Is there any way one can get a reading of the advance setting. would a calibrated voltmeter on the SAW pulse line work ?
Any other more elegant ways of displaying advance without needing to plug in a laptop would be nice.
Thanks
Steve
Advance display
Moderators: JeffC, rdoherty, stieg, brentp
See when driving?
Presumably you want to be able to see the advance whilst driving - so a strobe light might be a non-optimal solution?
Depends on the level of geekness and lateral thinking you're willing to adopt:
- low geek method - yes, measuring DC voltage on SAW will give an indication of advance (lower voltage == higher advance) So I guess you could calibrate a voltmeter to indicate advance. HOWEVER, you'ld have to calibrate it at every rpm you're interested in, since measured DC voltage will increase as RPM anyway (since you get more SAW pulses per unit time as RPM increases), as well as decreasing with increased advance
- medium geek method - use Hyperterminal on a Pocket PC with a serial connection, send 'S' commands manually and decode the returned byte string
- high geek method - write some software to run on a Pocket PC with a serial connection, that sends 'S' commands automatically, decodes the returned byte string and shows a nice display of advance
- very high geek method - use a timer/counter that can measure pulse widths on a repeating signal to 1uS resolution. Again you have to calibrate measured pulse width to advance, but that's just maths. This method is RPM independent. I've done this with a s/h timer/counter from eBay (about 15GBP), but you need a battery powered unit or an mains inverter in the car if you want to drive at the same time
- extremely high geek gactor - same as above, but using an oscilloscope (yes, I've driven down the road watching pulses from in-car systems (not MJLJ) on a dual-trace scope running off a mains inverter in the lighter socket!)
- off the scale geek factor - design and build a microcontroller-based system that measures SAW pulse width and repetition frequency to derive advance and rpm. Show results on a cheap LCD character-based display. I've done this one as well - and very good it is too! Maybe I'll publish it one day...
Depends on the level of geekness and lateral thinking you're willing to adopt:
- low geek method - yes, measuring DC voltage on SAW will give an indication of advance (lower voltage == higher advance) So I guess you could calibrate a voltmeter to indicate advance. HOWEVER, you'ld have to calibrate it at every rpm you're interested in, since measured DC voltage will increase as RPM anyway (since you get more SAW pulses per unit time as RPM increases), as well as decreasing with increased advance
- medium geek method - use Hyperterminal on a Pocket PC with a serial connection, send 'S' commands manually and decode the returned byte string
- high geek method - write some software to run on a Pocket PC with a serial connection, that sends 'S' commands automatically, decodes the returned byte string and shows a nice display of advance
- very high geek method - use a timer/counter that can measure pulse widths on a repeating signal to 1uS resolution. Again you have to calibrate measured pulse width to advance, but that's just maths. This method is RPM independent. I've done this with a s/h timer/counter from eBay (about 15GBP), but you need a battery powered unit or an mains inverter in the car if you want to drive at the same time
- extremely high geek gactor - same as above, but using an oscilloscope (yes, I've driven down the road watching pulses from in-car systems (not MJLJ) on a dual-trace scope running off a mains inverter in the lighter socket!)
- off the scale geek factor - design and build a microcontroller-based system that measures SAW pulse width and repetition frequency to derive advance and rpm. Show results on a cheap LCD character-based display. I've done this one as well - and very good it is too! Maybe I'll publish it one day...
I think, steve, you're
I think, steve, you're referring to something you can visually monitor while you're driving, without having to have your laptop wobbling there on the passenger seat? I'm with you there. 
I'm liking the idea of an small module that can display the runtime variables on the dash as you drive. What interest would there be in such a beastie?
Brent
I'm liking the idea of an small module that can display the runtime variables on the dash as you drive. What interest would there be in such a beastie?
Brent
i would take one
i would take one
You've got it spot on
You've got it spot on Brent.
I was refering to,say, an LCD display that sits permanently on the dash to show actual degrees of advance
that the Megajolt is defining in real time and whilst driving. Ie, not having to have the laptop connected
or using strobes on the pulley wheel.
Thanks for the ideas, can anyone help with a design to do this efficiently - or Brent is it possible for
the microprocessor in the Megajolt to drive an off-the-shelf (say maybe from RS Components or Maplins - UK,
or Digikey USA) LCD counter/timer directly?
Thanks
Steve
I was refering to,say, an LCD display that sits permanently on the dash to show actual degrees of advance
that the Megajolt is defining in real time and whilst driving. Ie, not having to have the laptop connected
or using strobes on the pulley wheel.
Thanks for the ideas, can anyone help with a design to do this efficiently - or Brent is it possible for
the microprocessor in the Megajolt to drive an off-the-shelf (say maybe from RS Components or Maplins - UK,
or Digikey USA) LCD counter/timer directly?
Thanks
Steve
Megavew for Megajolt???
I have seen something similar for use with the megasquirt set-up. This one actually allows the user to change settings. Here is the link:
http://www.bgsoflex.com/mv/megaview.html
Seems someone should be able to make it work for megajolt, I assume it would be simplier than the megasquirt system.
http://www.bgsoflex.com/mv/megaview.html
Seems someone should be able to make it work for megajolt, I assume it would be simplier than the megasquirt system.
in car reatime display
Hi, I'm an AVR (bascom) programmer - is there somewhere I can find out the commands I need to send MJLJ v3 on the existing 232 port so I can read MAP, RPM and advance values? With this info, I could do a realtime display...
Julian Spink
I'll post something
I'll post something later....
..but in the meantime, if you've got a MJLJ connected on the RS232 and a copy of Bray's Terminal then you can send a 'S' to the MJLJ and you get six(?) bytes of status info back which allow you to determine:
- current advance
- curent MAP/TPS value
- current RPM
- the x,y "co-ordinate" of the base current bin in the map that the advance is being derived from
..but in the meantime, if you've got a MJLJ connected on the RS232 and a copy of Bray's Terminal then you can send a 'S' to the MJLJ and you get six(?) bytes of status info back which allow you to determine:
- current advance
- curent MAP/TPS value
- current RPM
- the x,y "co-ordinate" of the base current bin in the map that the advance is being derived from
Hi, Yes- the megaview could
Hi, Yes- the megaview could be adapted to work with the MJLJ. It might be a bit of overkill with the processor they're using, but it would certainly work.
Regards,
Brent
Regards,
Brent
run-time display
I do not see much value in this dash display idea. Just another dashboard frill. However, as I have communicated before, an accurate voltage in the 0-5 range, indicating advance, would make logging a breeze. When coupled with the other dynamically changing engine operation parameters, the information would be helpful. Then everyone that wants another display could use a volt monitoring gauge from any number of sources or DIY. A ten factor would be nice. 1V = 10 degrees, 3V = 30, etc.
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minicooper
- Posts: 8
- Joined: Wed Nov 30, 2005 9:07 pm
what would be involved in
what would be involved in coverting the megaview system to work with the MJLJ?