does it mean? It means that we will add another driver to CharLCD. This will allow us to use remote LCD with Raspberry Pi and later with any application in Python. It should be possible to use it with LCD Manager package and this is something very interesting 🙂
As a remote LCD we will use HD44780 (40×4) hooked to NodeMCU via i2c (but we know that we can plug any LCD via gpio or i2c 😛 ) and it will listen to broadcast messages.
Rpi (with CharLCD and driver) will broadcast UDP messages into network.
Lets get started.
Time to take another step with NodeMCU and HD44780. This time we will separate driver logic from lcd logic. Why? Because it is much more flexible for our lcd (direct and bffered) to have general write, set_xy and move wiring specific logic to driver. This way we can just swap gpio with i2c without any problems.
This imply that we will also write i2c driver 🙂
Another matter is hooking screens with size 40×4. In fact they are two smaller lcds, 40×2, with shared all signals except E1 and E2. How it works? You set required signals and select top screen with E1 or bottom with E2.
Lets get to work.
Code is available in boilerplate
Our previous computer app was a failure. Happens from time to time:) Choosing wxPython was a huge mistake. Seems wx bindings are outdated.
After a long walk to cool of my head and think a little (but mostly catching pokemons) I recovered my strength and began second approach. This time I’m using PyQt5. It has Python3 bindings and lots of nice features, like ability to emit signals to other objects.
Spoiler: this time a full success 🙂
Get source from GitHub
We need something to see the state. I think the best way is to display icon in the taskbar. It must work under Windows 10 and Ubuntu/Mint.
To build GUI I will try and use wxPython. Sadly their bindings are for Python 2.7 not 3.x. I found wxPython Phoenix Project but for now lets stick with official release.
Spolier: we gonna fail – see running section. This is why code is dirty and nasty – no reason for refactor.
We have a small problem at the office. This problem is only one toilet. Additionally not all rooms can see it and know if it is busy or not. So quite often someone runs and slams into closed door.
Such runner has two options, form or join queue and wait or go back to desk and return later.
It would be much better for all of us if we could check toilet status from our desks.
How to do it? Simplest way is to detect if light is enabled. Hopefully this would be enough. If not I have another idea 🙂
As light detector I’m going to use lm393 light sensor and as the brain NodeMCU v3.
Our module displays strings as soon as function write is called. It is mostly enough but sometimes it is better to prepare what we want to display and then display it. Such action uses buffer and that why I’m calling this buffered mode.
We made something like this in CharLCD so we can convert idea to NodeMCU. Due to LUA characteristic both modes are combined into one module.
We played a little with lcd and we know that it works 🙂 It is a good idea to create a class that can be used in any project. Such class must allow setting width, height and pins if they are different from default one. It’s behaviour is based on lcd direct from CharLCD python class.
That means it is gonna display chars directly without buffer.