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Modular Clixx.IO Docking Stations

Although my initial design for an external dock for Clixx.IO has been very useful I've found I need a little bit more flexibility with a wider range of host devices. To that end I've come up with a new design which is a bit smaller but allows you to combine docks to get anywhere from 3 to 9 slots (depending on the hardware capabilities of your host) and as many I2C slots as you need. Design Overview The first major change is a reduction in the number of available slots per dock, it's gone from 6 to 3. I found that the original design with two columns of 3 slots was a little too large for most…

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Controlling a HD44780 LCD Display

The Clixx.IO system gives you at most 3 GPIO pins on a single tab (a digital TwinTab peripheral). In most cases this is enough but there are times when you need more than 3 pins to control a specific piece of hardware. I've already talked about extending the number of pins available for a single slot by using an I2C controlled IO expander - this post gives another example. In this post I'll look at another common use case - controlling a 16 character by 2 line LCD screen. These displays are widely available and fairly popular, you can see an example of interfacing one to the GPIO pins of a Ras…

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16 Key Keypad TwinTab

This post describes how to use I2C peripherals with the Clixx.IO system. Although it focuses on using the Raspberry Pi as a host most of the concepts apply to other microcontrollers as well. It will describe how to set up I2C functionality on the Raspberry Pi, build a Clixx TwinTab with an 8 port IO expander chip interface on it and then show you how to use that to read a generic 16 key telephone keypad. The circuit diagrams and sample code used in this post can be found in my repository so you can duplicate it for yourself. How I2C Works The I2C protocol (also know as TWI or two wire interfac…

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Some Corrections

My recent posts in the introductory Clixx.IO series contained some minor errors that caused the designs to be incompatible with the official Clixx.IO components. I've updated the posts with correct designs. The posts in the series are: Six Slot TwinTab Dock for Clixx.IO * Homebrew Clixx.IO TwinTab * Using the Clixx.IO Docking Station My apologies for any problems this may have caused you. The changes are minor and easy to implement. I'll attempt to be more rigorous with integration testing in future.…

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Using the Clixx.IO Docking Station

In this post I show how to wire the docking station to a Raspberry Pi. We'll then use the homebrew TwinTab board described in the previous post to test it. Raspberry Pi Pin Numbering It is very important to get the pin connections correct from the Pi to the docking station - wiring the pins incorrectly could permanently damage the device, something we want to avoid. The main interface to the Raspberry Pi is a 26 pin GPIO interface on the edge of the board which consists of 2 rows of 13 pins each. A good source of information can be found here, If you hold your Pi so that the expansion header i…

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