Electronic Circuits and Projects Forum

Originally Posted by Nigel Goodwin

As long as you invert the data (easy in software - or use external hardware inversion for the UART), keep the baud rate low, and aren't too concerned about data errors, then you can do a rough serial connection using RS232 type serial.

There's a project on one of my websites (ten years ago) doing just that:

http://www.lpilsley.co.uk/cybot/rx_picboard.htm

But as it's only software, why not do it properly with Manchester coding? - my tutorials went that way following my experiences from back then.

Nigel, from what I have seen from some of these new devices (like the NRF24L01) they are a lot more sophisticated than the old analogue ac-coupled tansmitter/receiver with FSK etc. They allow high datarates and preserve the mark:space of the original signal very well, many of the examples just connect the transceivers to USART or whatever prototcol and it appears that you don't need to use manchester or keep the 1 to 0 ratio even etc as with most old hardware.

Mr Rb from what I have found the tx and rx set Mrdeb posted can use Uart at 2400baud It would be nice if they posted a data sheet of there rx tx set but they don't. Just point you to some arduino code that points you to sparkfun and a set that they did sell.

Originally Posted by Mr RB

Nigel, from what I have seen from some of these new devices (like the NRF24L01) they are a lot more sophisticated than the old analogue ac-coupled tansmitter/receiver with FSK etc. They allow high datarates and preserve the mark:space of the original signal very well, many of the examples just connect the transceivers to USART or whatever prototcol and it appears that you don't need to use manchester or keep the 1 to 0 ratio even etc as with most old hardware.

You're not comparing like with like, that's a 2.4GHz complete transceiver which includes a processor on board and does all the Manchester coding itself. I'm talking about cheap (and dumb) licence free UHF modules - which you can also buy (but more expensively) with Manchester built-in, or as an extra interface chip.

So that module doesn't 'preserve' the mark space ratio, it encodes the data to prevent the need.

The original 555 circuit won't suffer from the perceived manchester encoding issue...

Originally Posted by dougy83

The original 555 circuit won't suffer from the perceived manchester encoding issue...

No, but is completely crap

Originally Posted by Nigel Goodwin

You're not comparing like with like, that's a 2.4GHz complete transceiver which includes a processor on board and does all the Manchester coding itself. I'm talking about cheap (and dumb) licence free UHF modules - which you can also buy (but more expensively) with Manchester built-in, or as an extra interface chip.

So that module doesn't 'preserve' the mark space ratio, it encodes the data to prevent the need.

Sorry Nigel, my mistake. I saw his original link to the RF module and that same ITEAD company sells NRF24L01 modules for $5.50;
http://iteadstudio.com/store/index.p...h78evp84nn5tq5
so I assumed he was using that modern module (or was going to when micros became the plan) when in fact he was using the old 315MHz 1980's style modules...

Originally Posted by Mr RB

Sorry Nigel, my mistake. I saw his original link to the RF module and that same ITEAD company sells NRF24L01 modules for $5.50;

VERY reasonable price

It would be a good choice as long as the shorter range of 2.4GHz isn't a problem.

At that price I quite fancy ordeing a couple, even though I don't need any

Originally Posted by MrDEB

I am only needing to transmit the state of two switches up to 8feet or less (the transmitter is on a helmet while the LEDs, PIC etc are mounted on the back of the bike.
5 feet would do it as well.
I even considered IR but in daylight IR is iffy.

Nothing 'iffy' about IR in daylight - presumably you weren't doing it properly

More of a problem is the degree of 'line of sight' required.

Again, my tutorials show how to do IR 'pic to pic' as well as wireless.

Incidently, following on from my last post - I've ordered a couple of the nRF2401 modules to have a play with, not as cheap as those listed above, but not too expensive (£12.85 inc. postage for the pair from a UK Ebay shop).