1-line digital thermometer DS18B20 to LinuxCNC

Blackwind wrote:

One simple question: someone hookup a DS18B20 style temperature sensor (one line comms), to a pin in LCNC?

I can't find any references to doing so on the Wiki. However it looks like something that could be relatively easily done in software on the parallel port.
To guarantee < 15uS pulses the software would need to have a "reset" function as used by the parallel port driver, but other than that it looks moderately straightforward so write a HAL module to do it.
en.wikipedia.org/wiki/1-Wire

Blackwind wrote:

I have assumed that I had to write hal module to do it, and it seems simple, but thats beyond my current programming skills.

It sounds like fun, so I just ordered a few temperature sensors to play with.

It looks like there would need to be external hardware, unless you happen to have an open-collector parallel port (bidirectional pins).
www.maximintegrated.com/app-notes/index.mvp/id/3230
Shows a scheme for 2-wire devices which can probably be modified.

Yes, you load the parallel port driver as IN or OUT when you start the configuration.

JT

Blackwind wrote:

but 2 to 9, can be in/out pins, this is an pp specification?

It might be possible to use the pins as in/out in the semi-undocumented "X" mode. But I don't think that creates both sets of HAL pins. (and is only safe with certain models of parallel port)
www.linuxcnc.org/docs/html/hal/parallel_port.html

The problem is that one-wire needs to both be able to drive a pin low to signal to the devices, and set the pin high then read the value back to see if they are pulling it low.

One-wire might be possible with a single pin with changes to X-mode in the parport driver, but only for some parallel ports.