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Hi,

I have just completed a writeup of my robot line detector circuit and
BasicX software. It is available from my projects page:
http://home.austin.rr.com/perks/basicx/Projects/

Mike





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Mike after glancing over your schematic, you could easily eliminate the
LM339 and related passive components with a single PIC or probably AVR
chip. I'm a PIC guy...

- Tom

--- In basicx@basi..., Mike Perks <basicx@a...> wrote:
> Hi,
>
> I have just completed a writeup of my robot line detector circuit and
> BasicX software. It is available from my projects page:
> http://home.austin.rr.com/perks/basicx/Projects/
>
> Mike




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tombhandley wrote:

> Mike after glancing over your schematic, you could easily eliminate the
> LM339 and related passive components with a single PIC or probably AVR
> chip. I'm a PIC guy...

Tom,

Is there something I'm missing here? The whole point is to offload line
detection from BasicX (or other master controller). Inserting another
microcontroller might may sense but my guess is you won't be able to
replace the 3 trimpots. Are you really suggesting a $2-4 microcontroller
instead of a 42 cent LM339 and a few resistors.

What kind of circuit are you suggesting? For example does it mean using
an AVR with builtin ADCs and 3 comparators?

Mike





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Mike, if cost is the issue, stick with what you have. If parts count
is an issue, you can eliminate all the pots and resistors with a
single PIC. Many PIC chips have multichannel comparators and A/Ds.
Thresholds are programmable. On the down side; you would need PIC
tools and experience... Atmel chips must have similar capabilities
but, until I got into the BX-24, I have no experience there... I'm
just a hardware guy that 'hates glue' be it passive or active...

- Tom

--- In basicx@basi..., Mike Perks <basicx@a...> wrote:
> tombhandley wrote:
>
> > Mike after glancing over your schematic, you could easily
eliminate the
> > LM339 and related passive components with a single PIC or
probably AVR
> > chip. I'm a PIC guy...
>
> Tom,
>
> Is there something I'm missing here? The whole point is to offload
line
> detection from BasicX (or other master controller). Inserting
another
> microcontroller might may sense but my guess is you won't be able
to
> replace the 3 trimpots. Are you really suggesting a $2-4
microcontroller
> instead of a 42 cent LM339 and a few resistors.
>
> What kind of circuit are you suggesting? For example does it mean
using
> an AVR with builtin ADCs and 3 comparators?
>
> Mike




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Mike to follow up...

The cost 'trade-off' is PCB area and manufacturing costs assuming
this may be a commercial product. When you factor in board assembly
costs alone with all the passive components, QC, and Calibration in
your case, that ~$2 processor starts to look attractive depending on
quantity.

- Tom

--- In basicx@basi..., "tombhandley" <gr13tbs@c...> wrote:
> Mike, if cost is the issue, stick with what you have. If parts
count
> is an issue, you can eliminate all the pots and resistors with a
> single PIC. Many PIC chips have multichannel comparators and A/Ds.
> Thresholds are programmable. On the down side; you would need PIC
> tools and experience... Atmel chips must have similar capabilities
> but, until I got into the BX-24, I have no experience there... I'm
> just a hardware guy that 'hates glue' be it passive or active...
>
> - Tom
>
> --- In basicx@basi..., Mike Perks <basicx@a...> wrote:
> > tombhandley wrote:
> >
> > > Mike after glancing over your schematic, you could easily
> eliminate the
> > > LM339 and related passive components with a single PIC or
> probably AVR
> > > chip. I'm a PIC guy...
> >
> > Tom,
> >
> > Is there something I'm missing here? The whole point is to
offload
> line
> > detection from BasicX (or other master controller). Inserting
> another
> > microcontroller might may sense but my guess is you won't be able
> to
> > replace the 3 trimpots. Are you really suggesting a $2-4
> microcontroller
> > instead of a 42 cent LM339 and a few resistors.
> >
> > What kind of circuit are you suggesting? For example does it mean
> using
> > an AVR with builtin ADCs and 3 comparators?
> >
> > Mike




(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

tombhandley wrote:

> Mike to follow up...
>
> The cost 'trade-off' is PCB area and manufacturing costs assuming
> this may be a commercial product. When you factor in board assembly
> costs alone with all the passive components, QC, and Calibration in
> your case, that ~$2 processor starts to look attractive depending on
> quantity.
>
> - Tom
>
> --- In basicx@basi..., "tombhandley" <gr13tbs@c...> wrote:
> > Mike, if cost is the issue, stick with what you have. If parts
> count
> > is an issue, you can eliminate all the pots and resistors with a
> > single PIC. Many PIC chips have multichannel comparators and A/Ds.
> > Thresholds are programmable. On the down side; you would need PIC
> > tools and experience... Atmel chips must have similar capabilities
> > but, until I got into the BX-24, I have no experience there... I'm
> > just a hardware guy that 'hates glue' be it passive or active...
> >
> > - Tom

Luckily I don't need to worry about commercial quality hardware design.
If I did I wouldn't be using stripboard and I would be using a better
design. But I got the point and a similar point also applies to software.

BTW Unless you can replace the trimpots by some easy software comparator
setup, they are always needed to tune the detectors to the particular
environment (or line detection course if you are competing). Nothing
beats the usability of a simple screwdriver.

Mike





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> ... Nothing beats the usability of a simple screwdriver...

I absolutely agree. It is very satisfying to feel a tactile adjustment
instead of senselessly entering a numeric one. Still, I once used a
mouse encoder that had a perfectly made-to-suit hexagonal tool
receptacle in the center. It mounted just like a miniature pot.

You wouldn't know that it wasn't a multiturn analog adjustment. Tom
Tom Becker
--... ...--
GTBecker@GTBe... www.RighTime.com
The RighTime Clock Company, Inc., Cape Coral, Florida USA
+1239 540 5700



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--- In basicx@basi..., Mike Perks <basicx@a...> wrote:
[snip]

Mike, I still keep a 'calibrated' trim pot tool (a pot tool that makes
it easy to turn pot screws) just in case. The calibration depends on
how much sleep I've had ;-)

- Tom

> BTW Unless you can replace the trimpots by some easy software
comparator
> setup, they are always needed to tune the detectors to the particular
> environment (or line detection course if you are competing). Nothing
> beats the usability of a simple screwdriver.
>
> Mike





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