LED revcounter for 98 m900

[Big Troubled Bear]

Hi, I want to build my own LED revcounter for my monster m900, must have 10 or 12 LED display plus 3 7 segment led displays.

I have searched the net to no avail, maybe there are people out there that have gone this route and could maybe help me out with some circuit diagrams

[ScottRNelson]

What are you trying to accomplish, besides adding some pretty lights to the bike?

I've ridden Ducatis with LED tachometers and felt that it was worse than no tachometer at all.  Seriously.

They're not accurate enough for things like fine-tuning the idle speed and don't even work that well to tell you how close you are to redline either for accurate shifting.  Those are the only two things I've found that require a tachometer.  In the mid-range you can hear and feel all you need to know about your engine.

When I start either of my bikes, I like to adjust the fast idle (i.e., "choke" lever) so that the bike is idling about about 1400-1500 rpms while the engine warms up a bit.  Your LEDs won't be that accurate.  You'll be lucky if you can tell the difference between 1500 and 2000 rpms.

For hard acceleration, I look at the tach to try to shift before I hit the rev limiter.  On the older Monsters, there is no rev limiter, so you can feel when it's time to shift.  I put a tachometer on my 1997 M900, but I wouldn't bother if I had another one.

So, are you after accuracy, or just pretty lights?

[bigiain]

Hi, I want to build my own LED revcounter for my monster m900, must have 10 or 12 LED display plus 3 7 segment led displays.

I have searched the net to no avail, maybe there are people out there that have gone this route and could maybe help me out with some circuit diagrams

Where are you starting from? How much electronics do you know? How's your programing? I'm pretty sure the solution you seek is as much software as circuit diagrams... You could probably make an analog circuit to drive just a strip of led's (I'm pretty sure that's how the old DP tach works), but of you want to drive 7 segment displays too, you're out of the analog realm.

I've got a pair of stepper motors and some darlington arrays and microcontrollers spread out on the kitchen table (and annoying the girlfiend) at the moment where I'm investigating a similar project. I'm thinking of digitally driven analog style speedo and tach myself, but at least half the job would be the same for an LED strip type tacho.

If you want some hints about where I'm finding useful information, I'm basing my stuff around an Arduino board (http://arduino.cc/), and stealing ideas about optoisolated rpm sensing from the microsquirt guys (http://microsquirt.info/), and I found some programming ideas and hall effect sensor info here (http://www.piclist.com/techref/piclist/biketut/index.htm)

A couple of things that initially strike me about your spec - you're initially wanting 33 drive pins (12 leds plus 3 * 7 segment leds) - that's getting too many for most small microcontrollers, which means you're going to have to complicate things or "cheat". There are some obvious easy "cheats" first - the Monster doesn't really need 3 full digits of tacho, even if you are wanting to measure past 10,000rpm, that leading digit is only ever going to be blank or "1", so you only need one line to drive that, that'd then let you display 0-19900 rpm in 100 rpm increments using only 15 output pins. That's still not quite enough though for small microcontrollers - the ATmega168 I'm using only has 14 digital out pins plus 6 analog pins which can be abused into working as digital outputs if required - but that leaves you with only 5 pins left to drive the led bar display. You then could either complicate the design by using the 5 remaining pins as a binary number through a demultiplexer to drive the led bar (which could give you 31 leds in the bar, or perhaps 15 leds and a shift light), or you could cheat some more and hard wire the 7 seg display of the lowest digit to only show "0" or "5", which means you could drive the digital display with 9 pins and get 0-19500rpm in 500 rpm steps, leaving 11 pins to drive the bar graph...

Which set of compromises do you want to make today? 

big (Oh, and +1 to Scott's observation that a Monster really doesn't need a tach...)

[Big Troubled Bear]

So, are you after accuracy, or just pretty lights?

Some pretty lights I suppose

I used to work in the avionics industry a while back and some of the riders out here with older ducati`s like the the old DP style tach ( myself included ) just thought that I would be able to build something myself, I have build a revcounter with 2 7 segment led displays and bench tested to 9900 rpm just thought that adding a extra segment would look better + green to red bar graph would act as shift lights

[ScottRNelson]

If you can keep it green until 8000, then go yellow there and red at 8500, with maybe two red ones at 9000, it might actually be useful.

I don't know if we've been any help, but if you make one, you need to take a video of it while revving the heck out of your engine.  If it looks good enough, maybe other forum members will try to talk you into making one for them. 

[Big Troubled Bear]

Have found circuit diagram for bar graph with 10 leds will build and test