Become a fan of Slashdot on Facebook


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: Re:Reminds of of something at a past job (Score 1) 765

by EETech1 (#49314983) Attached to: A Software Project Full of "Male Anatomy" Jokes Causes Controversy

I wrote a few gateway (protocol conversion) applications in assembly, and they were full of fun names and labels.

cp BeenWaiting, aWhile
brge CallTheBitchAgain

cp BeenWaiting, FuckingForever
brge WeGotFucked
CallTheBitchAgain: // because XYZ can't write a scheduler that works
decr TXbyteCounter
jmp RequestPacket

WeGotFucked: // because losing the state of a connected peripheral when they're too busy is an acceptable practice to some
jmp BandAidRestart
jmp ConnectWithKey

Comment: Re:You're doing it wrong. (Score 1) 166

by EETech1 (#49311755) Attached to: Internet of Things Endangered By Inaccurate Network Time, Says NIST

It's incredibly precise, I used to test ECU software to 12,000 RPM. That's 200 Revolutions per Second, or 72,000 Degrees per Second.

At 33Mhz, you have about 458 clock cycles per degree, so if you have a 60 tooth crank sensor with 6 degrees per tooth, you have a real time position update you need to task switch to, synchronize with, and schedule events on coming every 2750 clock cycles. In between them, you have to read filter and diagnose all of the sensors so you can look up, interpolate, and calculate all of the fuel and spark info, convert it back to binary time counts, then load or reload all of the different hardware timers safely at the proper time so they don't skip or wrap around.

You have to have over 7200 events (start and end of: fuel, air, spark on a 6 cyl, low emissions 2 stroke) happen at the exact time every second or the engine will misfire.

Starting with the Motorola MPC555 there was also a TPU (Time Processing Unit) that had multiple "self-synchronizing" counters and timers you can daisy chain, that took care of most of the heavy lifting (besides scheduling it!!!)

The TPU, along with a PowerPC core or two now allows modern ECUs to calculate everything based on a Simulink model of the engine while all of this is going on.

Comment: Re:Dupe (Score 1) 840

I did a starter on a Chrysler 300M, and if you didn't want to take the exhaust and the motor mount off, you can take the solenoid off, then take off the starter motor from the snout, then take the snout off the block, and get it out in like 20 pieces.

After all that bull I really didn't want to put it all back together (paper clips in the brushes, shims on the shaft where I can't see) even though all I found was just a corroded steel on copper washer in the solenoid. I cleaned it up, and greased it up and put it back together, it seemed to work fine and it is still working 5 years later.

A new starter was outrageous, and the labor was even worse.

Funniest part was my friend watching me come out with piece after piece, I know she was wondering how it was ever going to go back together again, or if it was going to just crap out on her again (really a rusty washer??? All those pieces??? Should I just have it towed???)

Comment: Re:Its a cost decision (Score 1) 840

There's this glue called goop (not that goop from the hardware store) that they have at hobby stores that will hold aluminum tubing to nitro-methanol and oil soaked fiberglass. We used to use it for model boats and it would hold anything, to anything. It took a long time to set but it held on forever after that.

Comment: Re:Its a cost decision (Score 2) 840

1. Hook Up oscilloscope
2. Start Engine
3. Look at oscilloscope
4. Replace Or Rebuild correct part

If you have to make #1 from an Arduino and a couple of resistors, bonus points for you.

If you release the resulting #1 as Autoduino or Alternatoduino on github it's a double bonus.

Triple bonus for a YouTube vid.

Comment: Re:Dupe (Score 1) 840

I used to do the fuel injection on these:

With all the instrumentation (EGT AFR Knock etc) we had to have to monitor and calibrate three of these, changing out 24 knock transducer spark plugs with piezo cables on them while worrying about scratching a $200,000 paint job on someone's boat, with everything hot after running wide open for an hour, has my vote for biggest PITA.

Hint: The easy way is pulling the front two motors out, but it's hard to do that floating somewhere.


"It's ten o'clock... Do you know where your AI programs are?" -- Peter Oakley