Re: Parallel Port Interface between PIC and PC


"Rajiv Ghanta" <rajivghanta@xxxxxxxxx> wrote in message
news:1116374152.921670.239490@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> 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
At the moment, it is difficult to answer, without knowing what you really
'need' to do. One thought, that would be simple, would be to add a PCMCIA
serial card to the laptop. QNX, should have serial drivers, without having
to get involved in loading any extras, and then the same answer applies,
of adding a MAX232 to the PIC, and using the serial I/O pins on this chip.
I have heard of people getting the FTDI chips to run under QNX. I suspect
the difficulty, is in getting the Neutrino services loaded right. It might
be worth running a Google translation on the Russian manual, and seeing if
anything leaps out.

Best Wishes


.

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. ...
    (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)
  • 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. ...
    (sci.electronics.design)
  • Re: Programmer / Evaluation Board / Development Board
    ... I'll want is a piece of hardware I can use for programming the chip. ... that can hook up to my laptop via USB port / COM port / LPT port. ...
    (comp.arch.embedded)
  • Re: Structured Programming using Forth
    ... so radically different as that just to program a chip. ... Or if you can execute out of each processor's RAM, ... port a micro-next loop repeats the same instruction word without ... In the case of a port another processor has to write ...
    (comp.lang.forth)