Modding an LCD1602 I2C/IIC Adapter Board to enable external PWM LCD backlight control

A big disadvantage of prototyping with LCD1602 character LCD displays is the amount of I/0-pins you need. Of course you can make use of the 4-bit control mode instead of the 8-bit, but you stil need at least 7 I/O-pins.

It's a better idea to use a cheap IIC/I2C adapter board. This enables you to control an LCD (including the backlight) with only 2 I/O pins (SDA & SCL).

You can find these cheap boards for example at DX.com.

These adapter boards contain a transitor driver to control the LCD backlight. The transistor base is driven by an I/O-pin of the onboard PCF8574. This works great to enable or disable the backlight, but it's "on" or "off". Dimming is not possible because the PCF8574 does not support PWM output.

For prototyping purposes I decided to use an external transitor driver on my Arduino Proto Shield.
Via jumpers I can choose what I want: ON/OFF (standard setting) via I2C or Dimmable via external PWM. This is how I did it.

Great Arduino Proto Shield

Arduino really is a fantastic open-source physical computing platform. It is based on a simple microcontroller board, and a great free development environment (IDE) for writing software for the board. No wonder it gained the hearts of an enormous maker community.

I started playing around with Arduino some months ago and it is really great. One problem I was having though is that you have to stack quite some shields only to have basic functionality (buttons, lcd, comms, ...). No to forget additional power supply, extra breadboard, cabling, ... Can become quite a mess on your desk!

2 months ago I found this Arduino prototyping board. It's called the "Arduino Protoshield" and is made by the Italian company Gtronics.

Personally, I think this is a great solution to explore the world of Arduino, here are some great features:

Liga voor Mensenrechten ontdekt ook het Rock Werchter Festival polsbandje

Na mijn blogitem van 2 jaar terug hebben Mo en de Liga voor Mensenrechten ook aandacht besteed aan het fenomeen van de RFID-polsbandjes. Dit artikel vermeldt dat deze technolgie in 2013 op Rock Werchter geïntroduceerd werd. Maar dit klopt niet helemaal: er werd reeds in 2012 geëxperimenteerd met "onwetende" festivalgangers, en hier breng ik het levende bewijs :-)