Questions about Erlang port drivers

Rich Neswold <>
Tue Jan 31 22:25:40 CET 2006


On 1/31/06, Claes Wikstrom <> wrote:
> I don't know about your timer issues, those are probably hard.

The driver now appears to work. I think I've found the solution to my
timer problems. I wanted some verification from someone in-the-know
that would say either "yes, you need to cancel timers before setting
new ones -- we'll update the documentation" or "drivers have
concurrency issues and you're only masking a deeper problem.".

> However if I were to interface such slow hw as RS232 from Erlang
> I wouldn't use a driver. I'd use a regular port program which
> then communicates with erlang either over loopback or stdin/out.

I also have a "Firecracker" X-10 controller and, hopefully, one day
I'll have a "ZigBee" controller (all are home automation devices.) The
ZigBee controller, in particular, would require a faster interface. I
want to specify the X-10 driver in the config file and have each
driver support the same subset of commands.

This gets a little messier when one library is a loadable driver and
the next is an external process, etc.

Plus (barring any concurrency issues I don't know about), the Erlang
driver API is very nice to work with. Most of my time has been spent
trying to find a reliable way to sync with the hardware (which I would
have had to do in the external process). The second item that took
quite a bit of time was the timer issues that started this message
thread. That one "seems" solved.

--
Rich

AIM : rnezzy
ICQ : 174908475



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