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I'm looking to assemble a very small circuit to transmit data from a gyroscope and/or accelerometer to a computer via wi-fi. It also needs to be self-contained (so should contain a power source).

The circuit should be as small as possible because it needs be mounted to a hula-hoop for used in a performance. As I have zero experience in electronics, it seems like the Arduino boards would be a good start, but they all appear to be too large for my needs.

I can program, so interpreting the data shouldn't be an issue.

Could anybody point me in the right direction?

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  • \$\begingroup\$ WiFi and very small is not an easy combination because WiFi is relatively power-hungry. I don't know any ready-made modules that do this, but you could combine an RF transceiver like an RFM73 with an accelerometer, a microcontroller and a battery. Something in the 5 .. 20 gram region whould be possible if the battery doesn't have to last too long. \$\endgroup\$ – Wouter van Ooijen Sep 24 '12 at 12:49
  • \$\begingroup\$ Bluetooth might be better if the range is suitable. You might be able to locate an accelerometer with serial output and a bluetooth-serial interface, which would simplify the project. \$\endgroup\$ – pjc50 Sep 24 '12 at 13:12
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There is no need for WiFi or Bluetooth or even a microcontroller. All that adds to your size and power consumption.

The output of a 6 axis sensor is a serial bit stream. E.g. The Invensense MPU6000 is about 4 x 4mm and takes about 1mA.

You will need to drive and configure the device, so a small FPGA, e.g. An Actel Igloo FPGA is also about 5x5mm and takes less than 1mA could be used. It might be possible with some 6 axis sensors to use pin strapping or device defaults so driving and configuration ( and hence the FPGA) might not be required.

The output of the FPGA is passed to the input of the RF transmitter. Depending on the required sample rate (hence data rate) You could use a descrete chip like this MRF24J40 or a module like This for the RF transmitter.

If you keep the data rates down you could probably run for many hours on a very small battery assuming the transmit distance is not too far.

You would then use a microprocessor board, e.g. The Arduino or Rasberry PI with a matching RF receiver device to pass your data to a computer or tablet over USB, Ethernet or WiFi.

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  • \$\begingroup\$ Simplicity-wise: Why an FPGA in particular (as opposed to a uC)? \$\endgroup\$ – boardbite Sep 24 '12 at 16:19
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Basing your design on existing Arduino designs might be a good idea if you're (rather) new to electronics as you can easily prototype your entire design with know working hardware and then just combine the main board + shields + extras into your own design and create a product from that.

Given Arduino's open license (which most shields also use) you're free to use it as you want.

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I recommend you mbientlab sensors... they have very nice bluetooth acelerometers having very good results ... You can read data and chart, export to excel from easy app, metabase mobile app ... is really easy to install and use and very effective ... it´s true that sometimes you have to reset devices and teh frequency is lower than 400Hz, so for high frequency meassures can be an issue,

https://www.metawear.com/ https://mbientlab.com/tutorials/Apps.html

Marc Parpal @ Hewlett Packard

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