This is one of my home built Arduino (Homeduino). It shows you how I put together a device I can use for a number of Arduino projects.
This was my wish list:
• More robust than a breadboard solution. This implied it had to fit into a project box of some sort.
• A small as possible so it was convenient to hold and not just rest on a table. The ideal was a thin project box I could strap/attach to the bottom of a conventional PS3 controller.
• A USB serial in/out interface for programming, powering and sending receiving data.
• A USB host to interface to connect a wired PS3 controller.
• A wireless link so that two way communication could be made between the device and other Homeduinos.
• A removable LCD display for user feedback.
• A power supply option to allow powering without being attached via the serial cable.
• LED power on light.
• Reset switch.
I could have used a Nano for the Arduino part but really wanted to do as much myself and have been very impressed with the various Breaduinos and highly compact home builds.
This Instructable shows how the Homeduino was assembled to accommodate all of the above. It doesn’t explain how to program the Arduino or write code to interface with the various components - there is nothing special about the coding and if you are into Arduino you are probably already qualified to write the code. Neither does it detail the wiring as this is again all straight forward and many, many sources of information are already available for building our own Arduino clone and this is nothing more than that.
This is the finished item and it’s all packed inside a project box 1” x 1” x 5”.
Here is another view with the top off. As you can see the major once a prototype has been built and made to work as designed is getting the whole thing packaged into the very small space available.
Here is the prototype on a breadboard.
And here it is in the test environment checking the wireless communications work properly.
First stage is to design the general layout and check the components and sub-assemblies will fit in the space available. Once that has been sorted the build can start.
This shows the processor sub assembly being built on a small piece of PCB. Due to the limited space the ATMEGA328 is soldered directly to the board. You can see the timing circuit and resistors needed for the Nokia5110 LCD display, TX/RX with the USB serial device (CP2102) and the reset circuit.
Headers are soldered on. These will be used to connect the ATMEGA to the other devices.
And the sub-assembly is retested in the breadboard (this time interfacing with a 555 timer chip). Constant testing is definitely required as bad connection hunting later on becomes increasingly difficult.
Now the USB serial adapter and USB host adapter are fitted onto the project boxes base with double sided sticky foam (about 1.5mm thick). Cut away slots are also made in the project box top so that it can trial fitted throughout the remainder of the assembly process.
In this is image you can see the power supply unit has been attached inside the project box top, again with sticky foam, and it has a 2.1mm jack attached which was hacked by cutting down a standard inline jack and then fitting in a hole cut in the side of the project box top. Now it can be powered from a 9v battery or a mains power supply.
To allow the LCD screen to be detached I built a socket from a standard header and bonded it into the end of the project box top after having cut a suitable slot. All the wires needed to loop back in a very small space so special (360 degree bent wire) pins were made.
Also various mini sockets were needed to join up connections and this shows one of them made from a two pin header.
Here is the assembly so far with the processor fitted in the middle between the USB host and USB serial adapters and wiring between them has been started. There is a new component now added and that is the NRF24 sitting above the USB serial adapter. This can be seen supported on a stack of headers which are used like a mini distribution board for GND, 5V and 3.3V.
A small reset switch has been added. It is a hacked tactile switch cut with a taper so that pressure n it will force it into a taper square hole in project box. It is prevented from coming out by the
Let’s have a closer look at the wiring. You can also see the power LCD coming off the back of the power distribution stack.
There you are. Another little Homeduino I built (into a smaller project box) has a ATMEGA328 processor sub assembly similar to this one plus an NRF24 and USB serial port so it can interface with this one and also feed data into my own specially written serial monitor on the PC.