Chapter 14 of the Oppendahl book
http://www.club100.org/ftp/m100-oppedahl-2.pdf has a good summary of the
hardware.
Basically the port provides a 1 or 0. With a barcode you'd time the
transitions to form the number. Clearly the hardware is fairly primitive
and a lot needs to be dealt with in the software. Voltage to frequency
converters work well in this situation if you want analogue to digital
conversion.
Regards, Mark.
On 18/06/15 23:34, Kurt McCullum wrote:
It's curious that it can be passively checked or tied to an
interrupt.I read one of the Portable 100 articles about attaching a
photo transistor to it which got me thinking about a few projects. I
think it was being used as a stopwatch for that application. But it's
definitely a port with possibilities.
Kurt
On Thursday, June 18, 2015 3:22 PM, MikeS <[email protected]> wrote:
It's actually a pretty useful port and the +5V availability is a real
plus.
There's a Portable100 article about using it as a tachometer (although
ISTR that the software left something to be desired) and although I
haven't tried it it should be a straightforward interface for a
temperature- or voltage-to-frequency converter (e.g. Maxim 6576 &
6577, Analog AD7740 etc., even just a 555).
If memory serves, I think Steve did something like that for his
aquarium heater or something similar.
And you can even use it to read bar codes!
m
----- Original Message -----
*From:* Kurt McCullum <mailto:[email protected]>
*To:* Model 100 Discussion <mailto:[email protected]>
*Sent:* Thursday, June 18, 2015 5:39 PM
*Subject:* Re: [M100] Barcode Wand
Thanks for the info!
On Thursday, June 18, 2015 2:14 PM, Doug Jackson <[email protected]
<mailto:[email protected]>> wrote:
Yes,
From memory, the wand has *no* smarts - the phototransistor is
basically converted to TTL and provided to the interface pin.
It was very similar to the HEDS3000 series wands that HP used on
the HP41
(http://www.ecse.rpi.edu/Courses/CStudio/data%20sheets/HEDS3050.PDF)
I have both the TRS80 wand and the HP in storage here if anybody
wants information.
Doug
On 19/06/2015 6:56 AM, Kurt McCullum wrote:
Does the barcode interface use a TTL level signal? Meaning any
TTL barcode scanner that is wired properly could be used?
Kurt
--
Kindest Regards,
Doug Jackson
<b>Dougs Word Clocks.com Pty Ltd</b>
ACN: 159 352 753
35 Fred Lane Crescent, Gordon, ACT, 2906, Australia
em:[email protected] <mailto:[email protected]>
ph: 0414 986878
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