rf remote control

Captain Haddock

Senior Member
Has anyone had an rf kefob type remote working with a picaxe project at all? I was thinking along the lines of one of these
ebay things from china sending simple instructions to RFA001 type reciever.
No particular project in mind (yet) just interested.
 

MFB

Senior Member
For that kind of money you have a wide choice of low power/cost 433MHz transmitters and receiver modules that will work directly with the PICAXE rfin and rfout commands. Just use the documentation supplied by Rev-Ed.
 

geoff07

Senior Member
Has anyone done any tests using rfin/out or the NKM2401 to determine just how much better the use of Manchester encoding is in practice? Phase encoding has some useful features but it isn't obvious that it would be better for short 433MHz links, though it is claimed to be.
 

MFB

Senior Member
I have used a couple of the NKM2401 chips with the low cost/power 433MHz that is sold in the UK by Maplin Electronics, with good results over tens of metres using simple 1/4 wave whip antennas. The range is not as good as using FSK modem chips but then these demodulators have integral narrow-band filters. Also, the data rate for Manchester encoding is about half that for FSK when using the same bandwidth link.
 

Haku

Senior Member
Has anyone had an rf kefob type remote working with a picaxe project at all?
Yes, I've bought a couple of these before, no problems wiring the receiver straight into a Picaxe:


Dead simple to setup & use, pressing a button on the remote causes the corresponding line of the receiver to go high (4 buttons = 4 output lines).
The receiver & remote are coded to each other through solder bridges on the sender & receiver circuitboards.
If you get a set make sure the receiver has momentary output as it makes it easier to work with in regards to the Picaxe programming.
 

Captain Haddock

Senior Member
Cheers for that Haku
I have a 2 channel unit here and the reciever board only has vcc/gnd/rxd so not sure what the output will be with that board, I have a 4 channel version but it's currently in use so I'll see what can be done with this one before pulling the other about.
 

Captain Haddock

Senior Member
Well with the 3 pin version gives out a debug reading of 185 using readadc, I don't have enough info on baud rate to try serin and my 18x won't do rfin so I'll have to try it in an 18m2 when it turns up, will also try the 4 channel version as well.
 

Captain Haddock

Senior Member
Hi Haku
Do you happen to know the pinout for that module? I have one here but the only info with it relies on markings that are not on the board itself, I'm guessing the four pins at the end are the button outputs with the 5v+ at the opposite end with switching voltage next and gnd almost in the middle, don't want to fry it though :)
 

Haku

Senior Member
This should help:



You can test it without a microcontroller by putting LEDs (with appropriate resistors) on the output pins, or a multimeter on an output.
 
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hippy

Senior Member
Has anyone done any tests using rfin/out or the NKM2401 to determine just how much better the use of Manchester encoding is in practice?
Only observational tests. Using 'thrown together circuits' I found NKM2401's worked over much further distances than using RF modules plus SERIN and SEROUT.

With NKM2401 and the receiver next to my PC I could read data from a transmitter when I leave the house and go to the end of the street, so about 50 yards and through multiple brick walls, whereas with SERIN and SEROUT it struggled within the house at about 10 yards.

Not scientific at all but it seemed to me that NKM2401 was better on those grounds.
 
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