RF link with Arduino

More photos can be found in the RF link album:

http://picasaweb.google.com/galileosky/RFLink


Here I use two Arduino boards for the RF link experiments.
The RF TX and RX modules are off-the-shelf products which you can buy them from the local radio shops. The modules I use are 315 MHz AM.





The TX module.




The RX module.




Arduino shield for the TX module. (I re-use the shield of Nunchuck.)



For RX module, I use breadboard for quick setup.

New oscilloscope

This is the new oscilloscope I purchased last week.
My older one (GOS-658G) is out of order when I was trying to measure the level shifter voltage of the Wii Nunchuck interface shield. Besides, 658G is an analog OSC, which is not very useful when measuring transient signals or digital data. So finally, I made up my mind to get a digital OSC.
This one is 100MHz DSO, with 1GS/s sampling rate. The memory depth is 25K points. By the way, it has USB mass storage port, which is very convenient when waveform storaging is demanded.
For a Tek DSO, these features may cost me twice or more.

ATmega168 arrived

I bought these ATmega168-20PU from the internet auction site. Not cheap, but this is the most convenient way to get these parts. I couldn't find them in the local radio shop. Even the on-line shope of the Atmel agent doesn't carry this part.

Basically, these parts will be used for my arduino adventure in the near future.

When Arduino Meets Wii Nunchuck

When Arduino Meets Wii Nunchuck



The Nintendo Wii Nunchuck controller.




The Wii Nunchuck extension cable.




The extension cable out of the box.




Cut the extension cable and we got 6 color coded wires plus one shield wire.




Make it a Molex 2.5 mm connector and secure the conjunctions with heat shrink tube.




Find the best locations for the headers on the multi-purpose PCB board.
Since the distance between the two digital headers is not standard 2.54mm pitch,
I have to sacrifice one of them on this shield.




The headers soldered in place



The Molex connector soldered in place.




This is how the shield connected with Arduino.
I let the headers protrude out of the PCB on component side on purpose.
This way I can use the jump wires to connect them to the breadboard for other experiments.
Also I can clip the probe on them to monitor the Arduino ouputs or inputs.




The Nunchuck shield mounted on Arduino.




The soldering side of the Nunchuck shield.




Another view of the soldering side of the Nunchuck shield.




The component side of the Nunchuck shield. Most of the area is not used yet.
The left most area is planned to be the 3.3V and Nunchuck area.
Since the RESET button on Arduino is not easy to access on this configuration, a RESET button installed on the Nunchuck shield.





The Nunchuck shield mounted on Arduino.




This is the first version of the Nunchuck shield I built.
The 3.3V regulator I used is LD1117. Simple and efficient to get 3.3V from 5~12V input voltage for Nunchuck.
I used two resistors as the level shifting devices between Nunchuck and Arduino.
But later on, I found it don't work. The low level can't reach 0.6V or lower.




Power on the Arduino and Nunchuck shield.
The amber LED on the Nunchuck shield is power indicator of 3.3V.




The Nunchuck extension cable connected.





This is the 3rd (final) version of the Nunchuck shield board.
Actually I'd tried to replace the resistors with diode (1N4007) to try to get the logic low level to 0.6V. But it didn't work either. So in the final version, I used two N-channel MOSFET (2N7000) as the level shifters. The logic low level now reaches as low as 0.2~0.3V. It works perfectly now.
In fact, I found the N-channel MOSFET being the good device to drive high current (or power) circuits for MCU designs.



See the two TO-92 devices? They are the level shifters MOSFETs (2N7000).




Arduino + Nunchuck shield board transimitting the Nunchuck readout via the serial port.




Arduino + Nunchuck shield board + Nunchuck on line.




The X-accelerometer readout when I waved the Nunchuck.

The StopWatch board

This is the stopwatch board I built for measuring the video latency of our video processing board.
The main MCU is ATmega16-8PU which is running at 4MHz clock, provided by the 4MHz oscillator. All of the segments of the 7-segment LED display are driven by individual I/O pin. That means it is not driven by the conventional scanning method. In this way, I can achieve higher response time which is critical when doing the video latency measurements.
Also, the display pattern is not conventional 0~9 digits, but special design simple patterns are used instead. This improves the readability when it is switching from current to next pattern.
A Start-Stop-Clear button is shown on the board (the blue one). Three power sources are provided. But the USB power is not usable because the board seems to drain too much current.
The 10-pin JTAG connector is there to help debugging and burning firmware into the internal flash of the MCU.

AVR STK500

This is the development and experiment platform for my AVR projects.
I bought it form the Atmel agent in Taiwan.
It is very convenient for concept tests and realization.
Also I used it as ISP programmer when doing experiments.

MCU related interests

I redefined this blog as my MCU (Mircrocontroller) related interests sharing space.
I'll post all of my experiments and studies here.