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That may be because they are changing so fast, and there is some ghosting on the display (refresh rate is real slow). I don't have problems reading the speed there, and the position (line of sight, but you have to look down at the speedo) is pretty natural. Somehow, for me, looking down and to the left to my knee just didn't work. Even on my radar detector, centre of the screen, was not natural.
S-2000 Roadster
#1244
Hey, Mark, can you maintain a reasonable update rate without flooding the bus, but simply listen for the AMPS update and then use that event to immediately follow up with a MPH message? Thus, the only time that there's a rush to send out a MPH message is right after an AMPS message has been received.
Admittedly, I've not done any CAN bus programming, so I have no idea whether it is possible for your firmware to listen to the bus and use particular events as a trigger to generate a quick followup message. But it seems like it could work, and at least it wouldn't be as bad as flooding the bus!
That is essentially what we do. The CAN bus protocol is like UDP. It is close to fire-and-forget (more complex at low level, with acknowledgements, but from the application point of view it is "unreliable"). It relies on regular transmissions to get the message across. For example, the AMPS message is sent 10 times a second (or so).
But, I suspect the display is not so simple as to receive a CAN message then display it - I don't think it is directly driven by the messages arriving on the CAN bus. I guess there are several "threads". 1 "thread" receives the message and stores the values in memory. The other "threads" run periodically to take the values and refresh the different parts of the display, and these run at different times. It appears that Amps refreshes very quickly, Range slower, Battery Gauge even slower, and TRIP perhaps only once every 8-to-10 seconds. The problem is that no matter how fast we send our follow-up message, the display refresh "thread" could still happen to pick up the old value. Of course, this is all guess work. There is no manual available, and all we can go by is what we observe.
You can see the TRIP refresh rate yourself. Get up to a significant speed (highway?) and use cruise control. Then, watch how often the TRIP display counts up. Particularly if you have a metric car, you won't see it go 10.1, 10.2, 10.3, etc. More likely you'll see 10.1, (8 seconds), 10.4, (8 seconds), 10.7.
Bottom line, is it would be best for Tesla to do this. I've shown it can be done, and works well. For them, it is a trivial code change, but all the safety, QC and other stuff that must be gone through to make any change makes it work with a lot of downside if they get something wrong. Tesla's emphasis is on the Model S (as it should be), and I'm not holding my breath waiting for this...
There is an app for that also. Try the Escort Radar application for the I phone. It has a "Dashboard" option that gives a pretty accurate speed via the GPS in the I phone. Just mount the phone where it is visible to you. Search apps for "Escort Live"
PV4EV
Member
Before I go breaking something, can anyone advise how to carefully remove the plastic cover / binnacle top covering the two main dials ? I want to be able to get to the signal that drives the speedo...
Alternatively, can the speedo pulse stream be picked up earlier, or somewhere easier to access ??
Thanks in advance.
Alternatively, can the speedo pulse stream be picked up earlier, or somewhere easier to access ??
Thanks in advance.
Does the car stereo have an option to automatically adjust the volume with the speed? If so, you may be able to pick up the signal behind the head unit, if that's easier to get to. Also, since the radio is a 3rd party commercial product, you should be able to find a full installation manual which will help to track down the correct wire.
PV4EV
Member
Mine is a 2.5 with the Alpine / infotainment unit, which doesn’t need a signal from the speedometer cable and uses its GPS instead.
As far as I can work out, Roadsters < 2.0 had a JVC KD-NX5000 that used a crimp connector snapped around the signal lead to/from the speedometer - its on the connection diagrams for the unit.
I'm kinda hoping this same speedometer signal (be it PWM or a pulse stream etc) is still available somewhere behind the dash, and still on the 2.5 loom somewhere.
Can anyone offer advice on this ??
TIA
PV4EV
Member
PV4EV
Member
Thanks
I'm going to poke about behind the Alpine in my car and see if the unused feed is present. It'll be alot easier than getting to the back of speedometer.
Has anyone implemented this using a separate display like a 7-segment or something different than the LCD below the speedo? I have trouble reading the LCD and would like a better, more visible solution. If no one has done it then I might start working on it. PV4EV did you find the speedo feed behind the Alpine head unit?
Thinking about this as a long-term evolution of OVMS. Put a 2.5" touch screen LCD on it and have it on the dashboard. As we're on the can bus, there is a wealth of information that could be displayed. The modem would allow remote control. The displays are not that expensive, but a nice housing is tricky.
Why not use the display of your smart phone, where it already has a nice housing and existing in-car mounting solutions.
Alternatively, Roadster 2.5s could use the display of the double DIN Alpine unit (like Coda is doing).
You can see the speed in the Alpine INA-W900 but it's a different screen. On that speed screen, you can't see your map or control your music so it's of limited use to me at least. They could easily reserve the upper right corner of the music and map display for the speed but they don't.
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