{"id":1099,"date":"2013-12-31T16:02:57","date_gmt":"2013-12-31T16:02:57","guid":{"rendered":"http:\/\/www.interactiveclassroom.net\/?p=1099"},"modified":"2014-01-01T00:58:54","modified_gmt":"2014-01-01T00:58:54","slug":"raspberry-pi-project-lcd-screen","status":"publish","type":"post","link":"https:\/\/www.interactiveclassroom.net\/?p=1099","title":{"rendered":"Raspberry Pi Project: LCD Screen Programmed in Python"},"content":{"rendered":"

\"LCD<\/a>For Christmas I received a number of “toys” to play with from my husband. One of which was a geeky box of goodies for my Raspberry Pi that includes a breadboard, wires and an array of other electronic components including LEDs, resistors and an LCD screen. I immediately decided that the LCD screen was to be my \u00a0first Raspberry Pi Project (as I really can’t take any<\/em> credit for the PiSofa<\/a>)<\/p>\n

My first job was to \u00a0solder some connection pins onto the LCD screen so I could connect it to the breadboard and \u00a0Pi using jumper wires. I followed this guide<\/a> online to get me started but modified some of the wiring slightly. In the guide they used the LCD in 4-bit mode but I changed my wiring to set it up in 8-bit mode instead. I also later discovered that I needed some control over the contrast pin so wired in a potentiometer to allow me to adjust the contrast. This is how my wiring looks:<\/p>\n

\"Wiring<\/a>

Wiring diagram for LCD screen and Raspberry Pi<\/p><\/div>\n

To initialise and set up the screen I used another guide<\/a> to gain an understanding of some of the initialisation commands and created a bash script<\/a> to set it all up and check it was working; this revealed a few wiring problems, and was also the point at which I added the potentiometer as the contrast was making it difficult to read my test letter “A”.<\/p>\n

Now it was time for my main mission which was creating a Python program to control the LCD screen. First I worked on creating a program that simply mimicked the bash script, as this was quite untidy I set to work on reducing the amount of repeated code using functions to set pins using binary. In the original guide I had seen the data was set in hex but I prefer using binary as I understand the logic behind it more than using the hex data. Especially as I essentially just want to send True or False commands to the pins.<\/p>\n

By this time I had found an even better guide<\/a>\u00a0 that told me what commands could be sent to the screen for initialisation and what they all meant. To initialise my LCD screen I am doing the following:<\/p>\n