wirless link for On/OFF and 3 switches

[MrDEB]

Need two different designs for a wireless link. Thinking about using these
https://www.sparkfun.com/products/8945

https://www.sparkfun.com/products/10533
One app is a On/OFF control of a pic circuit.
second app is three switches and send via wireless link which switch has been closed.
The data sheet for the transmitter / receiver show an ic from Holtek but source?
Laipac tech which sells the transmitter / receiver want $40 min order and $40 shipping.
Found same at Sparkfun for less $$
Contemplating maybe DTMF might be a method but have never worked with DTMF , RX, TX circuits. Been finding circuits but locating a parts source??
Any suggestions??

 

[Sceadwian]

Application is critical to chosing the right part, what range do you need and what degree of reliability?

 

[4pyros]

One app is a On/OFF control of a pic circuit.

This can be done with a simple one way RF remote control, many out thare about $10

second app is three switches and send via wireless link which switch has been closed.

This is a two way app. Try ZeeBee.

 

[MrDEB]

this is a one way app and only need up to 8ft max.

 

[Sceadwian]

The modules you've chosen seem fine for that as long as the objects in the way aren't large.

 

[MrDEB]

for the on/off switch, the button to activate the switch is to be located in the drivers compartment of a vehicle while the receiver/pic circuit is located near the front bumper.
The 3 pos switch is all open air.
How to implement (DTMF) might be less complicated? using the mentioned transmitter and receiver. Unless a simpler method ??
COST is a factor as is supply.
The Holtek parts look easy but ?

 

[4pyros]

I would look at Keyfob transmiters and Receiver Modules
**broken link removed**

 

[MrDEB]

WAY too expensive at $36 per unit.
Needs to be less than $3 per unit

 

[4pyros]

Needs to be less than $3 per unit

Yah good luck with that!
How many are you making, I thought it was a one off.
Keep looking some of the keyfob sets can be had for around $5.

 

[MrDEB]

this is a proto type for a marketable product.
Got to wondering if by using the https://www.sparkfun.com/products/8945 and https://www.sparkfun.com/products/10533 to transmit/receive a set of pulses.
have a 555 astable with the 3 switches changing the frequency output. The PIC then decode what frequency for which switch .
Example R1 = 10K R2 = 1K selectable caps= .1uf,1uf,10uf
Could just have selectable resistor for R1. Pic could? be programed to detect number of pulses. Might be easier that going with a DTMF setup.

 

[4pyros]

this is a proto type for a marketable product.

Maybe we should have cleared that up a long time ago.

What kind of security requirements is there? That will be the main factor on the protocol selection.

DTMF ( dual tone) is old and I find it hard to get parts for.

Yes use single tones!!!

 

[MrDEB]

No security requirements.
I am even considering maybe using a PIC in the transmitter section. Program the pic for three different frequencies that are transmitted. The receiving PIC just translates the frequency to determine which switch is closed momentarily. I might not even need a TX/RX module I posted. Just add a simple tank circuit?
As for the ON/OFF circuit, perhaps use the modules posted since most cars have radios that would pickup the transmitted signal?
DTMF may be a lot more than I need. Just a single set of frequencies (only three are needed). Transmitter range is not critical as only need no more that 8ft.
A PLL would perhaps be considered to avoid stray frequencies but if the PIC is programed for say a 100khz frequency ONLY stray signals would be voided?
Looking into a simple 7555 transmitter circuit for the ON / OFF app.

 

[4pyros]

I might not even need a TX/RX module I posted. Just add a simple tank circuit?

In an auto you need to be able to deal with several sources of noise. Some stuff that can be hard on the car radio, like ignishoin noise. Blue tooth, FM transmiters in the car and all kinds of outside sources. Just do to its unpredictabilit, It may not be reliable. What would happen if the car is passing by a big radio transmiter tower. I dont think a car is the best place for a RF link.

 

[MrDEB]

The ON/OFF is for the car. The 3 switches are for a bicycle
I think I found what I am looking for. https://www.coolcircuit.com/project/rf_remote/

 

[4pyros]

I think I found what I am looking for. https://www.coolcircuit.com/project/rf_remote/

I see no code for that poject.
I have been looking around and fould some info that mite be of use to you.
The standerd encoding/decoding chips for RC cars and the like; holtek HT12E and HT12D, old but still avalible.
Also look at Reynolds Electronics, Thay have preprogamed PIC chips for encoding/decoding up to 8 bits.
There are some RF remote control set kits on the web as well, and many IR sets that can have RF added.
Hope this helps.
Andy

 

[MrDEB]

The source code is down at the bottom of the link page but its in high tech C
the code would not be to difficult to write BUT I m only slightly familiar with SWORDFISH which onlt supports the 18F pics.
The Holtek chips may be the way to go.
Will look at Reynolds as well

 

[4pyros]

The source code is down at the bottom of the link page but its in high tech C

Sorry I missed that, I thought that thay were ads.

 

[MrDEB]

Thanks for the heads up on Reynolds electronics
Looks like they have everything I need.
Will compare shipping etc.

 

[4pyros]

Ya thay seem to have alot of stuff.