Parallella Community

No, of course it's TTL and not RS232, that takes an adapter these days to convert to RS232's +- 25V.

So is the serial header known to work and at what speed?

Dan

Adapters are almost certainly wired as DTEs like the Parallella board is, so Tx on the adapter goes to Rx on the Parallella and vice versa.

Tim

Yay, it works! Thank you for that clue, which nobody else bothered to mention!!!! This info REALLY needs to be on the quick-start. Having a working serial connection greatly reduces the frustration when the ethernet doesn't acquire an address for a variety of reasons. With the adapters and Parallellas being DTE, it means that the 3pin header is effectively mislabelled unless someone can squeeze "DTE" onto it somehow. And looking on the Arduino site about the USB2Serial Light adapter I'm using, darn if I can find anything saying it's DTE.

Dan

Congratulations on getting the link working and on making a null modem cable, which once was almost a data comms rite of passage!

The RS-232 standard has had wide influence in naming conventions over the years, but it is concerned with connecting a computer (DTE) to a modem (DCE). Manufacturers also vary in how which signals they implement which has led to many sales of breakout / patch boxes over the years.

My rule of thumb is if it says modem on the box it is DCE, otherwise it is DTE and to connect two DTEs together needs a null modem cable which pretends to be two modems talking to each other and swaps the signals over. People tend to forget they know this though...

Tim

Edit: I've added a summary of this thread to the since there are many adapters on the market.

Is it possible to connect Raspberry Pi directly and to use it as a serial console?
I have a RPi but don't have a USB serial adapter.
If possible, then how? I'm a n00b at electronics...

Hi,

If the RPi has the same voltage levels as the Parallella, i.e. not RS232 levels, then you should be able to connect Tx to Rx and Rx to Tx.

The the RPi will replace your PC as your Serial Console.


The biggest issue is voltage levels! The Parallella uses LVTTL which is 3.3V. if The RPi has the same level on the port then all's good.


Kind Regards,



Julian.