Note: You can now request a welding service (small) for this article :-)
Positive LCD Display + keypad interface for Raspberry-Pi
Here is a nice product Adafruit that makes it very easy to use a LCD display 2 lines (2x16 characters) for any Raspberry-Pi. We really like RGB type displays because they offer an excellent cachet to projects. Unfortunately, these LCDs require a lot of digital pins, 6 to control the LCD display and 3 others for the RGB back-light... so a total of 9 pins. It's almost all the pins available to the GPIO of the Raspberry-Pi!
It's with these characteristics in mind that Adafruit has designed a display to make it easy to include in your projects. That is how they designed this plate for Pi that takes control of a 2x16 character LCD display, up to 3-pin back-light control AND 5-pin input for a 5-key Keypad... while using only the 2 pins of the GPIO reserved for the I2C bus! The best part of all this is that you don't lose these 2 pins since you can connect I2C sensors, a RTC (Real Time Clock) that all share the same I2C bus.
It's a great way to add a display without being bothered by a ton of connections.
This second generation now has the buttons of the Keypad placed on the right to improve the mechanical stability.
This Pi-Shield is perfect if you want to realize a standalone project with its own user interface. The 4 directional buttons + the selection button makes it possible to realize a control system without having to connect a computer.
The Pi-Shield is designed for revision 1 and revision 2 of the Raspberry-Pi. It uses I2C bus (SDA/SCL) pins. The Pi-Shield is delivered with an extra-large 26-pin connector... So the Shield takes place above the USB and Ethernet connectors.
LCD positive = RGB back-light
At present, the code and the kit can control the LCD RGB back-light by turning on/off each of the LEDs. This means that you can display the colors: Red, Yellow, Green, Bluish green, Blue, Purple, White or all turned off. On a positive LCD, the letters are dark on a colored back-light.
There is no PWM support to control the back-light. If you need a more granular control of the RGB back-light to display a wider range of color, you should know that this shield doesn't know how to do it (the 'I2C expander' circuit doesn't have a PWM output).
This product is delivered as a kit to assemble! Including a high quality card (PCB) and all components (buttons, connectors, etc). Positive LCD display 2 lines of 16 characters is included!
Mounting this shield is easy, even if you have never done welding before. The kit can be mounted in 30 minutes.