Post by thread:Tx/Rx 418MHz, decoding using a PIC

I have a project needing a data link (sending 10 bytes) for remote control. I am using a 418MHz miniature Receiver and Transmitter. The Rx o/p goes high on receipt of a carrier (o/p fed to a PIC) and so I will need to detect a start bit then a security number to ensure it is not noise then 10 data bytes then a CRC byte to verify all was received intact. The Tx will be fed from a PIC to send the start+security byte + 10 data bytes + CRC byte. Before I 're-invent the wheel' has anyone done this before, and if so, is any standard code available? Thanks Stephen H Alsop spam_OUTsteveTakeThisOuTs.ssystems.easynet.co.uk S&S Systems Ltd http://easyweb.easynet.co.uk/~s.ssystems

On Wed 17 Dec, Stephen H Alsop <.....steveKILLspam@spam@S.SSYSTEMS.EASYNET.CO.UK> wrote: > > I have a project needing a data link (sending 10 bytes) > for remote control. I am using a 418MHz miniature > Receiver and Transmitter. The Rx o/p goes high > on receipt of a carrier (o/p fed to a PIC) and so I will need to detect > a start bit then a security number to ensure it is not noise then > 10 data bytes then a CRC byte to verify all was received intact. > > The Tx will be fed from a PIC to send the start+security byte + > 10 data bytes + CRC byte. > > Before I 're-invent the wheel' has anyone done this before, > and if so, is any standard code available? Are you in control of the protocol used on the other device as well? Since this is On-Off-Keying, you could imagine using some kind of simple synchronous protocol. As it happens, this kind of thing is not dissimilar from a RS485 network. I've written some code for home automation purposes, that uses a simple 16kb/s synchronous protocol with PWM. The protocol sends and receives packets of 5..37 bytes which include a 16-bit CRC, and node addresses etc. The code for this home automation project (still in progress) is available on the web: http://www.xs4all.nl/~falstaff/picres.html Frank PS. It might even be feasible to run an IP stack on these, although with the data payload of only 31 bytes max, it may not be very efficient. Enough to run a tiny http deamon on your pic, perhaps...? ------------------------------------------------------------------------ Frank A. Vorstenbosch Phone: +44-181-636 3391 Electronics & Software Engineer or: +44-181-636 3000 Eidos Technologies Ltd., Wimbledon, London Mobile: +44-976-430 569