Tach output question

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masterx81
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Tach output question

Post by masterx81 »

Ho to all...
I need one info on the msns-e code...
When the ecu 'fire' the tacho out? at what engine angle? 0 (or 360) ?

Thanks!
jsmcortina
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Post by jsmcortina »

At the same time as it receives (or decodes) a tach trigger, it is turned off 1ms (from memory) later.

James
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Peter Florance
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Tach output question

Post by Peter Florance »

I was thinking the tach input is an edge-triggered interrupt. If so, it would seem to be plenty of time to trigger.
 
What a great idea!
 
Peter Florance
Owner - First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org (peter@firstfives.org)
ssr# 284
----- Original Message -----
From: Mike_Robert (pmrobert@adelphia.net)
To: megasquirt-mss@msefi.com (megasquirt-mss@msefi.com)
Sent: Sunday, May 21, 2006 8:33 AM
Subject: Tach output question



jsmcortina wrote: At the same time as it receives (or decodes) a tach trigger, it is turned off 1ms (from memory) later.

JamesJames, I haven't tried it yet - do you think that is enough of a pulse to trigger tach input on another MS? I'm thinking of using one MS running Extra for rotary ignition triggering another running MSII for hires fueling and AMC. I only have room for 2 injectors so they're rather large.
This scheme also gives me a bunch of outputs.

-Mike



This post is at: http://www.msefi.com/viewtopic.php?p=121289#121289
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masterx81
Master MS/Extra'er
Posts: 776
Joined: Mon Oct 25, 2004 7:36 am
Location: Asti - Italy

Post by masterx81 »

jsmcortina wrote:At the same time as it receives (or decodes) a tach trigger, it is turned off 1ms (from memory) later.

James
So, is maintained high for 1 ms, but at 8000 rpm, there is a tach every 1/8000 = 0,125ms, right?
How it can maintain the tach high for 1 ms if for tach to tach there is 0,125ms?

Or my math is bad?

Thanks!
masterx81
Master MS/Extra'er
Posts: 776
Joined: Mon Oct 25, 2004 7:36 am
Location: Asti - Italy

Post by masterx81 »

Whops, forgot rpM(minute) :-)
SORRY !!!!
Peter Florance
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Tach output question

Post by Peter Florance »

I suspect that the caps will need to be removed.
I wonder if I can test this with square wave generator at 2Khz?
 
 
Peter Florance
First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org (peter@firstfives.org)
ssr# 284

From: Mike_Robert [mailto:pmrobert@adelphia.net]
Sent: Sunday, May 21, 2006 11:39 AM
To: megasquirt-mss@msefi.com
Subject: Tach output question




No prob, masterx81, I'm glad you started this thread - though I apologize for the partial hijacking of it! Peter, I was more concerned about the effects of D1,D2, R12, C30 & C12 on that skinny 5v pulse. Due to the combined voltage drops of D1 & D2 and no obvious need for them in my proposed application, I'm probably going to jumper them right off the bat. I think the v3 instructions have you not installing all of the above but I don't have access to the board right now so am not sure. I'm just looking to make sure that the pulse will fire that opto reliably.

-Mike



This post is at: http://www.msefi.com/viewtopic.php?p=121312#121312


Posted by email.
Peter Florance
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Posts: 3653
Joined: Fri Apr 02, 2004 8:40 pm
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Tach output question

Post by Peter Florance »

I would just drive the VR input. I suspect that would work fine.
 
Peter Florance
First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org (peter@firstfives.org)
ssr# 284

From: Mike_Robert [mailto:pmrobert@adelphia.net]
Sent: Sunday, May 21, 2006 11:39 AM
To: megasquirt-mss@msefi.com
Subject: Tach output question




No prob, masterx81, I'm glad you started this thread - though I apologize for the partial hijacking of it! Peter, I was more concerned about the effects of D1,D2, R12, C30 & C12 on that skinny 5v pulse. Due to the combined voltage drops of D1 & D2 and no obvious need for them in my proposed application, I'm probably going to jumper them right off the bat. I think the v3 instructions have you not installing all of the above but I don't have access to the board right now so am not sure. I'm just looking to make sure that the pulse will fire that opto reliably.

-Mike



This post is at: http://www.msefi.com/viewtopic.php?p=121312#121312


Posted by email.
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