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Topic: General TX/RX (Read 2399 times) previous topic - next topic

baum

Many of you are probably familiar with the General TX and RX from sparkfun, little bird, etc. They are cheap, but supposedly are not accurate.

I can use the virtual wire library to send data between two arduinos. But how could I send digital temperature sensor readings to an arduino without and arduino on the transmit side? Is it practible? Are the radios good enough? Or should I just get a breaduino or something with the virtual wire library on it?

Grumpy_Mike

Quote
But how could I send digital temperature sensor readings to an arduino without and arduino on the transmit side?

It depends entirely on your sensor. Is there a way of getting it to output data in response to  something like a pulse train. Or do you have to trick it in a more sophisticated way. You could end up making a state machine out of discreet logic gates but in these days of cheap processors it would not be a cheaper option. If I were doing this then I would look at some of the TI transmitter modules you can get with built in processors. The development kits are quite cheap.

baum

I want to take something such as this http://www.sparkfun.com/products/9418
and just have a wireless link output the raw data, which can be read by arduino. I want to minimize the hardware necessary on the transmit end (if possible).

CrossRoads

Read the datasheet Baum - that part must have some smarts to go with it to configure it and to read the data after the conversion is done.
Maybe you can use something less than a 168/328 based arduino, like one of the attiny's or something.
Look here for other supported processors
http://www.avr-developers.com/
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

OK, then. I'll try something else. Can I just have a pushbutton?

CrossRoads

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

pushbutton wired from 5V to tx module data pin, pulled down to gnd.

CrossRoads

How will wiring the TX data pin to ground do anything? Not  going to transmit much that way.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

No... like this:




Would that work?

CrossRoads

Sure that would work.
Or use the internal pullup  and short to ground to sense a 0 instead, 1 less part to wire in.

I don't understand how this ties in with the temperature chip & reading it & sending out that data over an RF link?  Did we change topics along the way?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

No, topics have not been changed. If I have a button that can "output" a 1 or 0 that would work, wouldn't a temp. sensor that outputs 1s and 0s work, too?

CrossRoads

http://www.open.com.au/mikem/arduino/VirtualWire.pdf

Read up on how virtual wire works. The TX side needs to put out enough data for the RX side to recognize what is going on - think of it like software tuning in of a radio station. Virtual wire sends enough bytes to accomplish that tuning in, along with the data, and with some encoding to make sure the data is not corrupted.
So, you need some smarts to read the temp sensor, put the data in an array for example, and then send the data out so the characters can be reassembled on the other end.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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