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I would like to deploy some wireless, battery powered sensors around my house that will wake up regularly and send readings to an Arduino base station receiver. To keep the cost per sensor low I have been looking at using an ATTiny85 MCU with a simple one way RF link.

For the RF link I was initially looking at units like this which just exposes a single data input wire and would work with the Arduino Virtual Wire library. I ended up buying a TX/RX pair from Maplin.

I have now realized that the units I chose are much more complicated to wire up. The datasheet describes the 14 pins but I am at a loss about how I should be wiring these up. In particular, on the TX module:

  • There are 3 GND pins. Do I need to wire all of these to GND?
  • SDI/SCK/nSel - I am guessing that these pins are to do with configuring the module. How would I wire them up and what code would I need to run on my Arduino to configure the module?
  • FSK - I think this is the single wire to send data on. Can I use the VirtualWire library with this input?
  • nIRQ - This is the interrupt line. Can I ignore this or must I handle interrupts?

EDIT: The datasheet says "The ALPHA Transmitter is a low cost FSK transmitter. It needs only an MCU, crystal, decoupling capacitor and antenna to build a high reliability FSK transmitter"

Where do I need to wire in a capacitor?

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You must connect all Gnd pads.

The Arduino has an SPI function you can use. You need to wire the SPI pads (SDI, SCK) to the Arduino SPI pins. You also need to connect nSEL to an Arduino output.

FSK is the data input.

You can ignore the interrupt output.

You need suitable antennae, a simple 1/4 wave piece of wire should work.

You have a lot of learning and experimentation ahead of you.

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  • \$\begingroup\$ Thanks for the reply. Just to be clear, SDO on the receiver would go to the MISO pin? SDI on the transmitter would go to the MOSI pin? Can I use FSK with the VirtualWire library? What code do I need to use on my Arduino/ATTiny to control the SPI+nSel pins? \$\endgroup\$ – mchr Dec 29 '11 at 13:23

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