Re: Parallel Port Interface between PIC and PC


Roger Hamlett wrote:
> "Rajiv Ghanta" <rajivghanta@xxxxxxxxx> wrote in message
> news:1116333106.716068.290700@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > hi there,
> >
> > my current project involves designing a circular sonar-sensor array
to
> > be incorporated onto a mobile robot. the hardware design i had in
mind
> > was simple - the sensors would communicate with a PIC via I2C,
which
> > would then transmit the readings to the laptop on the robot. i
managed
> > to implement the I2C interface between the PIC and the sensors. i
now
> > need to establish communication between the PIC and the laptop on
the
> > robot. the laptop has two ports, a USB port and a parallel port.
i'm
> > pretty sure it's much easier to try to develop a parallel port
> > interface. could somebody guide me through this process? i don't
know
> > if this complicates matters, but the laptop on the robot is running
a
> > real-time operating system called QNX. if there are any other
details
> > i can provide, please let me know.
> >
> > any help would be appreciated. thanks,
> The problem is that if the laptop runs a modern OS (W2K, or WXP),
programs
> are prevented from directly accessing the parallel port. Hence the
code at
> the laptop end, will need either A 'kludge' driver to override the
> protection, or a full driver to handle the port for your I/O.
> The easiest way to talk at the laptop 'end', is definately serial.
This
> also has the advantage that most serial hardware has better protected

> inputs, than the parallel port, and only requires two pins at the
PIC,
> while trying to talk to the parallel port could involve using most of
the
> available chip pins.
> The easiest way to get serial, is to use a USB->serial converter
cable.
> These are cheap, readily available, and while some are of 'dubious'
> quality, most now work well. At the PIC end, add a MAX232 to convert
the
> logic signalling to the required voltage and polarity, and you are
done.
> The alternative that is almost equally easy, is to get one of the DLP

> modules based on the FTDI chips. Do a web search on DLP-USB232M.
These are
> small modules that fit on a 0.6" 24pin DIL socket, and implement a
> complete USB serial port, with the signals bought out as logic
levels,
> designed for direct interfacing to processors like the PIC. Some
versions,
> also include parallel pins that can be operated from the software as
well.
> These are designed as 'demo' modules, for people who don't want to
spend
> the time and money, to implement the suface mount FTDI chip, and the
> connections for USB etc., but are a great way for small projects to
get a
> reliable USB interface, without any development time.
>
> Best Wishes


hi roger,

it is interesting that you brought this up. as i mentioned, the robot
does have a usb port, and in fact i did try to use FTDI's FT8U245AM
chip (packaged in a module similar to the one you described). using
this chip, i was able to easily transmit data via parallel from the PIC
to the FTDI chip. i plugged the device into my windows xp machine, and
downloaded the virtual com port drivers off of the ftdi website, and
everything worked like a charm. however, the laptop on the robot uses
qnx. there are third party drivers listed on the ftdi website for qnx
(http://gleb.qnx.org.ru/index_en.html), but i had serious problems
trying to install these drivers, which led me to give up on that route.

my attempt to interface my sonar array with the robot through the
parallel port is a last ditch effort. i know this might sound
ridiculous, but are there any serial-to-parallel converter chips, by
any chance? or maybe i could use the ethernet port? is there
something else i haven't thought of?

thanks,

rajiv

.

Relevant Pages

  • Re: Parallel Port Interface between PIC and PC
    ... >>> would then transmit the readings to the laptop on the robot. ... the laptop has two ports, a USB port and a parallel port. ... >> available chip pins. ...
    (sci.electronics.design)
  • Re: Parallel Port Interface between PIC and PC
    ... > my current project involves designing a circular sonar-sensor array to ... > would then transmit the readings to the laptop on the robot. ... a USB port and a parallel port. ...
    (sci.electronics.design)
  • Re: Parallel Port Interface between PIC and PC
    ... the hardware design i had in mind was ... > then transmit the readings to the laptop on the robot. ... > to establish communication between the PIC and the laptop on the robot. ... > it's much easier to try to develop a parallel port interface. ...
    (sci.electronics.design)
  • Re: Parallel Port Interface between PIC and PC
    ... >> my current project involves designing a circular sonar-sensor array to be ... >> then transmit the readings to the laptop on the robot. ... >> to establish communication between the PIC and the laptop on the robot. ... >> it's much easier to try to develop a parallel port interface. ...
    (sci.electronics.design)
  • Re: Parallel Port Interface between PIC and PC
    ... the hardware design i had in mind was simple - the sensors would communicate with a PIC via I2C, which would then transmit the readings to the laptop on the robot. ... the laptop has two ports, a USB port and a parallel port. ... i'm pretty sure it's much easier to try to develop a parallel port interface. ...
    (sci.electronics.design)