LCD display and buttons in Python (tutorial and code)

Hairybiker

I'm lazy as well, that's why I don't like too much typing

If I am re-using code then it goes into a procedure and is forgotten about

Given Python's strict layout issues, I find it is simpler to dump into a proc and just call it rather than paste/edit.
Been looking into MPD but there doesn't seem to be much you can read from it, no info like playing/left time etc.
Might be better reading it from the rune webpage and scraping the result.

XploD

Actually, there are lots of of commands for MPD. I'm using MPD Python library, here you find all the commands: http://pythonhosted.org/python-mpd2/topics/commands.html

On the same way I'm getting artist and title, I think it's possible to get all other (current time, total time, bitrate, filename, size etc etc) but I will implement my own counter for elapsed time which will be syncronized on each change (new track, play/stop/pause). So it will be reseted to zero on song change and on pressing stop. And while playing, it will count independently. Because, it's not very good for optimization to "spam" MPD every 1 second to get elapsed time from it.

Since my college semester is done, I moved to my parents house during summer and now I'm facing a small problem: I have only one ethernet cable in my room for connecting my laptop and Wi-Fi signal is very poor in my room so I'm not able to listen to internet radio and SSH and RuneUI are pretty slow due to this. I will have to get an ethernet switch or something to connect it via cable or get a Wi-Fi repeater.

Here is my current setup: http://i.imgur.com/qe1mlA8.jpg

Hairybiker

Cheap switch is the best way, unless all your stuff is wifi.

XploD

UPDATE

05.07.2015

- Fixed problems with buttons; MPD was closing connection after 60 seconds of inactivity -> fixed with pinging MPD every 50 seconds
- Added dynamic backlight control: don't know if it will be useful for somebody, but I had problems due to display lightning up my room so I wasn't able to sleep now the backlight will go off when you stop or pause playback, after specified time, you can enable/disable this and specify the time between pause/stop and going off

HOW TO UPDATE FROM LATEST VERSION BEFORE THIS

To update to this version from latest before this, you only have to get the newest RA_LCD_Buttons.py. You can do this with GUI (if you have Samba enabled or another app like WinSCP, links are here:

TAR Archive: http://buzzthisnow.com/RA_LCD_Buttons.tar (TAR archive)
RAR Archive: http://buzzthisnow.com/RA_LCD_Buttons.rar (RAR archive)

Or you can do it in terminal (via SSH). First, remove the old one. Position yourself where your RA_LCD_Buttons folder is and remove it with:

rm RA_LCD_Buttons

Then get a new one:

wget http://buzzthisnow.com/RA_LCD_Buttons.tar

And then use this command to extract it:

tar -xvf RA_LCD_Buttons.tar

Now you can delete the archive if you want, to free up some space, by executing:

rm RA_LCD_Buttons.tar

It will create a folder named RA_LCD_Buttons, execute this command to enter it:

cd RA_LCD_Buttons

Now you can start it with:

nohup python2 RA_LCD_Buttons.py >/dev/null 2>&1 &

HARDWARE MODIFICATION FOR BACKLIGHT

If you want to use this feature for dynamic LCD backlight, a hardware modification is needed. You will need a BD139 transistor and a 10 kilo ohm resistor. Or if you know what you're doing, you can use any other suitable transistor-resistor combination. I used this one. The schematic is attached in this post. Then in RA_LCD_Buttons.py you have to change LCD_BACKLIGHT pin according to where you connected it and you have to specify backlight_timeout. If you put it to 0, it will be disabled.

COMMENTS

I'm currently struggling with PWM. This thing with backlight is just a beggining, I'm working on creating a dimmable backlight: you would be able to adjust backlight brightness with your remote, and also turn it off with a key press instead of this automatic turn off when paused/stopped.

Attachments

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XploD

Hairybiker wroteOK
The i2c modules I have (currently several of them ) is this one:
ebay link

99p delivered or £2 if you want one from the UK. (on Amazon)

Program:
Link to source code for i2c_lcd driver & interface program.
The i2c needs to be enabled:
edit /etc/modules-load.d/raspberrypi.conf
And add:
i2c-bcm2708
i2c-dev
to it.

Add the python modules:
pacman install python2-i2c-tools python-mpd2
Then shutdown and install the lcd:
Wiring:
LCD     PI
-ve     pin 6 (5V you MAY get away with 3V3 Pin 1)
+ve     pin 2
sda     pin 3
sdc     pin 5
(All pins are for a Pi B, don't know if they changed on the B+/2)

Boot up and test:
i2cdetect -y 1

It should show this:
[root@runeaudio latest]# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- 27 -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --  
27 is where the lcd is.
Ignore the UU.

Edit the program to set your lcd size (RA_I2C_LCD.py)
look for
lcd_columns = 20
lcd_rows = 4

and change if needed.
To run the program :
python2 RA_I2C_LCD.py

(I didn't use any buttons so you can add them if you need to.)
and it should display the artist & track.
If you don't see anything or a black display adjust the blue module on the back (with a small screwdriver SLOWLY) till you can read the screen.

You have various options in the I2C library - I hacked it about from another web site (see link below), adding extra bits.
Things like cursor/blink on/off, scroll[line #] (not as nice as your bi-directional scroll), line[line #] (to display on line #, variable scroll speed, backlight(on/off), display at a position on any line (x,y).
Will try and document them one of these days, but still hacking it at the moment.

Only just got my LCD working yesterday using the base library (HERE) which I have been hacking to introduce extra functions I wanted.

If you want to hack the driver about be my guest, I am still learning Python so it is probably not optimised at all.
NB it doesn't like /n, no support for spanning using cr. Still looking into that one.

Correction: when installing, it's not python-i2c-tools, the correct one is i2c-tools only, so "pacman -S i2c-tools".

Also, if you're using Raspberry Pi 2, see here to enable I2C: #1287

Hairybiker

It's python2-i2c-tools if you are using python2 like I was, i2c-tools will install the python3 version, since python3 is the default in Arch Linux.

XploD

Hmm, this package doesn't exist:

[root@runeaudio RA_LCD]# pacman -S python2-i2c-tools
error: target not found: python2-i2c-tools

Also, I installed it with "pacman -S i2c-tools" and it works with python2. I run my program with "python2 test.py" and the LCD works great.

schinken

Hello!

This looks very promising and I orderer the i2c-interface and an 20x4 LCD.
While surfing ebay, I found a http://www.ebay.com/itm/121513512643 color LCD, too with SPI interface for same price as the 20x4+i2c.

Would be cool if we get this one running, showing the CD-cover or weather or whatever.

What do you all think?

XploD

Hello,

For a TFT screen, take a look at this topic: #731

I was thinking about buying a color screen as well but they are mostly to small or to expensive, so for now, I'm using a 20x4.

I'm currently rewriting the whole program for this to have more options, to work with 20x4 and I2C interface and for the code to be more tidy (I'll turn it from procedural to object-oriented). Once I finish, I will publish the code and the video to show it. Also, I put the code to github for easier access and updates.

Some screens so far:

Attachments

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: DSC_1548.JPG (53.57 KiB) Viewed 19331 times

XploD

And more (due to only 3 files per post):

Attachments

: DSC_1546.JPG (59.57 KiB) Viewed 19331 times

: DSC_1545.JPG (70.3 KiB) Viewed 19331 times

Peter

I'm currently rewriting the whole program

Hi @xplod

I am really looking forward to this. I have tried so many times, and just end up breaking Rune and having to reinstall. When you publish the I2C version, could you please make the instructions very simple and easy to follow...
I explain it like this - if you have your drivers license in Linux and Python, I am still learning to walk!

Cheers, and thanks for the inspiration.
i

XploD

Hi,

I'm pretty new at this as well, I just have some kind of background since I'm an engineering student but before RuneAudio, I never tried Arch Linux and also I never wrote anything more than "Hello World" in Python. Also, this year I started working with Raspberry Pi and using GPIO for the first time as well. I'll try to make it as easy as possible. Currently it's complicated because there are lots of dependencies for this to work. I should find a better way to include this directly to my program. For I2C, it's easier because I have a library directly included into program. You only have to install Python and to enable I2C and install required tools, I will write a tutorial once I finish.

Where are you getting stuck, on which step?

Peter

Hi there, I eventually got it working!! I am not sure quite how, but it works. With a combination of a majority of @[deleted]'s advice, a dose of @Hairybikers's process - and some experimentation with Arch commands - it works. Now I need to clone the SD card so I have a working copy, before I try to redo and streamline the installation so I can reinstall when the SD card needs reflashing.

Just as an aside...Should this thread perhaps be in the DIY section? Then others who want to implement this great idea can access it more easily than in the general thread.

And lastly... could the code be included in the Runeaudio gitpull/ .4 release?

XploD

Hello. I'm glad that you got it working

About DIY section, sincerely, I haven't seen this section till now

Maybe you're right. And about including it in the release, I don't know. The code is pretty a mess. The new code, maybe, but dev team will decide.

I wrote a completely new code, which supports 4x20, 2x16 and both I2C and parallel displays and it's much better. But currently I have a lot of problems with network on my Pi2, seems that RuneAudio for Pi2 is a mess so I'm waiting for the dev team to fix this. The code is on github, if you want to take a look: https://github.com/RandyCupic/RuneAudioLCD

hondagx35

Hi XploD,

seems that RuneAudio for Pi2 is a mess so I'm waiting for the dev team to fix this

Please tell me more, what is the problem?

Edit:
You mean this one?

Frank

jeroenrood

Thank you XploD,
I've followed your instructions for the first display, and that went well. (A couple of months ago)
Now I've installed a I2C back-pack and installed your second version. With a 20x4 display this is much nicer!
The only problem was that the i2c-dev was not loading. I had to insert the module in /etc/modules-load.d/raspberrypi.conf .
After that, everything works fine,
so thank you for developing the software.
Jeroen.

matock

Hi XploD,

I recently discovered the RuneAudio. Thank you guys for this fabulous project. Thank you also XploD for this tuto. This LCD is the "bonus touch" for an audio server.

I'm trying to install a LCD HD44780 (no I2C, "ordinary" 4 bits wire) on my Raspberry Pi2 with the last RuneAudio 0.3beta. I was able to:
- (python2 was already installed)
- install gcc & unzip
- install the RPi.GPIO library (v0.5.11)
- install the Adafruit LCD library

But I'm not able to tweak the Adafruit LCD library because the folders
/usr/lib/python2.7/site-packages/Adafruit_CharLCD-1.0.0-py2.7.egg
/usr/lib/python2.7/site-packages/Adafruit_GPIO-0.9.3-py2.7.egg
don't exist. The are 2 files with this names in site-packages folder, but no folders.

And of course, if I don't do that I receive the error below when I execute RA_LCD_Buttons.py

[root@runeaudio RA_LCD_Buttons]# python2 RA_LCD_Buttons.py

Traceback (most recent call last):
  File "RA_LCD_Buttons.py", line 11, in <module>
    import Adafruit_CharLCD as LCD
  File "build/bdist.linux-armv7l/egg/Adafruit_CharLCD/__init__.py", line 1, in <module>
  File "build/bdist.linux-armv7l/egg/Adafruit_CharLCD/Adafruit_CharLCD.py", line 24, in <module>
  File "build/bdist.linux-armv7l/egg/Adafruit_GPIO/I2C.py", line 25, in <module>
ImportError: No module named smbus

What can I do?

Thank you very much for your help.
Matock

matock

Hi XploD and all others,

I spent many hours to try to understand what happened (cf my post just above) and finally I found a solution. I'm a beginner in Linux and Python, so may be my method is not the best, but it works.

My guess is the Adafruit libraries and/or the last RuneAudio distro have changed since you wrote your tuto. I expose here a solution. First of all, I precise again the context: Raspberry Pi2 / RuneAudio 0.3beta / LCD HD44780 (4 bits wire, no I2C).

My numbers here refer to the chapter numbers from your tuto.

1) Python2 was already installed (comes with RuneAudio 0.3?). Nothing to do here.

4) Installing RPi.GPIO
No, don't.
Install Adafruit_Python_GPIO instead:

	wget https://github.com/adafruit/Adafruit_Python_GPIO/archive/master.zip
	unzip master.zip
	cd Adafruit_Python_GPIO
	python2 setup.py install

The reason is that the Adafruit CharLCD library needs it.

5) Installing Adafruit LCD library
Yes but slightly different.
Get and unzip the library, then go to the Adafruit_Python_CharLCD-master folder, as described.

5.1) We have to edit and update the source file of the library, BEFORE building and installing it:

	cd Adafruit_CharLCD
	nano Adafruit_CharLCD.py
		- comment the line 24 (as you described): #import Adafruit_GPIO.I2C as I2C
		- comment the line 25 (this module also uses I2C): #import Adafruit_GPIO.MCP230xx as MCP
		- comment the last class at the end of the file (as you described): '''class Adafruit_CharLCDPlate(Adafruit_RGBCharLCD) ... '''

5.2) Then, install the library:

	python2 setup.py install

Et voilà !

XploD

Hello @[deleted], sorry for my late reply, I haven't visited this forum for a few days. I'm glad that you found a solution for your problem and that you got it working, and also thanks for your tutorial! You're right, the cause for your problems is probably the change of Adafruit library, but also, as far as I remember, this tutorial and code was written for Raspberry Pi model B (not RPi2) so there may be some differences as well.

As I already stated somewhere, now I use RPi2 and I don't use this code anymore, I wrote a new one, much better than this one, and you can find it on my GitHub: https://github.com/RandyCupic/RuneAudioLCD if you want to try. But currently it supports only I2C display, I haven't written a class for "normal" 4-wire displays yet. Also, it still needs some polishing so that's the reason I haven't written a tutorial for it yet. I'm planning to change I2C library because this one is pretty slow (visible when scrolling text), I'm planning to add a 4-wire display support and also I'll try to move to Redis client instead of MPD, because on this current code, Spotify won't work on LCD, only MPD (local files, radio and DLNA). Also Airplay doesn't work (it works but doesn't show on display, the same is for Spotify).

matock

Hi XploD,

Thank you for your link. I will have a look when I have some time, by curiosity. My LCD is a normal "4 wire" and I would like to keep this solution. I tweaked a little bit your script and my LCD works fine now.

Thank you again for this work.
Matock

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