Dual 7-Segment LED Display

[erice1984]

between shifts at higher rpm most engines will knock a little bit, also tapping near the sensor to get a response. The engine is a 4G63 motor in my friends EVO 8.

Reason for the seg-LED is this is all he wants on it. Also it is smaller than using LCD, I know code is going to be longer but I guess that is a trade off, and all the PIC is going to be used for.

8MHz clock isnt fast enough?

[skimask]

between shifts at higher rpm most engines will knock a little bit, also tapping near the sensor to get a response. The engine is a 4G63 motor in my friends EVO 8.

Reason for the seg-LED is this is all he wants on it. Also it is smaller than using LCD, I know code is going to be longer but I guess that is a trade off, and all the PIC is going to be used for.

8MHz clock isnt fast enough?

EVO 8 - not going to spend much time doing part-throttle acceleration is it?
8Mhz not fast enough? - most likely not, but I think your main limitation is going to be the speed of the A/D converter.
Are you tapping into the existing knock sensor line? Can you tap on the block and watch the timing back off or what?

[erice1984]

thats the interesting part, if you grab a screw driver and tap very close to the sensor it picks up small stuff, drop the hood closed about 18" up and you will see readings.

and yes, tapping into the exsisting signal wire.

What if it was run at 20MHz ?

Yeah he doesn't spend much time at part-throttle, mostly easy driving, but on ramps and such its WOT. Same with me usually, I got a swapped GC Impreza (2000 2.5rs) with a 2002 wrx motor (EJ205) Did all the wiring myself so I have mastered diagrams, not to mention I am going to school for auto engineering, and already graduated from UTI auto technician.

[skimask]

thats the interesting part, if you grab a screw driver and tap very close to the sensor it picks up small stuff, drop the hood closed about 18" up and you will see readings.

What are you measuring with?

[QUOTE]What if it was run at 20MHz ?[QUOTE]
A/D converter speed doesn't care about oscillator speed, well, not really. The A/D converter will only run as fast as it will run, doesn't matter how fast you run the oscillator.
The older A/D converters will 'only' run at about 20ksps, the new ones around 100ksps. Problem is, once you get up to those speeds, you're going to need good filtering at the front end.

Yeah he doesn't spend much time at part-throttle, mostly easy driving, but on ramps and such its WOT.

What I meant was, it's an EVO-8...probably a hot rod, street racing, etc.etc...

So, write some code, try it out, see what happens, come back with questions....

[erice1984]

A/D converter speed doesn't care about oscillator speed, well, not really. The A/D converter will only run as fast as it will run, doesn't matter how fast you run the oscillator.
The older A/D converters will 'only' run at about 20ksps, the new ones around 100ksps. Problem is, once you get up to those speeds, you're going to need good filtering at the front end.

Thats the problem, I know that is kilo samples per second, but as far as filtering I am lost. I have never had to deal with this stuff before.

thanks.

[skimask]

I have, just dont know how to interpret the signal, was looking for suggestions, and I have some code written for display etc.

thanks.

Well, what does your baseline (no knocking) signal look like?
What does your knocking signal look like?
I know what they 'should' look like according to the books, but what do YOUR signals look like, with YOUR input circuit, filters, etc.
Post some 'scope pictures or something...

[erice1984]

Wish I did have a pc o-scope, and my friend lives 1000 miles from me, so I am waiting on him.

These sensors arent that accurate in the first place. but I guess I am waiting on him to get me some info on what the waveforms look like and what knock looks like with engine running and not running.