Newbie radio link issue

[skimask]

You don't think SEROUT2 running 20MHz could send enough data to change the default setting in the radio module? Is my syntax correct in how I'd send it? If you think that the serout won't do 19200 then I think I'll just cut my losses and try find another module that just works, the manufacturer did say that I could send it back and they would change it in the factory and send it back to me - however they r on the opposite side of the planet!

If you've got a few extra crystals handy (and assume that you just happen to have the right values ), how about tell the compiler you're using 2400 baud with 4mhz, but actually use a 32mhz. The compiler won't know the difference and you'll be running at 19,200.
But since you're running a 16F series, you're probably limited to 20mhz (depending), so maybe, tell the compiler you're running 4mhz with 9600 baud, and actually use 8mhz, to which you'll get 19,200 baud...
But there I go thinking again...gotta stop that...

[mister_e]

yes, tricking the way you said should work... but i don't see any advantage here.

[skimask]

yes, tricking the way you said should work... but i don't see any advantage here.

According to the manual, when using SERIN/SEROUT, 4mhz only get you 2400 baud reliably. Tricking the compiler, a person should be able to get 4800 on 8mhz, 9600 on 16mhz, etc. without too much worry...that's all.
I'm using this sort of thing to work my comm's at 38,400 with a bit more accuracy (I think). My program, running at 40mhz, didn't seem to want to run when compiled with DEFINE OSC 40 and SEROUT2...6 to get 38,400 comm's. But, if I defined 4mhz and SEROUT2...254, and just pretended to be using 3,840bps, it worked like a champ. I dunno, maybe the timing was just off that one or two extra microseconds or something...

[George]

How do I know if I transmit the data inverted or true? What's most likely? Cheers

[mister_e]

Probe your serial PIN at the end of the transmission. If this pin is HIGH, you're in the TRUE mode, unless you're in INVERTED mode.

[George]

Have ordered a couple of linx TXM-418-LR modules - hopefully they will work better for my application - anyone had success with these? They actually look like really good bit's of kit, cheap, small and overpowered! The only downside to prototyping with them is they r SMD.

[Dave]

George, I recently purchased a 2 pair of LINX RXM-433-LR-S and TXM-433-LR-S modules from parallax. They come with antennas and have interface circuitry for level shifting to 5 volt levels. I have used them with manchester coding and a sync pulse and have gotten distances of a few hundred feet. However the baud rate is quite slow as they tend to delay the received signal above about 2 milliseconds per bit. I am currently running them at about 500 baud manchester. Much above and they are unreliable. Don't beleive the claims of 10k baud..... However if you are set on purchasing them I would get them from Parallax, as I said they are fully assembled and ready to be pluged into your circuit. Best of luck....

Dave Purola,

George, Here is the link....
http://www.parallax.com/detail.asp?product_id=28180