12f675_fuse_about_to_blow!

[mackrackit]

Is there any benefit of 315MHZ over 433MHZ?

For the average user both frequencies will work about the same. Generally the higher the frequency the easier it is to to transmit through the typical Faraday cage (re-bar in walls) but 315 and 433 are pretty close.

I would expect around 1/2 mile line of site with these using a 1/4 wave whip antenna, good ground plane, and decent code. Of course the range is farther but it is harder to get reliable data the farther you stretch it.

Here is a code example that for the simplicity is very reliable.
http://www.picbasic.co.uk/forum/showthread.php?t=12554
I would think this code will work with the modules you are looking at.

[LEDave]

Hi mackrackit,

Thanks for that. Half a mile line of sight is a good distance. I think I'll order up the 433 transmitter and receiver modules.

I had a look at Bruce's programs (he's one clever guy) there's lots there to learn about.

Hey maybe I could start by transmitting how many Badger pictures have been taking during the night (if any) and send the data to my LCD. That would save having to take the camera away from the cable release mechanism every morning only to find no pictures have been taken and then re_assemble it the next night (all very fiddly).

Some more interesting stuff to learn about, RF, I like it

Dave

[LEDave]

update:

I've just ordered up the 433MHZ transmitter and receiver modules.

Dave

[LEDave]

Questions:

1/ If you had two circuits, or more to the point two 433MHZ receivers in close proximity, would one transmitter interfere with or trigger both receivers?

2/ If the answer to Q1 is yes, is there anyway (either by software or physically) to slightly change a transmitter and receivers operating frequency to make them totally independent units?

Dave

[mackrackit]

Q1 is yes.

Some modules can be set a little off frequency but most "hobby" types can not. I do not know if the RFPICS can be.

There are also encoder/decoder chips.

But I will say "normally" it is done in software.
Basically think of a computer network. Each device has an address.
If the packet does not have your address attached then the packet is ignored.

[LEDave]

But I will say "normally" it is done in software.
Basically think of a computer network. Each device has an address.
If the packet does not have your address attached then the packet is ignored.

Cheers mackrackit, so it should be possible to send data only to a designated receiver module?

There is a reason I'm asking this.....Another project

The modules have been shipped today (very efficient I must say).

Dave

[mackrackit]

so it should be possible to send data only to a designated receiver module?

Yes and no...
When data is sent it is sent everywhere. It is up to the receiver to "decode" the signal. Even data that the receiver does not understand hits the receiver.

Think back to serial comms with wires. You have a "wait" for something before the receiver acts on the data. Pretty much the same with RF. But with RF there is noise from everywhere hitting the receiver.

Dig through the app notes from these folks
http://www.linxtechnologies.com/Supp...ication-Notes/
AN-00160
AN-00232
AN-00500
AN-00501
Are some good one to start with.

[ScaleRobotics]

It does not like the way configs were defined:

@ DEVICE PIC12F675,MCLR_OFF,INTRC_OSC_NOCLKOUT,WDT_OFF,BOD_OFF
@ DEVICE PWRT_ON,PROTECT_OFF

And some of the names of the registers needed some "E" 's added to them.

Try this instead:

@ __CONFIG _MCLRE_OFF & _INTRC_OSC_NOCLKOUT & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _CP_OFF

Walter

[mackrackit]

And..
Bruce is using PM for an assembler in that example.

[LEDave]

Thanks for that Walter.

Hi mackrackit,

Tonight's silly question: What's PM? Is that a Microchip assembler?

Dave

[mackrackit]

PM is the assembler from the Pic Basic folks. It works well on the older and smaller chips.

MPASM from MicroChip works for everything.

[LEDave]

MPASM from MicroChip works for everything.

So a program written in PBPro would compile and run using the MPLAB IDE?

Or am I North of the North pole.....again?

Dave