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PIC Microcontroller Kit

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Norm3000

Jan 1, 1970
0
I am looking for a recommendation on a PIC mircrocontroller kit. I want
to make a timer to control several devices connect to an aquarium
(pumps, lights etc, all standard 120V devices). So I need a kit with
like 8 relays and a PIC chip that I can program to schedule the devices
on daily and weekly cycles. I'd prefer something that has a free or low
cost C compiler available.

I think I can figure out the programming aspect of it but I'd like to
avoid having to design the circuits well as program the chip.

Any ideas or references would be appreciated.

Thanks,
Norm
 
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Tom LeMense

Jan 1, 1970
0
Hi Norm,

Does it HAVE to be a PIC? As much as I like working with PIC's (and I do),
there are other microcontrollers out there that are probably better
supported by free or low-cost C compilers:

Freescale's HC08 family is supported by code-size limited CodeWarrior
http://www.metrowerks.com/MW/Develop/Embedded/HC08/Default.htm

Atmel AVR is a GCC target, and (because it's not always straightforward to
get GCC up and running under Windows) here's a Windows-based port
http://sourceforge.net/projects/winavr/

If you've got your sights set on the PIC, I've used the SourceBoost C
compiler with good results
http://www.picant.com/c2c/c.html

A Google search on "relay board microcontroller" came up with loads of good
hits - choose your relays carefully, though.

have fun!

TJL
 
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petrus bitbyter

Jan 1, 1970
0
Norm3000 said:
I am looking for a recommendation on a PIC mircrocontroller kit. I want
to make a timer to control several devices connect to an aquarium
(pumps, lights etc, all standard 120V devices). So I need a kit with
like 8 relays and a PIC chip that I can program to schedule the devices
on daily and weekly cycles. I'd prefer something that has a free or low
cost C compiler available.

I think I can figure out the programming aspect of it but I'd like to
avoid having to design the circuits well as program the chip.

Any ideas or references would be appreciated.

Thanks,
Norm


Parallax www.parallax.com sells starter kits using Basic.
A free C lite compiler can be found:
http://www.computer-solutions.co.uk/chipdev/hitechc.htm#Hitech
A good intro:
http://www.voti.nl/swp/n_index.html
To name just a few. A little Gooogling will reveal much more.

petrus bitbyter
 
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John Fields

Jan 1, 1970
0
---
How do you plan to _not_ design the circuits and still get what you
want?^)
 
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Byron A Jeff

Jan 1, 1970
0
On Sun, 10 Jul 2005 17:07:44 +0200, "petrus bitbyter"


How do you plan to _not_ design the circuits and still get what you
want?^)

I believe he wants prepackaged hardware that only requires software.

Personally if that's the case, then maybe getting a prepackaged controller
is the way to go.

Maybe somethin like this?:

http://store.yahoo.com/webtronics/unrelcark6.html

BAJ
 
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Norm3000

Jan 1, 1970
0
I believe he wants prepackaged hardware that only requires software

That was the idea. I can handle C programming and I'm sure I can figure
out how to toggle the PIC I/O ports off and on at set intervals.
Problem I have is how to then get the I/O port to drive a relay to
switch my 120V devices. From what I've seen/read over the past could
days it doesn't look like it's as simple as connecting the relay to the
I/O port of the PIC chip. Advice I've gotten so far includes adding a
transistor and resitor to drive the relay or using an H-Bridge. I'm
clueless here, if anyone could provide an example schematic of driving
a relay off of the I/O port that would help tons

I'm not dead set on PIC. It just looked to me that the chip specs were
good (16 I/O ports on the chip I was looking at) and there appears to
be a lot of support/information for PIC processors and compilers on the
web.
 
J

John Popelish

Jan 1, 1970
0
Norm3000 said:
That was the idea. I can handle C programming and I'm sure I can figure
out how to toggle the PIC I/O ports off and on at set intervals.
Problem I have is how to then get the I/O port to drive a relay to
switch my 120V devices. From what I've seen/read over the past could
days it doesn't look like it's as simple as connecting the relay to the
I/O port of the PIC chip. Advice I've gotten so far includes adding a
transistor and resitor to drive the relay or using an H-Bridge. I'm
clueless here, if anyone could provide an example schematic of driving
a relay off of the I/O port that would help tons

Not the cheapest solution, but for low noise, minimum parts count,
solid state relays (with input tied between positive PIC supply and
active low output) is hard to beat. No other parts needed.

That said, there are some very low power relays than might be driven
directly by a PIC output, but their contact ratings are terrible.

Probably the next simplest is an N channel mosfet, gate connected
directly to the PIC active high output, source to PIC negative supply
rail, with the relay coil tied between something like a 12 volt
positive supply and the drain. You also need a diode across the coil
(cathode to positive supply) to suppress the inductive spike at turn
off. Of course, this only works if the negative side of the relay
supply is connected to the PIC negative supply. You will also need a
bypass capacitor connected between the positive supply connection of
the relay coil and the source of the N channel mosfet to contain
switching noise. One good way to achieve this is to use a 12 volt
unregulated supply for the relay, and use a linear regulator to
produce 5 volts from that to supply the PIC.
I'm not dead set on PIC. It just looked to me that the chip specs were
good (16 I/O ports on the chip I was looking at) and there appears to
be a lot of support/information for PIC processors and compilers on the
web.

I like them.
 
J

Jonathan Kirwan

Jan 1, 1970
0
That was the idea. I can handle C programming and I'm sure I can figure
out how to toggle the PIC I/O ports off and on at set intervals.
Problem I have is how to then get the I/O port to drive a relay to
switch my 120V devices. From what I've seen/read over the past could
days it doesn't look like it's as simple as connecting the relay to the
I/O port of the PIC chip. Advice I've gotten so far includes adding a
transistor and resitor to drive the relay or using an H-Bridge. I'm
clueless here, if anyone could provide an example schematic of driving
a relay off of the I/O port that would help tons

I'm not dead set on PIC. It just looked to me that the chip specs were
good (16 I/O ports on the chip I was looking at) and there appears to
be a lot of support/information for PIC processors and compilers on the
web.

PIC is a good choice. MPLAB is relatively easy to use, the assembler
and linker are quite decent, and it can directly talk to various
programming tools. I've got both a PICSTART+ (with the modification
that allows MPLAB to update its code, automatically, for newer
processors) and an ICE2000, so perhaps I'm a little spoiled though.
But the chips are pretty hardy and I have to say that the technical
support staff, while a few of them may be 'dry', are pretty well
versed folks on the details. And, although I haven't called them in a
few years, it was only the price of the long distance call to get
ahold of them. So worth it, I think.

A lot of folks like the Atmel AVR. I certainly am one of them, though
my attitude has gone through "mood" swings regarding the company,
Atmel. My support is through a local FAE and this is mostly a bad
thing for me, by comparison with Microchip. Funneling questions via a
local FAE who has to support a large number of various products, none
of them perfectly, and having to wait a day or two for responses --
isn't all that great.

The TI MSP430 is enjoyable for me. But for starting out, I wouldn't
recommend it.

All of which gets me back to probably adding my recommendation for
PICs. I think they would be a good choice, given what you've said.

However, I think most of the C compilers for it cost something, but
there may be some code-size-limited versions around for free. You
should research this part of the question, though. Also, if you are
looking for preconfigured boards to play around with, I really am of
little good. I just haven't used any of them.

Jon
 
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petrus bitbyter

Jan 1, 1970
0
Norm3000 said:
That was the idea. I can handle C programming and I'm sure I can figure
out how to toggle the PIC I/O ports off and on at set intervals.
Problem I have is how to then get the I/O port to drive a relay to
switch my 120V devices. From what I've seen/read over the past could
days it doesn't look like it's as simple as connecting the relay to the
I/O port of the PIC chip. Advice I've gotten so far includes adding a
transistor and resitor to drive the relay or using an H-Bridge. I'm
clueless here, if anyone could provide an example schematic of driving
a relay off of the I/O port that would help tons

I'm not dead set on PIC. It just looked to me that the chip specs were
good (16 I/O ports on the chip I was looking at) and there appears to
be a lot of support/information for PIC processors and compilers on the
web.

Have a look at:
http://www.velleman.be/Downloads/0/Manual_K5201.pdf
Although the outputs come from an EPROM, you can connect a PIC output the
same way. If you browse through the Velleman catalogus you will find other
examples as well, even with a PIC:
http://www.velleman.be/Downloads/0/illustrated/Illustrated_assembly_manual_K8015.pdf

petrus bitbyter
 
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