Wireless modules and simple setup, what is required?

[Charlie]

OK I've found Dave Houstons excellent examples page, now i guess I just need pointing at a suitable pair of modules.

Can you post a link to the page you are talking about?

[mackrackit]

Mr. Houston's site
http://davehouston.net/

[mtripoli]

I just finished a project using Linx Technologies 900 MHz transceivers. Mouser has them: http://www.mouser.com/ProductDetail/...rSQqdnUWL1o%3d

Super simple to use - these are "air wires" meaning they don't force a fixed protocol on you; you can transmit/receive just about any kind of data you want (literally, serial, PWM, etc). This is a "big deal" if you don't want to get bogged down in the details of using a fixed protocol for your data.

As usual; the data sheet will be your best friend. They have demo systems available (I highly recommend buying the system to jumpstart your project - you can hook your uC to the board and be underway in minutes).

Good luck!

[Dick Ivers]

Hi mtripoli, What range distance are you aiming for with the Linx 900 mhz transceivers? Is your project one-way or two-way communication?

[mtripoli]

This application only required a range around 25 feet. We did an ad hoc test of the system and got more than a 300 foot range using a ~0.75" ceramic antenna internal to the "remote" unit and a stub ~3" antenna on the base unit connected to the PC. With larger antenna's I think the range would easily be 500 feet or more. These are transceivers and we are doing two way comms. Data transmission rates come into play when determining the max distance. As I said, this device is an "air wire"; you can send any kind of "pulsed data". You could send PWM to remotely control dimming, motor speed (don't know that I'd actually recommend that one though). The module itself is very powerful; you can use it under uC control or in a "dumb" mode. Check them out...

[flotulopex]

Hi Tasmod,

I'm finishing a similar project to yours with LINX RF modules.

I choose the 433MHz version to ensure better distance; I tested with a "Splatch" (from LINX too) antenna and reached easely 70 meters. I paid $13.- for the receiver (RXM-433-LR) and $8.- for the transmitter (TXM-433-LR) module.

These RF modules are super-simple to use and it took me less than an hour from unpacking them to have sent the first data

I made this short (simplified testing) code fot the Transmitter:

' Fuses  PIC12F675 - 4MHz XTal
@ __CONFIG _CPD_OFF &_BODEN_OFF &_MCLRE_OFF &_PWRTE_OFF &_WDT_OFF &_XT_OSC

' Registers   76543210
OPTION_REG = %10000000 'GPIO Pull-Ups disabled
INTCON     = %00000000 'Set Interrupts
ANSEL      = %00000000 'Select analog inputs
WPU        = %00000000 'Weak pull-ups (check OPTION_REG)
GPIO       = %00000001 'Set PORTS
TRISIO     = %00000010 'Set I/Os
CMCON      = %00000111 'Comparator Module settings

' Program
MAIN:
    SEROUT2 GPIO.0, 813,["TEST",1] '1200bps
    PAUSE 00
    GOTO MAIN
END

...and the Receiver's code:

' Fuses  PIC12F675 - 4MHz XTal
@ __CONFIG _CPD_OFF &_BODEN_OFF &_MCLRE_OFF &_PWRTE_OFF &_WDT_OFF &_XT_OSC

' Registers   76543210
OPTION_REG = %10000000 'GPIO Pull-Ups disabled
INTCON     = %00000000 'Set Interrupts
ANSEL      = %00000000 'Select analog inputs
WPU        = %00000000 'Weak pull-ups (check OPTION_REG)
GPIO       = %00000100 'Set PORTS
TRISIO     = %00000000 'Set I/Os
CMCON      = %00000111 'Comparator Module settings

' Variables
Led   VAR BYTE
Led   = 0

' Program
MAIN:
    SERIN2 GPIO.2, 813,[WAIT("TEST"), DEC1 Led] '1200bps
    GPIO.1 = Led
    PAUSE 500
    GOTO MAIN
END

[tasmod]

Hi Roger and all,

Sorry I've not replied but I'm on a limited internet connection.

Thanks for that info Roger. Unfortunately the site is full of 433MHz stuff already and they are suffering from clashes occasionally, hence 868Mhz requirement.

I believe the Ciseco modules are serial input but transparent modules as well, I'm not sure regarding this, anyone know better ?

They do have a longer range with suitable smaller sized aerials than 433.

His requirement is up to 3km range in semi open environment, point to point. They will be used in parkland with odd tree here and there. I will be able to carry out range tests once finalised and suspect that one yagi and one whip will suffice. If not, two yagis is not out of the question.

They will be in use for just one day occasionally during the year, probably no more than 3 times. They will be temporary and fully portable.

Rob