View unanswered posts | View active topics It is currently Sat Jun 23, 2018 8:54 am



Reply to topic  [ 5 posts ] 
RPM input schematic 
Author Message
1N4001 - Signed up
User avatar

Joined: Tue Jun 10, 2008 5:17 pm
Posts: 1607
Should we use a simple Hall input for this first round here? If so this part of the schematic is easy, three wires, on is the hall output going to the ECU.

My preference would be to keep the VR signals as short as possible to keep the antenna's minimal. Then run a hall like signal to the ECU. So I really don't think we want the VR in this part of the design.

When doing a hall, I know the sensors I have are 12V compliant. Are the typical automotive hall's the same? Or do they sometimes require current or voltage conditioning?


Thu Jul 31, 2008 12:52 am
Profile
Moderator
User avatar

Joined: Tue Jan 15, 2008 2:31 pm
Posts: 15143
Location: Home sweet home!
I'm not sure, but I think you will find that everyone wants their VR stuff on board. LM1815 is the way forward for that IMO.

We want two inputs to the cpu for this, either of which or both can come through the LM1815s or not. that way a user can have an opto and a hall, an opto and vr, a vr and hall or two of any of them. If not required for a hall/opto user the lm chips can be left out.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Thu Jul 31, 2008 8:52 am
Profile WWW
1N4001 - Signed up
User avatar

Joined: Tue Jun 10, 2008 5:17 pm
Posts: 1607
I was picturing the VR could spike back, but I really don't know much about the LM1815. I'm still reading / re-reading the data-sheet. That is why I was picturing the opto. I figured it we put in an opto, then why not put it close to the MCU, so protect both. Probably not required for either, also we have the digi-protect circuit, so that probably takes care of those spikes anyhow.

I'll put the VR kind of in parallel with the hall input.


Fri Aug 01, 2008 1:48 am
Profile
Moderator
User avatar

Joined: Tue Jan 15, 2008 2:31 pm
Posts: 15143
Location: Home sweet home!
I think you should use the same trace coming in. That way the instructions are the same and no pins are wasted. If it's a VR signal you put the chip in. If it's a Hall signal you don't and just install a jumper from vrin pin to square out pin. Up to you though I guess.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Fri Aug 01, 2008 1:55 am
Profile WWW
1N4001 - Signed up
User avatar

Joined: Tue Jun 10, 2008 5:17 pm
Posts: 1607
That's exactly what I meant by in parallel. So we're on the same page here.


Fri Aug 01, 2008 2:35 am
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 5 posts ] 

Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software for PTF. ColorizeIt.