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geoffct wrote:Thanks for the tips Bruce, I think I may simply replace that 100k with 47k. One of the team members does smd rework everyday, so swapping resistors is nothing at all. Could we go lower than 47k ohm?
Also could you verify which resistor I need to replace on this diagram? I thought you were referring to R54, but that is already listed as 47k. Are these the latest schematics?
Thanks Again,
Geoff
Yes, it is R54. You can go lower than 47K but this will lead to even more negative voltage for the hysteresis reset. If you want to go low, you can do 10K or even lower. With your waveforms I think you will still be OK during cranking.
Well, the hysteresis resistor worked... sort of we are now running about 13kohms, and read rpms consistently while cranking, but we loose those rpms as soon as the engine kicks over. We initially thought this was a fuel or spark issue, but the rpms drop to zero.
On the scope we don't appear to have any erroneous teeth, but they would only appear on the stutter, so accordingly they would be hard to see. I have searched a lot and haven't seen anything.
Can you try the attached code. What this code does is similar to the % mask with a coil ignition, where any tach inputs < x% od time between tach inputs are thrown out - to get rid of coil ringing. Your VR input is somewhat similar based on your scope shot, except there is only one tiny ring. But in this case the code throws out any "tooth input" that comes in sooner than PulseTol % of teh last time between teeth. The base code has always done this, but only for 1 or 2 consecutive teeth - then it declares lost synch. The attached code keeps doing it no matter how often it happens. If this works we will put it in as an official option. To best use this set all 3 of the PulseTols (crank, after start and normal running) to 50 %. You can then tune from there. You don't have to change your ini or msq as it is the same as the latest 2.883j except for the change I mentioned.
I am still not running. The tach works fine while cranking, but once it kicks over and starts to run under gasoline power, we lose tach (reads zero rpms momentarily) and it stalls back into cranking.
I am really lost. It doesn't appear to be a crank signal conditioning issue any more. Could it be a software config issue? I have tried adjusting the next pulse tolerance, but to no success.
Is there a way to log exactly what the uS is "thinking"? I would like to write to the log file when it sees a pulse too soon, or misses one, etc.
I appreciate any help and guidance, but I must admit that if I cannot solve this issue in the next week or so I will have to abandon my use of microsquirt in favor of another ECU.
- deltaT: the time delta (interval) between rpm pulses in microseconds.
- trigger±: The code for toothed wheels checks for missing or extra teeth and handles them if they occur, but only allows one or 2 corrections in a row. More than this and it re-synchs. This will tell users when they have noise or weak signal issues.
- tachCount: counts tach pulses for use in correlating datalog values with tach pulses (at lo rpm).
These might be what you are lookng for. They are standard in the datalogs for 2.883j code.
- deltaT: the time delta (interval) between rpm pulses in microseconds.
- trigger±: The code for toothed wheels checks for missing or extra teeth and handles them if they occur, but only allows one or 2 corrections in a row. More than this and it re-synchs. This will tell users when they have noise or weak signal issues.
- tachCount: counts tach pulses for use in correlating datalog values with tach pulses (at lo rpm).
These might be what you are lookng for. They are standard in the datalogs for 2.883j code.
Lance.
Lance is correct. Especially the trigger± variable, this is a real indicator of incorrect sync...
Disregard this post, well most of it, I had a bit of a configuration issue.
Sorry for the delay, but I have started work on another ECU option. I couldn't find the tachcount display, nor could I see the Trigger+/- in the logs, but the delta T is working.
The Trigger+/- display, never registers an extra or missing pulse except on blipped start switch (normal I would expect)
I created a log file so you can see what I can see.... I would love to have made some "misinformed person" mistake, but I don't see it here.
Thanks Again,
Geoff
Last edited by geoffct on Mon Mar 24, 2008 3:17 pm, edited 1 time in total.