Muliple serial ins and serial outs on the same chips.

[steliosm]

Hello everyone.
I thinking of making a modem-like device with a PicAxe. The idea is to be wireless using the cheap 433MHz & 315MHz modules, so I can hook up 2 PCs on a very slooooooow wireless serial connections.

I will need each chip to handle incoming data from the PC and the serial Rx module and output data to PC and the serial Tx module. Serial out is not an issue, but serial in from the module and the PC looks like impossible. The number of received bytes either from the PC or the module will be unknown to the receiving end.

Anyone has an idea on how this could be possible done?

 

[BrendanP]

Checksums are used to ensure all the data that is sent is recieved in its entirity at the other end. Hippy has some information of checksums on his web page. Google Hippy,picaxe etc.

 

[hippy]

One way is to multiplex in two asynchronous serial streams is to have a front-end for each buffering up data until a third can handle either. If you want completely non-blocking receive ( so nothing's missed ) you are looking at X1's which can do background serial. If you used three X1's you could probably create an I2C network.

If you mean PC->TX plus RX->PC ( rather than RX+PC->TX+PC ) then it's probably easier using a separate PICAXE for each channel ( in and out ). You still might want front-ends for each although two X1's might be okay.

If this is PC-to-PC via wireless, you could forget the PICAXE's entirely and just feed the serial to the RF TX and RX back in. That would simply require some hardware buffering. The PC is far better suited to handling unsolicited asynchronous serial than a PICAXE ever will be.

You could make life ultra-simple and just use two XBee's.

 

[steliosm]

Hippy, I had the same idea. I'l just use a MAX232 chip and hookup on them the Rx and Tx modules. Seems like the simplest way to go.
Since I also want to make it ultra-chip a 10euro pair of Tx Rx will fit the bill just fine