Jump to content

Archived

This topic is now archived and is closed to further replies.

BiKenG

Gear Position Indicator

Recommended Posts

This may seem a dumb question, but how does the GPI work on the VFR1200F?

 

By which I mean, what does it display when in Neutral. Is that with the engine running?

 

If you turn on the ignition but don't start the bike and put it into gear, does the GPI show that gear position? And if you change through the box, does the GPI display the correct gear, even with the engine not running?

 

Of does it only display the selected gear position when the engine is running?

Share this post


Link to post
Share on other sites

if the kill switch is off it won't display....

 

Share this post


Link to post
Share on other sites

There are two kinds of add on gear indicator + factory. The two add on units either use switches or rev detection. The GP ones use rev detection. The unit powers up with bike mains, it should read zero or N for neutral. When you start the engine it detects revs which it considers idle, as you select gears, it detects the increase & step decrease as you change up. This it takes as a new gear position. The logic in the chip then tries to keep track of the gears as you change up/down & indicate accordingly.

Share this post


Link to post
Share on other sites
9 hours ago, lshark said:

if the kill switch is off it won't display....

 

Aha, you may have hit the nail on the head there. The kill switch was off so that may be what's confusing me. Hopefully that's all it is. I'll go and check...

Share this post


Link to post
Share on other sites
8 hours ago, Mohawk said:

There are two kinds of add on gear indicator + factory. The two add on units either use switches or rev detection. The GP ones use rev detection. The unit powers up with bike mains, it should read zero or N for neutral. When you start the engine it detects revs which it considers idle, as you select gears, it detects the increase & step decrease as you change up. This it takes as a new gear position. The logic in the chip then tries to keep track of the gears as you change up/down & indicate accordingly.

 

You really should know me better than that by now.:wink:

 

 My question concerns the OEM GPI on the VFR1200 that needless to say is not simple. The ECU reads the sensor (one wire for each gear) and then it sends the information to the dash within its serial communication link. So it could send anything at any time and Honda may have decided it wanted no display when the engine is not running, or as is apparently the case, when the kill switch is off.

 

Watch this space...

Share this post


Link to post
Share on other sites
19 minutes ago, BiKenG said:

The ECU reads the sensor (one wire for each gear) and then it sends the information to the dash within its serial communication link. So it could send anything at any time and Honda may have decided it wanted no display when the engine is not running, or as is apparently the case, when the kill switch is off.

Yes, that is correct Ken. When the engine is off it does not display N but a single dash.

 

It sends the data using only one wire TXD(send) - I made a sniffer for that line with my Arduino and I was able to read some data.

Never bothered to encrypt that data tho.

Share this post


Link to post
Share on other sites

lshark nailed it. Once I flipped the kill switch to ON, the GPI is working perfectly.

 

My problem is trying to figure out why certain modifications, or combinations of kit do not seem to be working when I don't have an original bike to compare it to. So thanks.

Share this post


Link to post
Share on other sites
24 minutes ago, veeefour said:

It sends the data using only one wire TXD(send) - I made a sniffer for that line with my Arduino and I was able to read some data.

Never bothered to encrypt that data tho.

 

Ah Prez by another name I assume :unsure:. Hi

 

Interesting about the sniffer. Were you able to decode the serial protocol? How easy/hard would it be to make a converter to RS232?

 

A moot point maybe as I have given up trying to do that in order obtain HISS, Oil pressure, FI, GPI etc signals to my Race Tech Dash2 Pro. I have instead opted to utilise a CrossTourer dash which not only fits in well, but immediately has access to all that data that I was missing. I had to figure out the wiring pin layout in the connector as the X is different from the F even though the connector and wires are all the same and had to confirm the X dash expects 12V to the indicator warning lights (it does). Then I had a bit of a worry yesterday when I saw the GPI wasn't working.

 

Now all that's left is a need to expand the 'span' of the fuel level sender output as the X has a greater span (resistance range). If it was the other way around it would be easy, this will take some thought, but can wait. I'll just use a resister to get it correct at empty, so Mohawk needn't worry about having to push me due to running out of fuel :biggrin:

Share this post


Link to post
Share on other sites

Hi Ken

I was able to read the data lines - they look similar to CAN lines but had different structure. Sure it's possible to convert those

lines to the "human" parameters but this would require some programming. That is exactly what Heal Tech done.

It's nothing really complicated if you know how to program an uC.

 

You can always re-scale any fuel sender(as it's simply a potentiometer) by adding the correct resistor in parallel. I'm sure you know the formula:

1/Rp= 1/R1+1/R2...

 

Prez

 

 

 

Share this post


Link to post
Share on other sites
1 hour ago, veeefour said:

Hi Ken

I was able to read the data lines - they look similar to CAN lines but had different structure. Sure it's possible to convert those

lines to the "human" parameters but this would require some programming. That is exactly what Heal Tech done.

It's nothing really complicated if you know how to program an uC.

 

You got me there. What has Heal tech done with serial comms like this?

 

Quote

You can always re-scale any fuel sender(as it's simply a potentiometer) by adding the correct resistor in parallel. I'm sure you know the formula:

1/Rp= 1/R1+1/R2...

 

No good, that's the wrong way. It is as you say, easy to reduce the span, but you cannot increase the span just with resistors. Try it. If you can do it, do let me and the rest of the world know 'cos everyone else thinks it is impossible.

 

I think it'll have to be some kind of special circuit that creates a varying resistance, based on the resistance of the fuel level sensor. But that'll have to wait. At least the 2012 bikes have a low fuel sensor, so I'll have that if nothing else. Most of my other bikes only have that reserve light anyway, so no real hardship.

Share this post


Link to post
Share on other sites

Heal tech works with diagnostic connector which runs on K-line single wire Honda specific transmission protocol which is nothing like CAN.

RXD and TXD are typical for serial communication(Recieve and Transfer) - those two are close but rather not compatible.

 

What VFR1200 gauge cluster has is only RXD - something very specific here.

 

Combining the resistors in parallel will never increase the R above the highest resistor in parallel cluster. If you need to increase the resistance

you need the converter. Don't think about the resistance converter but about voltage converter as the gauge reads the voltage drop.

Simple DC to DC step-up/step-down 5$ converter form ebay will solve your problem.

 

 

 

Share this post


Link to post
Share on other sites

Yes the ECU only transmits to the dash, which gave me hope that it therefore could not know what dash was on the end. However, the ECU might have still sent some flag to say what bike it was and the dash could then refuse to play. So the ECU might say "Hi, F here" and the dash might read that and refuse to use the data because it didn't have an 'X' (CrossTourer) flag. But in the end, fortunately neither end cares. :biggrin:

 

I'll need to think more about the fuel level sender. Yes the dash is just reading a voltage, but it is creating its own voltage dividing network internally so it can detect the changing resistance of the sender which is entirely passive - it's just a rheostat. So I'm not sure the dash would like having a voltage applied to the sense wire. It merely expects a varying resistance to ground. I can add a 70 ohm resister to make it read right at empty, but it will never read full. That'll do temporarily until I work out something better. But it seems to me that I need to create a varying resistance with a greater span. Trying to apply a voltage back to the dash would surely end in tears. Or are you saying different?

 

The X (CrossTourer) sender is 10 - 190 Ohms

The F sender is 13 - 120 Ohms (NOT kOhms that the Honda Service Manual states)

 

Actually, the optimum solution would be to look at the dash circuit board and find the resister it is using internally as it should then be possible to select the right resistance to make it work with the different sender resistances.

Share this post


Link to post
Share on other sites

As I said Ken, you can do it with a DC/DC converter. Just measure the voltage at full and at empty with both, Crosstourer and VFR sensors.

Set the ratio on DC/DC converter and you will be good. Actually no, all uC have typically 0-5V analog inputs without any other circuits.

Analog input circuits are located inside the uC. Sometimes they read 0-12V but this is not common.

 

No, you can't measure the resistance without applying the voltage - is what Ohm law says.

 

And no, as mentioned above there's no resistor inside which you can swap. You would need to change the code in the uC.

 

 

 

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

Appreciate your expertise on this Prez. Trying to get a few things done for the trip in just a few weeks. Shame we're not coming by you this year, but probably will next year and let you know so we could perhaps meet up as we discussed.

 

When I return from this year's trip I'd like to think about this some more and if I could then tap into your superior knowledge, that would be most helpful.

Share this post


Link to post
Share on other sites

No probs - anytime you will be around :beer:

 

Maybe you buy the ECC at some point too :tour:

Share this post


Link to post
Share on other sites

×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy.