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Forum Index : Microcontroller and PC projects : LCD Backpack hits it’s limit.

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Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 11:26am 10 Jul 2016

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Looks like I've finally run out of pins on my back pack Spa Controller....

One left, & once I do away with the LM336, I'll have 2 which can go Wireless serial coms back to another MM.

Cheers

Phil

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9590

Posted: 03:09pm 10 Jul 2016

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Does the water valve -ve have to come from the MM?
Can you not ground-reference the water-valve, and drive it with a high-side transistor switch using only pin9?

That would free up pin10 for you.

It is more then likely I don't know something about the way in which the water valve works - like it is perhaps a two-way valve, and can port water in two different directions or something......

Smoke makes things work. When the smoke gets out, it stops!

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 08:55pm 10 Jul 2016

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Grogster said Does the water valve -ve have to come from the MM?
Can you not ground-reference the water-valve, and drive it with a high-side transistor switch using only pin9?

That would free up pin10 for you.

It is more then likely I don't know something about the way in which the water valve works - like it is perhaps a two-way valve, and can port water in two different directions or something......

That's it Grog,

It's a 2-way valve. 12v DC operated.
Polarity reversed to change the water direction.
Same applies with the single on/off valves; polarity one way for open the other for closed.

Using 2 SPDT relay modules, wired with their common to the motor, NO contact to +12V; NC contact to -12V
So when both are de-energised -ve is to both sides of the motor. Energise either one to transport the valve.

Transit time is about 10 seconds, then they cut out & I can de-energise the relay once I've checked the limit switches.

As it stand I will just scrape in with Com1 available once I ditch the LM336.

Cheers

Phil.

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9590

Posted: 10:49pm 10 Jul 2016

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Okey dokey, thanks for that - ground-referencing the valve -ve won't help then.

28-pin device looks like it has a ton of pins, but it's amazing how quick you use them up!

Time to consider moving up to the 44.....

Smoke makes things work. When the smoke gets out, it stops!

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 10:59pm 10 Jul 2016

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Grogster said
Time to consider moving up to the 44.....

Time to open the draw....

The one with the "bits" in it...

3 SnadPics, 1 Explore 64+ & 2 CGMICROBOARD2's on order.

Two 5" & a 7" waiting to get some attention.

But the CGMICROBOARD2 looks nice to connect things to.

Cheers.

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