Planning a DIY Data Acquisition/Engine Controller

[dubbleUJay]

Thanks Bruce, I'll have to read it a few time over, just have to go and fix well pump for someone quickly, no water!!

[dubbleUJay]

Bruce, may I run this cct past you for the 16x analog extender with the 4067 before I build please?

From a designers point of view, would it be better to keep the unused/open pins on the IC to Gnd or 5V and would a 100k be OK?

Sorry for the ignorance on my side, give me some relays, motor uni-selectors exec. and I'll build you an electro-mechanical switch board, but my electronics are very rusty as I'm finding out now!

I must still change the controlling inputs from the AVR to run in sequence as you said before, will do that soon.

Thanks in advance,
dubbleUJay

[BruceM]

WJ
It's fine to leave unused analog inputs open, just don't read those addresses. If you want to read them, then pull up or down, but 100K is stingy, check your board for required input impedance.  10K is certainly safe.

Got my PCB back for my battery bank charge controller.  No fatal flaws, just one chip width error, on the 74HCT4067.  An adapter will bail me out. Finished the first pass design and PCB layout for my big 120V 10A linear regulator.  You should see the heatsink- 12x9, 1" fins.  (300 watts dissipation, peak).  I'm going to be very busy for a while!

[dubbleUJay]

Thank Bruce, answers lead to more questions
I was thinking of making the code universal, ie reading all the pins at 1st and if there's problems with timing and such when the rest of the code gets incorporated for other things, just leave the unused ones out. (IF there is problems)
10k resistors won't influence the reading significantly of analog pins if they are present/"left in" on a working pin to ground would they?

Another thing I found while reading the board specs as you suggested, are that the A-pin 4&5 can be used for I2C bus, I'll leave those alone for now as well, might need them in the future. 

I'm glad you got your board back, its a pain waiting for stuff so that one can continue, ask me! 
Pity about the chip error, could you not get the specific package or was it just a fault that crept in along the way?
I've got a similar heat-sink for just such a application, although its 6x6, but 3" fins! Came out of a 3kVA inverter, so it should be ample!

dubbleUJay
FYI Bruce, I previously spoke to you elsewhere about my brother being in Ireland, well he's back now after calling it a "day" after 6 years!
He's use to livin' in town, but now he has moved into a place close to me.
All of a sudden he has to look after/dispense of his own $h!t, literally and figuratively! We've got no water or any municipal services around here. One has to make do by yourself and obviously "big-brother" has been doin' it for about 8 years, so now he wants power backup, running borehole water, exec. and guess who has to help!
Anyway, all in good time!
Talk soon and don't forget to update your thread on the regulator your building! ;-)

[BruceM]

"10k resistors won't influence the reading significantly of analog pins if they are present/"left in" on a working pin to ground would they?"

You shouldn't leave these in- perhaps you can just put pull down resistors on the unused connectors.  Or use a dip header and resister carrier/dip which can be removed.  Or just a place to solder them in but cut away when assigning the channel.

I just assumed that a 74HCT4067 24 pin package would be 300mil spacing- but it was the old style 600mil.  Not fatal, there are adapters.  It cost me just $112 for the circuit board (2) delivered from expresspcb, a bit rework is nothing compared to hand wiring that much stuff!  I had the board in 4 days.

My big linear/mosfet bypass regulator has limited appeal, not too many folks with 120V battery banks!

Today I will daringly drive out to my remote property shop to get parts, do some soldering and do some work on the AC charger assembly. I've been too ill for that for a long time.  It's been very slow recovery from adverse drug reaction (experimental for MS) which caused accute hepatitis, just about finished me off 5 months ago. 

Folks vary in adapting to different lifestyles, I hope your brother will find settling in there not too difficult.

Best Wishes,
Bruce

[dubbleUJay]

You shouldn't leave these in- perhaps you can just put pull down resistors on the unused connectors.  Or use a dip header and resister carrier/dip which can be removed.

I thought there was more to it than meets the eye, for now I'll put up with the sporadic readings on the "open" channels until I'm more sure which would be used or not.

I just assumed that a 74HCT4067 24 pin package would be 300mil spacing- but it was the old style 600mil.  Not fatal, there are adapters.  It cost me just $112 for the circuit board (2) delivered from expresspcb, a bit rework is nothing compared to hand wiring that much stuff!  I had the board in 4 days.

The same thing almost happened to me, luckily the 4067 comes in both, but I'm building one "Vero" for now, so it doesn't matter.
My biggest problem in ZA is availability and services. Don't get me wrong, I can get anything done, but its going to cost me if its not a regular item or service!
The only guy I know about in ZA that does PCB's of "acceptable" quality is this bloke:
http://www.cboards.co.za/pcb_sameday.html
He can make single & "double sided" (No through-hole plating   ) in small quantities:
100x160mm single at about $29
200x160mm double at about $69
The rest of the blokes want a minimum of 20 and up boards at some serious wallet eating prices!!

My big linear/mosfet bypass regulator has limited appeal, not too many folks with 120V battery banks!

If I knew then when I know now, I would have had a nice set of 220Vdc battery banks! We use to install/replace those big glass jar-type flooded lead-acid batteries at the remote telecoms stations I spoke about previously. They were huge, I forgot the capacity now offhand, but they were standing at least 40" tall! A lot of them got replaced on maintenance schedules and were still OK. Most were wired for 50Vdc.
I dropped a number 13mm ring spanner across the buss-bars once by accident while charging a new set! This was at about 2 in the morning as we had our alarm-clock set to wake up on set times to check charging rates.
Needless to say, I didn't sleep after that and could not find anything left from the spanner but little metal balls all over the floor! That bank ONLY had a 400A fuse, nothing serious!   48Vdc at 400Amps are serious stuff, the buss-bars were copper flat-bar approximately 6x1/2".
I must scratch around for my "analog" pictures one day and scan them. Then there was the time lightning struck the tower we were sleeping in, but that's a story for another day!

Today I will daringly drive out to my remote property shop to get parts, do some soldering and do some work on the AC charger assembly. I've been too ill for that for a long time.  It's been very slow recovery from adverse drug reaction (experimental for MS) which caused acute hepatitis, just about finished me off 5 months ago.  

Hope all goes well Bruce, I don't have to say this, but take it easy with the drive!
I got diagnosed with "chronic pancreatitis" about three years ago, no official medication for it so one tries all remedies and sh!t and some of them gives bad side effects as well! Not nice! I now believe they (State Hospital) misdiagnosed me at the time 'cos apparently I would've kicked the bucket by now, but like hell would I go back there now that I'm feeling better! I spent about 1 year in hospital all together for tests, scans exec., before they gave me a diagnose and now it may be wrong!
Medical treatment are REALLY, REALLY BAD in ZA if you don't have medical aid, that's to bottom line!

Folks vary in adapting to different lifestyles, I hope your brother will find settling in there not too difficult.

I believe its a good thing for people to come back to earth some time!
Around here one sees all the folks which let everyone believe they were so well off, getting hit hard in these world wide economic problems everyone's havin'.
They are crying 'cos they have to give "their" stuff back to the banks. I don't mean essential thing, stuff like flashy cars, Johny the 3rd's Blackberry, exec.  
BS, what a farce!!!

Anyway, I talk to much,
dubbleUJay

[BruceM]

WJ,
Did you really find a 6067 with 300 mil spacing- give me a part number, please!

Your circuit board situation sucks- no plated holes?! The quality and prices I've been getting from expresspcb is amazing.  There are some services in China that perhaps you could use, check the sparkfun.com web site for links.

Bruce

[dubbleUJay]

Did you really find a 6067 with 300 mil spacing- give me a part number, please!

Bruce

You probably meant 4067, the one I'm using for the multiplexer board you suggested I use previously.
I got a HEF4067BP (SOT101-1), the broader one, but there's a HEF4067B by Phillips, which looks like the narrow one on the spec sheet, I might be wrong though.
Then there's also the CD74HC4067 by Texas which seems to come in both packages if I look at the specs.
I just hope we're talking about the same dimensions here

About the board making in ZA, I've got a few feelers out to see if I cannot come up with something else, will let you know.
I got the multiplexer going, now just to adapt the code for it, but I'm reading values from it at least.

Hope everything went OK 2day with your traveling, I'm off to bed now, I've got no idea how I'm going to sleep 2night with all this Arduino multiplexer "code" floating in my head
dubbleUJay

[BruceM]

That's great that you got your multiplexer going, and thanks for the chip tips, I'll take a look.

Alas, I didn't get away with my trip, a real setback.  

PS- no 300mil versions of the multiplexer that I can find from my suppliers.  I just bent the first 12 legs out straight and soldered it in as a sip with a 12 wire lean-to.
Fugly!

[dubbleUJay]

That's great that you got your multiplexer going, and thanks for the chip tips, I'll take a look.

Alas, I didn't get away with my trip, a real setback. 

PS- no 300mil versions of the multiplexer that I can find from my suppliers.  I just bent the first 12 legs out straight and soldered it in as a sip with a 12 wire lean-to.
Fugly!

Or 2x IC Holders, 1x300 & 1x600 on top of each other

Bruce, re. the mains monitor I'm busy with: (AS WELL!)
You recommended to use a small PCB isolating transformer with higher voltage out, would 15V be high enough to make the diode drop not to much of a problem or did you mean much higher like 24or48V?

Thanks,
dubbleUJay

[BruceM]

48 sounds better.  You can skip the transformer if you  bond the genset neutral to the mains neutral.

[Crumpite]

Folks,

A very interesting project you're building here !
I've been looking at instrumentation for my 6/1 listeroid CHP that I'm in the process of building/designing.
At first though your system seemed too complicated for my needs, but on second thought perhaps not.
You know how it is, you start out with a few inputs and then think, "well, you know, this would be nice too...", etc..

For my two cent's worth, I haven't seen any mention of a deadman timer.
My nightmare scenario is having my listeroid start leaking crankcase oil into the upper rings and having the engine overspeed until the flywheels burst.
(It's happened)
The first thing I need is a failsafe engine kill system !
I'm considering a spring loaded decompresser lever that's held in place by an energized solenoid hooked to an overspeed sensor circuit that has a deadman timer in it.
I need to check and see if the Arduino has that capability, and if not design something that can do the trick.

I'll come up with a list of inputs and outputs and see how it compares with your list.
Thanks for all the work on this, I think we'll all benefit by this work !
Daryl

[dubbleUJay]

Hi Daryl, yes, this would be a great thing to have if it all works and we keep it as simple as possible. The biggest thing to accomplish seems to be all the various interfacing probes for the inputs. Temperatures up to 125C were no problem, but reading the volts, amps, high temp(exhaust 350C+) and fuel flow is another story, but we'll get there!

I tell myself that if I had to buy a commercial controller/data recorder, I would still have to buy the probes anyway and for that matter if someone wants to buy commercial sensors, they should be able to use them with this project as long as they have/supply an analog output scale of 0-5Vdc to the inputs!

The nice thing about the Arduino is that your "well, you know, this would be nice too..." statement would be easy to incorporate if we have the program/code, so we can do as we like with it. Your "overspeed sensor circuit" would be the Arduino and a lot more!

About the Deadman Switch/Timer, as mentioned elsewhere in this thread, we would have some emergency shutdown outputs from the Arduino.
We could tell it to monitor high temps, AC frequency, Engine rpm, exhaust temperature exec. and if the go out of predefined levels, it would give a shutdown output.
What one then does with this output is up to each guy I suppose. I'll be closing my rack with the existing SOM solenoid as it also opens the exhaust valve as well, but will probably incorporate a secondary fail-safe of some sort as well in the future.
I also thing a software/hardware Watchdog should be in the code to shutdown should the electronics fail, but one should then be able to bypass it for manual operation.

This thread is getting a bit long and the info/ideas is all over the place, once I know myself what's potting, I'll probably write a small preliminary spec of some sort for us to agree/disagree upon

Please Daryl, do give me feedback on you list of I/O's, that's what this thing is all about, covering most/all aspects we can think about.
I might have some knowledge of electronics, programming, mechanics exec., but I'm limited on all, so I'm going to need a lot of help with this thing still!
I'm sure it will be worth the effort though.
I think that commercial units are not obtainable by most people due to cost.

Wilhelm

[BruceM]

I've found the Pic (Pixaxe) microcontrollers to be incredibly reliable and robust.  I one that's been running continuously as a remote PV/battery powered cell phone controller for a few years.  

After that pleasant experience,  for my Picaxe Listeroid controller project, I decided that one layer of protection was good enough for me.  And in fact I think I'm still the only Lister/Listeroid owner with full auto capability with real time monitoring and auto shut down.

The processor monitors oil (high or low), cylinder head temp, rpm, and vibration (Murphy unit I got on ebay). It monitors air pressure so that the engine can be shut down before the 500 gallon(!) tank gets too low.  It shuts down if there's a problem via the same air cylinder actuators used for remote auto start and stop.  Full manual operation is still supported, with processor off, and I can also start manually, then turn it on.  I've run it for a couple years now, zero processor glitches.

I would expect the same reliability from the AVR chips.  Where a watchdog timer (processor must reset the timer as proof of life else engine full stop) might come into play would be with an electronic (full control) governor; a failure or glitch could result in overspeed failure of deadly proportions.

[dubbleUJay]

..............And in fact I think I'm still the only Lister/Listeroid owner with full auto capability with real time monitoring and auto shut down................

HOPEFULLY not for to long Bruce!  

I've chosen the Arduino AVR for its popularity and all the available info/code/hardware for it on the net.
There's Eagle CAD cct/pcb available for a single-sided PCB, bare-bone PCB so one can build it yourself if push comes to shove! Cellular & wireless Xbee has been done exec.
I just hope/believe I made the right choice so that the project can be easily reproduced!

Bruce, such a lot of thing/ideas has changed since the start of this thread, do you think its a good idea to write a short "abbreviation" and post it here so that we might see where we at and if we agree on things?

I'll wait and see 1st what Daryl suggests on his I/O's though, or do you think its a bit to soon

I'd love to get more guys involved/expertize, specially in electronics and programming, not that there's anything wrong with yours, I just know that you're very busy at the moment and I'm going to need some advice/help with coding the Arduino soon! (it's using Processing language, mainly derived from Java from what I gather)
I think its a bit of a pain to go through the whole thread and try and see what its all about, like Daryl pointed out indirectly.

Wilhelm
PS- Bruce, thanks for explaining what a WD was all about, I just presumed everyone knows, what was I thinking!   I would think an external hardware version monitoring a pulsed Output pin to keep it separate from the main board, but that's just because I've done something similar before, as for a software solution, I wouldn't no at this stage