confusion with rf modules and serial link

Forum 2005-2010 (read only) Hardware Interfacing
1

I want to try and get a data link with handshaking going, but as a first start I have 2 Arduino boards, one on my pc and one on my laptop.

I thought that as a beginning I would hook them up Tx to Rx, Rx to Tx plus ground, and just get each returning a message and flashing the LED every second.

But I need the serial ports to program the chips dont I ?

And if I did get it programmed, would I not have problems regaining control via the serial USB using these ports?

I have done some searching but there seems to be no definite guidance ( see http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1147888882 for example )

I will then want to try and connect two radio modules that I bought before the holidays, that are supposed to be like a transparent link,

http://www.rfdesign.co.za/Files/5645456/RFOEM%20manual1.5%20Montar%20LH%20pdf.pdf

which is why I want to connect them to pins 0 and 1, the modules have all the preamble, CRC etc built in, so I assume that would confuse virtualwire ?
And I am powering both modules via the usb port for these tests, so the serial link to the pc would still be connected??

Has anyone done something similar and can give advice...?

2

With two Arduinos with a single hardware serial port each, you'll need to use software serial ports to get the two boards to talk to each other. Look at using NewSoftSerial. Connect the software TX pin on one to the software RX on the other.

Then, use the hardware serial class (Serial) to talk to the PC on each end, and the NewSoftSerial instance to talk to the other Arduino, on each Arduino.

3

Thanks, I will have a look at newsoftserial again, and post my results.

4

I don't see an explanation of newsoftserial, but I ran newsoftserialtest.pde on both of them, and I can type an input to either machine and get some hyragliphics on the other, so in the morning I will try and write something that wont have them doing the same thing !

5

Not bad, looks like a nice transceiver, lot of features. Need to supply Vcc of 3.3V (almost like an arduino was in mind ...)

Are they expensive?

Oh & Yes - if you have something else connected to Rx while the PC tries to send in on Rx, it will bomb out with the failed sync 0x51 message you see posted so often.

6

I have gone back to the hardware serial, and just pull the wire from each pin 0 when I download the chips.

I have a hardware little checking loop running, next I must try it through the rf link , but I have added a code to switch off the tx between loops as its on the same frequency as the communal electronic traffic gate outside my house :slight_smile:

These OEM modules are more expensive (US$27) than their nRF905 OEM Carrier Module,($15) or the bare chip of course, once I get used to them I will use the breakout board or the bare chip if I want to go smd.