From: ldean_at_metrowerks.com
Date: 2001-11-28 22:16:23
Andreas,
As I understand it, with the MCP2150 you can't have the same setup on
both sides because the MCP2150 can only function as a secondary IrDA
device. So you have to have something PC-side to function as a
primary IrDA device or nothing happens. I found a couple of IrDA to
serial converters, but haven't been able to find prices (or deduce
whether they are primary devices):
http://www.decros.com/security_division/security_solutions/parts/irdac
onv.htm
http://www.greenwichinst.com/pdahpc.html
An interesting note on the second site is that Win 2000 does not
support virtual ports. I thought IrDA data could be read as if it
were from a COM port, but apparently not on Win 2000.
It looks like the HSDL 7000 does not transmit IrDA but a much simpler
protocol - it "interfaces with IrDA-compliant transceiver". IrDA
would be fun to do because it is becoming a standard in infrared
transmission, but it may be overkill in this situation.
Laura
--- In buildcheapeeg_at_yahoogroups.com, sleeper75se_at_yahoo.se wrote:
> Hi Moritz,
>
> my computer doesn't have an IrDA port. What do I do? :-) But the
> Microchip device looks perfect for the job if you want wireless
> communication. It certainly feels a lot safer than a opto-coupler.
> But I think IrDA is for the advanced systems and optical fiber for
> the simple ones!
>
> I've done a lot of thinking about this (I'm home on sick-leave
today)
> so please let me tell you what I came up with:
>
> The MCP2150 costs $5.70 in quantities of 100 or more, at Arrow
> electronics you pay $6 for single items. I just found another
device
> that might work though, HSDL 7000. It is not as capable as the
> Microchip IC, but it is much cheaper, you can get it for about
$2.90.
> It is specified for use in medical applications and can be
connected
> directly to an UART, though it needs a baud-rate clock (baud-rate x
> 16) to work. To that, you must add the cost of the tranceiver
> LED/photo-diode. HSDL 1001 might be a good choice for $4 at Arrow
> electronics.
>
> Datasheets can be found here
> http://literature.agilent.com/litweb/pdf/5965-5363E.pdf
> and here http://literature.agilent.com/litweb/pdf/5964-9278E.pdf
>
> So the IrDA solution is $6.90 with Agilent and $9.70 with Microchip
> IC's, not counting the cost for adding IrDA support if your PC does
> not have it (another $7-$10 if you use the same setup on the PC-
side).
>
> One note: A HSDL1001 eats 100mA of current, so it may not be the
> optimal solution for a battery operated device.
>
> Now, does communication with the EEG-device really need to be
> bidirectional?
>
> You mentioned calibration as the main reason.
> I'm assuming here that we want to estimate the frequency response
by
> feeding a signal of known amplitude but with selectable frequency
> into the system, measuring what's coming out at the other end?
>
> What do you think about using a switch that sets the acquisition
unit
> in calibration mode?
> The software would simply ask the user to turn it on at regular
> intervals (perhaps once a week or every 10 sessions). When the
switch
> is turned on, the microcontroller would start the calibration
signal
> and repetedly let it sweep over 0.1 to 100Hz or so, until the PC
> says it is done measuring. That way, it would be possible to drop
one
> data path.
>
> Looking back at the fiber-solution, the Toslink transmitter is just
a
> LED with a driver circuit. For the speeds we are looking at
> (115200bps or less) you can replace it with a simple flat-top LED
and
> the cost for the transmitter drops to 20 cents. Put together with
the
> transistors and resistors (about $.20 each, total of $1.5) the
photo
> diode ($.50) DSUB connector ($1.50) and nylon fiber ($2.50/meter)
you
> get $3.70 or more, depending on the length of the cable.
>
> I know you guys have been working on this for a long time, so I'm
> definitely not the one to tell you what to do or not. I must admit
> the difference is not as large as I thought it would be, and in a
> $100 project, $3 may not matter much. On the other hand, it is
> interesting to discuss different solutions. :-)
>
>
> Be well,
>
> Andreas
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