Ah. Well, I stumbled across that post while still trying to catch up on my learning curve, which is still lagging behind. Wish I found the forum years before, when I was still burning chips with now outdated software. Still have my Pocket Programmer eprom burner and its original DOS program disk, heh. Back then, the new LT-1 didn't exist. Crap, I'm getting old.
On the bright side, I still haven't woke up with my underwear destroyed.
Wanted to drop in an update since getting things put back together again. I'm still battling valve noise, so I'm probably going to have to yank the even bank cylinder head off again. This has significantly hampered my ability to make progress with the controller firmware. Because I'm scared to run the car too much testing has been very limited and I haven't even been logging data but merely feeling and listening (mainly for valve noise). I do occasionally hear a stumble or misfire, but nothing I can reproduce consistently. Overall it runs well and throttle response is nearly as good as before the tune changes to compensate for cam timing.
I did have a chance to download and start learning how to use Eagle a couple weeks ago. This looks like a project in and of itself (designing a pcb). I'm going to be on vacation next week and hope to spend some of my down time working on converting the schematic to Eagle and possibly starting on a board layout.
Last edited by spfautsch; 05-28-2018 at 02:35 PM.
Preliminary eagle .sch and .brd files uploaded to github (link in sig).
Attached pdf is 2x actual size of pcb layout. Actual board size is 88x59mm (3-7/16" x 2-5/16"). This was my first worldly attempt at designing / routing a pcb so I'm going to spend a lot of time verifying and re-verifying before I pay to have a sample produced. If anyone has experience / wisdom they'd like to share in this area I'm open to any and all suggestions.
For this initial board layout I used simple solder pad connections for the wiring harness (see pics from post 356 for the connectors and wiring I used on the protoboard) and aimed to make the footprint as small as possible. Ideally I would like to have a waterproof case including ~30 pin connector that would solder directly to the board, but I've yet to find anything that's affordable in small quantities (less than 50). As mentioned previously my personal solution will be to find / make a tray type case with mounting tabs and pot the board into it with two-part silicone or something similar.
Nice work! I have been too distracted lately. Been learning stuff about the Speeduino project in order to "update" my friend's 4cyl inboard boat from 1980 with throttle body fuel injection. A Roomba was given to me for father's day. (I suspect an inside joke about role reversal made about me) So, looking at this very determined little machine, I might use my new skills to make a "Lawnba" to annoy my neighbors with fits of jealousy.
Are you going to use a socket for the Pro Mini, or just solder in?
Thanks - this was quite a learning experience in itself.
When you get the Lawnba perfected, the next logical progression is to mount a remote controlled gun turret w/ camera on it. I've got some rabbit problems I'm thinking that would help with. :-)
My prototype is soldered and I was planning to solder the "production" one also just for added piece of mind that it won't vibrate loose. I haven't had any problems flashing from the driver's seat over serial so that shouldn't be an issue.
I've been cleaning up and compacting the board layout more over the last few days to allow for optional components like pull-up resistors and the like for the spare output pins. I've also been straightening up the component names so the silk-screen layers will be legible.
In researching the crystal circuit it occurred to me that it might be worthwhile going to a temperature compensated oscillator package. But that might be something for rev 2 of the PCB.
Unfortunately I'm sort of in limbo with being able to test and further refine the firmware. The good news is it starts and runs great. Unfortunately cold starts are about as far as I go because as soon as it gets up to temp the knock sensors start picking up the valve clatter. Before we left on vacation I made a short idle log w/ eehack from cold to closed loop, and noticed the knock counter rolled over (i.e. 0-65535) several times in the course of 10 minutes.
Adding insult to injury, about that same time we found out my wife needs to have her gall bladder removed so I'm not going to be spending much money on stuff like this until the checks from the insurance companies clear. So it may be August or September before I can budget the time or money to pull the noisy head off and get the guides checked out. :-\
I have already built an early version of the auto turret, back when 1 ghz was fast. I didn't write it, though. These guys did. https://github.com/sentryGun53/Project-Sentry-Gun Got lost in the move, though. heh.
Sorry to hear about the upcoming surgery. Sounds like there will be no more greasy food in her diet. My wife had her gall bladder fired, also. Does not slow her down much, but she has been without for about 10 yrs, and had time to adapt.
The noisy valvetrain problem has me puzzled. Having a tough time visualizing it. Hope the guides are bored straight. I saw one nascar head with valves so huge they threatened to touch each other if they weren't perfect. Not sure if valvespring coil bind is happening, either. That can get pretty noisy, too. At least that can be checked externally. After that, I am out of ideas.
I'm not so much puzzled as (to use clean language) frustrated about the valve noise. I suspect I have a couple exhaust guides that didn't get honed quite enough and the valves are getting close to seizing - or at least requiring more force to open when they get hot. But that's just my theory. They were certainly making less noise when I ran them without oil seals. I'm kicking myself for not using the micrometer on them when I had the head off last. Lesson learned - double-check everyone's work. :-\
I just uploaded the final design of the rev1 schematic and pcb to github (link in sig). I found a manufacturer and ordered 10 (the price was the same for 5 or 10). Luckily because this isn't a very compact design and I could keep the minimum drill size above .030", the price was extremely reasonable. I chose the "slow boat" $8 shipping option so I may run out of patience before they show up, but the faster shipping options cost more than the boards.
Here are some pdfs of what I'm having made. Fingers crossed...
In addition to a couple optional resistors and caps and a solder pad for the status led so it can be wired to an external (i.e. dash mounted) led, I also added grounded screw mounting pads at the corners that increased the board size significantly. This version is 3.625"x2.75".
Last edited by spfautsch; 06-22-2018 at 06:47 PM.
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