magnet control through PIC

[SterlingY]

I understand the 1 of 16 decoder, but I'm lost, those decoders have 4 inputs. Two '154 ICs would require 8 pins from the PIC I'm guessing the 4bit counter resolves this, but I'm not clear how.

Can you be a bit more specific to my untrained brain?

Thanks,

Sterling

[SterlingY]

What about using a 1-wire network to address each magnet seperately? Maybe that's much more costly. I have no experience with 1 wire networks.

[mackrackit]

Depending on the wattage of the magnets, there are several ways to control them. Use PWM or maybe even FREQOUT. Connect the mag circuit to you chip with an opto-isolator or drive the mags with a MOSFET or IGBT. There are pros and cons to each though.

How many more mags than pins? How many mags need to be on at a time? Look at some of the recent post about LEDs, add driver hardware and...

[BobK]

Hi SterlingY,

Don't know your level of expertise, but if it would help, there's a book out for Basic Stamps (these are PIC's) called "The Microcontroller Application Cookbook" that has a chapter on expanding I/O using only a few port pins and it has some code examples. Volume 2 also has some interesting I/O examples. These books are available from www.parallax.com and www.nutsvolts.com and probably from Amazon.com.

HTH,

BobK

[SterlingY]

Thanks for the book info. I'll check them out. Can't hurt to have them around.

As for how many mags to control at once, all of them. I would assume that I have 2 PORTS available for their control.

-Sterling

[Russ Kincaid]

That reminds me of the cemetery joke: How many people are dead in that cemetery? Answer: all of them!

My idea of using the '154 was that 8 of them could be connected with their inputs in parallel. The enable port on the '154 would be connected to 8 pins on the PIC to select the group of 16 magnets. that leaves 4 pins on the PIC for other control.

Russ

[SterlingY]

Forgive me for asking this stupid question, but wouldn't that mean that each '154 would be the same as the others: if output 3 is HIGH on one then it is HIGH on the others?

Another question, which is a better interface I2C or Serial Data? Microchip make a 16 channel port extender in both formats.

-Sterling