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Wireless Transmitter Shield

Posted: Mon Aug 12, 2013 7:43 pm
by charlest
Hi, I would like to link up 2 Arduino boards, one as TX, the other as RX.
It seems you provides a RX shield, how about a TX shield?

Re: Wireless Transmitter Shield

Posted: Wed Aug 14, 2013 12:59 am
by angusgr
For the transmitter side you should be able to use any "ASK encoding" 433Mhz module.

Jaycar sell this one, which I've used before:
http://www.jaycar.com.au/productView.asp?ID=ZW3100

If you get a Protoshield like one of ours you can just mount it on there.

Just bear in mind it's 3.3V so you'll need to drop the 5V TX "high" signal from the Arduino to a 3.3V one. You can do this with a voltage divider (two resistors), or you can use one of our logic level shifter modules: http://www.jaycar.com.au/productView.asp?ID=XC4238

Cheers,

Angus

Re: Wireless Transmitter Shield

Posted: Wed Aug 14, 2013 8:35 pm
by charlest
angusgr wrote: Just bear in mind it's 3.3V so you'll need to drop the 5V TX "high" signal from the Arduino to a 3.3V one. You can do this with a voltage divider (two resistors), or you can use one of our logic level shifter modules: http://www.jaycar.com.au/productView.asp?ID=XC4238
Angus, thanks for your suggestion. In regards to the 3.3V power requirement of the above TX module, I was wondering whether I could use my Eleven R3's 3V pin to power the module directly without the voltage divider or the logic level shifter.

Re: Wireless Transmitter Shield

Posted: Thu Aug 15, 2013 1:27 am
by angusgr
charlest wrote:
angusgr wrote: Angus, thanks for your suggestion. In regards to the 3.3V power requirement of the above TX module, I was wondering whether I could use my Eleven R3's 3V pin to power the module directly without the voltage divider or the logic level shifter.
Hi Charles,

Your entirely right that powering it from 3.3V is best done via the 3V pin on your Eleven.

The other issue however is driving the TX (data) pin on the module. Usually modules are designed for their data lines to be driven at voltages no higher than their power supply, so a 3.3V module will expect the "high" signals on the digital data pins to be not much higher than 3.3V. The Eleven provides 5V when a digital I/O pin is driven high.

There are such things as "5V tolerant" input pins on some device, where the device may be 3.3V but it is advertised as being able to handle 5V input levels without being damaged. These are unfortunately not very common.

However, I just skimmed the data sheet for the ZW-3100 module in question and realised that I gave you bad advice before. Datasheet says "Supply voltage range 2.2 - 5.5V". Given this information you're better off powering it from 5V directly in this case (not 3.3V), and just wiring the digital output directly to the DATA pin. Forget everything I said about level converters!

- Angus

Re: Wireless Transmitter Shield

Posted: Thu Aug 15, 2013 6:55 pm
by charlest
Angus, thanks for your clarification.