in reply to Perl to control hardware

Perl is fine for hardware control as long as you aren't really speed-conscious. For dealing with serial I/O, I've used Device::SerialPort and Event. For dealing with the parallel port, you could use Inline. You don't say what OS platform you're on; if you're using Linux, you could use ioperm to gain access to the address ranges for the parallel port, or use /dev/parport. Under Win9x (DOS) you could use Inline directly to talk to the parallel port. Under NT, I'm not sure.

I wrote a module for dealing with external hardware through the I2C and/or SMBus (in my case, a smart battery and smart battery charger, but you could also get to CPU temperature sensors, serial A/D converters, etc.). Under Linux, there's already the i2c drivers and the lm-sensors project; if you use this, the bulk of the work is already done for you.

I also hacked one of the i2c-algo-bit device drivers to work with the Maxim SMBus interface card; if you're interested in this, /msg me.

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Re: Re: Perl to control hardware
by toma (Vicar) on Jul 25, 2001 at 09:29 UTC
    I have my choice of OS between Linux, WinNT, Win2000, and HP-UX 10.20.

    It should work perfectly the first time! - toma

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      I remember reading about an NT program that one could use to change the IO permissions for another program. Sorry I can't give you a pointer to it right now, but it was available for free from a company that sold training for NT device driver writers

      If you can use Linux, it's easy to get to simple hardware. You'll have to have a more complicated driver if you need DMA or interrupts, though. Still, if it's just a parallel port, Linux is easy. Likewise for the I2C implementation (or, indeed, USB or anything else that there's drivers for).

      If you do, say, a Device::IOPerm, I'm sure people will use it. I'd do one, except that I don't need it right now. But Inline is your friend.

      I did find that there is insufficient support in the i2c bit-banging protocols for doing block reads and writes from the i2c bus. This may or may not be a problem for you; if you're connecting your i2c stuff via a simple buffer to a parallel port, it could be a problem. However, my module should give you Perl access to byte and word read and write. If you need block read/write, you may want to use a "real" i2c interface; either on the motherboard (hint: there's probably one going to your memory devices!) or an add-in board.

      Many single-board computers capable of running Linux and Perl have SMBus connectors on-board.

      Remember if you use a parallel port to disable any OS-level drivers that may be wanting to use it. I just compile my embedded Linux kernels without parallel printer or parport support; you could also use modules for these drivers (and not load them or unload them) or explicitly inhibit the parport driver.

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