Parallella Community

I think Andrew's idea was to connect the RPi's data port to a 4 way or 8 way switch matrix and use the RPi's GPIO buss to switch the switch.

This could be done all with logic chips.

To switch 4 ways would need 2 GPIO lines and 8 way would need 3 GPIO lines.



Using standard GPIO lines as UARTS is possible, but you would need to write the "bit banging" and UART code to be able to do this, something I had to do for my VHDL course I did when doing my MSc.




Kind Regards,



Julian.

A quick way of getting a couple of extra UARTs would be something like an ARM microcontroller board (e.g. the microcontrollers on ST's "discovery" boards have 3 or 4 UARTs).

But most likely the easiest way is to have multiple USB RSR232 converters on a hub connected to the RPi or other master machine. In that case I'd be tempted to go for a Vista licensed ultra SFF PC (e.g. Lenovo M58p) which having a gigabit NIC could also be a storage server for the cluster. And for that matter it'd probably be able to supply enough 5V for 8x Parallella boards, into the bargain.

The down side of using USB / RS232 converters is that they output RS232 levels +/- 12V.

The Parallella's only use LVTTL levels of 0V to 3.3V.

For the USB / RS232 converters to work there would have to be MAX3232, or similar, converter ICs at each Parallella to convert back to LVTTL.


Kind Regards,


Julian.

Thanks everyone!
I'll be careful not to connect to the wrong pins.