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### Topic: Motorcycle Aux Info Center(AIC) - Interface Questions (Read 1 time)previous topic - next topic

#### Red_Rider

##### May 05, 2011, 12:22 am
Hello everyone -

I'm just a Noobe hacker here who's retired and likes to play with electronics and motorcycles.

Using an Arduino 5v Pro Mini, I'm prototyping a motorcycle Auxiliary Info Center (AIC) with the following functions:
1. Gear Position Indicator (using voltages from a gear position switch)
2. Analog and digital tach display (using pickup from Engine Digital Control ECU thru an opto isolator)
3. Electrical Voltage Monitoring & Over / Under Warning (use a voltage divider to scale input range from say 0-15vDC to 0-5vDC)
4. Engine coolant temp (voltage from engine coolant switch using another voltage divider if the switch isn't 5vDC)
5. Gear Shift Point Indicator (Calculated)
6. Ambient Air Temp & Calculated Wind chill when temp is below 50 degrees F.

I'm using two types of displays for the info:
7. A two 1" Alphanumeric Blue LED's w/ alphanumeric drivers - one LED for gear indication (N & 1 through 5) and one LED to simulate an analog tach display
8. A two line back lit serial LCD display module for all other info

I have items 1-3 prototyped using bench top voltages for and a dual 555 pulse generator circuit for but now need help with interfacing the 5v arduino prototype with a real world motorcycle.

I've read a lot but would appreciate any help with interfacing my motorcycle's 12 vDC to the arduino's 5 vDC input power?
The Motorcycle's electrical system isn't as noisy as a car's and doesn't have all the current / voltage spikes as in a car.  The motorcycle generator's voltage varies with RPM's and also with the current battery state - ranges from say around 10 - 14.5 vDC.

What should I do?

For power to Arduino:
9.  I am told to use a series resistor to limit current after an in-line 1amp fuse - what value and power rating fpr the resistor?
10. I also read I might need to provide a separate voltage regulator to step down from 12 vDC to a lower voltage to avoid overheating the arduino's power linear regulator?
11.  Or would just a clamping zener diode and a capacitor be enough?  (What values/rating would I need?)
12.  Or should I use "transorb" whatever that is?  (Never heard of this - what spec?)

For input signal interfacing:
13.  For the tachometer signal, I plan to use an optical isolator chip but I'm not sure yet what the voltage is for the firing signal from the engine control unit to the spark coil.  Would an inductive pickup be simpler - just some wires coiled over the spark plug wire to an opto isolator?
14.  For the 12vDC monitor, the gear position, and the engine coolant temp  monitor, I am planning to use just a simple resistor voltage divider to rescale the analog voltages between 0-5vDC?

Space is tight in the double stacked proto board and enclosure so the simplest design would be best for me.

Just FYI - I learned machine language programming in front of a computer with:
- toggle switches for direct binary entry into three 19 bit registers for troubleshooting
- a 20-40 card per minute card reader that usually crashed every 3000 cards or so - each card had one machine language instruction - It wasn't unusal to have 200 - 4000 cards (or lines of code) in a program
- an IBM 5 character per sec integrated ribbon style typewriter
- a 60 line per minute form fed hammer style line printer which broke regularly from the mechanical banging!
- 8K core memory in two six foot high enclosures
- a separate 6 foot high enclosure that housed electronics for double precision arithmetic calculations
- two 360K disc drives (36" diameter discs spinning inside a six foot high enclosure containing a slight vacuum

So - I'm absolutely ecstatic working with the Arduino platform!!

Any help on my motorcycle project would be awesome!!

Greg

#### PaulS

#1
##### May 08, 2011, 06:37 pm
Quote
The Motorcycle's electrical system isn't as noisy as a car's and doesn't have all the current / voltage spikes as in a car.

Got any facts to back up this statement? If anything, I'd expect that a motorcycle electrical system to be noisier than an automobile's, since most motorcycles don't have radios and other things that require quiet power to function well.

Quote
The motorcycle generator's voltage varies with RPM's and also with the current battery state - ranges from say around 10 - 14.5 vDC.

Most car systems have tighter tolerances - more like 12 to 14.5.

With a decent heat-sink, creating a stable 5V source using a 7805 regulator shouldn't be too difficult.

Quote
9.  I am told to use a series resistor to limit current after an in-line 1amp fuse - what value and power rating fpr the resistor?

That depends on what voltage drop you are trying to achieve, and how much current is behind that voltage.

Quote
I also read I might need to provide a separate voltage regulator to step down from 12 vDC to a lower voltage to avoid overheating the arduino's power linear regulator?

Certainly a good idea.

Quote
14.  For the 12vDC monitor, the gear position, and the engine coolant temp  monitor, I am planning to use just a simple resistor voltage divider to rescale the analog voltages between 0-5vDC?

Is this a question or a statement?

#### Red_Rider

#2
##### May 09, 2011, 11:35 pm
Paul -

Thanks for the ideas - this is my first Arduino project and I'm still learning a lot about electronics.

1.  I'm told that the electrical systems on newer motorcycles are less noisy because they don't have all the relays, inductive stuff, and other switched currents that a car does - but I don't have any actual measurements.  On my M/C - 2009 Suzuki w/ EFI - the fuel injection system is quite simple and the spark system to the plugs also takes a relatively low voltage signal to a coil that is almost on top of the spark plug.  The only other electrical loads are lighting & horn which I guess could cause load spikes.

The AIC I'm designing isn't mission critical so if it drops out due to low voltage during start up, I'm ok. I'm not planning on using any volatile memory at this point either.

2.  The voltage range I'm using 10-14.5 vDC is more for monitoring the voltage condition of the battery and charging system.  Below 11 vDC is essentially a dead battery.  And during high RPM's, the voltage can get up to the 14.5vDC from the charging system I'm told.  Nominal operating voltage is between say 11.5 - 12.5 vDC I'm guessing when the engine isn't running.

3.  The series resistors was a suggestion from someone just to limit maximum current spikes since the fuses are so slow to blow - a Zener would probably be better.

Item 14 was more a statement.  However, I find out the gear position sensor is operating in the 0-5vDC range and maybe so will the coolant temp sensor.  Both would simplify things but I'd probably do something just to protect the Arduino inputs from higher voltage spikes due to fumbling idiots reversing wiring while fooling around.  (Don't ask me why I know about this!!)

Thanks again and any further suggestions are appreciated!!  I'll post more as the project progresses.

Greg

#### 2Wheeler

#3
##### Jun 18, 2011, 04:44 am
Greg,
Any updates to this? Like you, I'm new to Arduino and trying to soak up as much as possible. I have another thread here about a motorcycle dash.

I have used digital and analog voltmeters on two of my bikes- '06 Concours & '81 GS1000. The Concours would go over 14V on occasion- maybe up to 14.2 as I recall, but was usually in the 13.9 range. The Suzuki sits right on 13.8 after about 1500 RPM, and will drop under 11 at idle. Seeing as how mine is decades older than yours, perhaps things have changed.

My latest project is making a replacement dash for an '85 Honda Sabre. I'd be interested in seeing your progress, since some of what I'd like to do is similar. My dash will have all of the OEM functions:
Speed
RPM
Fuel level (with LOW FUEL warning)
Coolant temp
Gear position (my bike uses a 7 wire setup, grounding pins as each gear or neutral is selected)

All of my senders are old school resistance ones. I'm planning to update them to the common/modern 5V ones, except for the fuel level. My speedometer is an oddball- most bikes of this era were cable driven but this one used an early 3 wire sensor: 8V in, ground, and 0~4 to 8V out. I think it works the same as the newer 12V senders from what I've read. My tach worked off the (-) side of the coil.

Plus warning lamps:
Oil pressure
Tail light out
High beam
Neutral

I want to add some more monitoring:
Oil pressure
Oil temp
Ambient temp w/ ICE warning below 35 degrees (that wind chill calc you mentioned sounds neat)
Volts

I'm planning to use the 18B20 temp sensors for all temp functions- planning to encase two in brass pipe plugs & epoxy them like the newer sensors.

There appear to be a few of us here doing stuff with bikes. Looking forward to seeing your progress.

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