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Old 10-18-2012, 04:59 PM   #81
crane
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Its easy to look at a system like Kladue's and become overwhelmed by the amount of work it would take to get there. Since you are learning electronics and programming as you build your system this makes it even more of a daunting task.

I personally do not have the patience to build a complete automate ebrewery in one big effort. I decided to break down my efforts into stages that provide me with some sort of benefit at each step.

1. I first built an eKeggle and cobbled together some firmware for a PSOC dev kit to drive it. Initially I just had PWM control, but I now have added a temp sensor and can switch between manually and automatic modes. The benefit from this step was to be able to do a full volume boil and do 10 gallon batches. Previously I was doing partial mash in a 5 gallon pot on a turkey fryer burner.

2. The second step was to jump to all grain. I dual purposed a picnic cooler I already had by building a CPVC manifold and buying a cooler bulkhead and valve. In the long scheme of things the CPVC manifold will hopefully be the only throwaway work as I plan to use another keg for a mash tun in the future. When I am not brewing I can take out the manifold and bulkhead and place the original drain back in it to go camping.

3. My next step is to convert the second keg into a mash tun and assemble a RIMs tube. This will allow me to have finer temp control and to do step mashes.

I am in the process of switching jobs so I have been really busy with that and I haven't had much time to work on the brewery but I am finding some time here and there to switch over to the Arduino. As I will be leaving my company next week I need to return the PSOC dev kit and I am not a huge fan of it so I decided to switch to a different micro/platform.

Eventually I want to add a second pump, automated valve control, HLT and who knows what else, but by staging it in such a way that I get some sort of benefit from each step this makes it easier to take on such a large project.

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Old 10-18-2012, 05:00 PM   #82
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Hi

The "cost is no object" approach would be to use multiple external PID's and select which one is active with the PIC. Sort of the 1960's approach. You could set each one to it's control point ahead of time and just let the PIC run a schedule.

No, I'm not going to send you my credit card to fund *that* approach.

Here's a somewhat similar idea:

It's sort of an intermediate between one CPU doing everythig and where you are now..

Do an independant (cheap) PIC processor for each PID. One simple, reasonably bulletproof chunk of code. Set it up for selectable controll points. Select the set point from the master CPU. If you have a selection of 16 points, that's four address wires to route to the PID PIC.

Keep the code simple, just do a setpoint control. For the setup you are building, that's going to work fine. More or less, it's just a couple of IF statements (plus checks to make sure nothing strange is happening).

Since you can flash code the PIC's, you can have a different table in each PID.

Bob

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Old 10-19-2012, 06:23 AM   #83
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I haven't been through every post in the thread, but my experience with (ancient) wire wrapped stuff is that its reliability is decent enough. Back in the day, I hear there were even machines that would wire wrap a whole board, CNC style. Debugging is kind of a pain though.

As for PICs, I know there are opensource PID implementations for them. Here's one done on a pretty low-end PIC (I don't recommend that particular chip though because it's a PITA to work with -- the PIC18F ones are better):

http://www.google.com/url?q=http://w...gSXNnm3sgAJ5pg

My RIMS systems (the old one, and the one I'm building now) are based on the PIC18F46K20, which give you more than enough of everything to control something like a mash temperature. They can also easily handle things like simple (text based) LCD panels, buttons, lights, serial ports, analog inputs (for temp sensors), etc. This stuff is all pretty straightforward -- BUT.. I use these chips at work constantly in industrial controls applications, so I don't have to deal with the whole learning curve! I'm sure it would be a little different (read: slower and more painful) having never seen one.

One nice thing about the PIC is they come in through-hole packages, so you can build your circuit on a breadboard first to see how it works. Once it's functional, I would skip the whole wire wrap thing and just order a board from somewhere like Sunstone Circuits (no affiliation, but I have bought thousands of boards from them). It costs about $60 to have a decent sized board made, and the results are beautiful. As for designing the boards, I'm a huge fan of FreePCB.

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Old 10-19-2012, 05:26 PM   #84
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Thanks for the insight guys. Yes it is mind boggling to say the least, but I do love a challenge. The learning curve has been pretty steep, but the results that I am after are within reach. I kind of like the multiple PID idea, I have a bunch I got from Feebay for pretty cheap, so setting them up like you suggested would be fairly easy to do. I think I have 5 two stage and 2 single stage (hot/cold) plus a ton of 25 and 40A SSR's. When I was buying in the blind I ordered everything in lots or multiple quantities hust in case I let the magic smoke get out and not have to wait for a replacement to arrive. The no holds barred approach to the checkbook is tough on a pension from disability, but I do manage to gather stuff in sufficient quantites over time. In addition to building the tower, the electronics package and brew stuff, I have been building my inventory of common and not so common electronics components too. My electronics bench is about as complete as I would like with O'scope, sig gen, board holders, high quality soldering station and inventory of parts. I can build just about anything from discrete components if I have a schematic. That was the original goal, to be able to just build and not wait on common parts to arrive. Hope you guys are having a great and productive day and accomplishing all that you set out to do.
Wheelchair Bob

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Old 10-20-2012, 02:02 PM   #85
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Hi

If you stick with the DIP package parts PIC's (starting from the 18F series) have a lot of similarity in their pinouts. There are a couple of power pins that show up on the later parts that aren't on the early ones. If you go with the 28 pin DIP package, it exists in a *lot* of PIC families.

Since most / all of the software tools are free, moving from a PIC 16 to a PIC 18 to a dsPIC33 isn't terribly expensive. The programmers work for all of the parts (if you have a new one).

Why bother with all this?

The newer parts are big enough / fast enough / fancy enough to run big chunks of C (or C++) code. The also will do things like 32 bit math. If you get into complex stuff, they may come in handy. If you lay out your board for a compatible footprint, it's just the $4.50 for the chip to put the new one in the socket. That's a pretty cheap upgrade.

Bob

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