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Old 06-06-2013, 08:37 PM   #57 (permalink)
jeff88
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Quote:
Originally Posted by Occasionally6 View Post
Slowly. There's no deadline so it happens when I feel like it. It's just playing around with the sketch(es) atm.

The set up hasn't changed; VSS input + analog accelerometer input. I haven't yet set up a speed sensor input. I will do that on the bench before putting it in a car. That is another mini project by itself.

Other than for a vertical displacement (for calculating PE) there is no need for a reset because the VSS is a constant connection to the real world. The reset/reference is only required for dead reckoning which always has some inherent error.
Keep me posted with updates!

How do you bench test the VSS? Are you going to do something similar with the voltage divider and patch ECM cable and whatnot?

So because you are not putting a gyro into the system (yet ) you don't need to worry about the reset then, there's no drift on it right?

Quote:
Originally Posted by Occasionally6 View Post
Clever. That's a nice way to do it, with the 7-segment dp pin wired to an Arduino pin. An extra 7-segment (+ transistor and current limiting resistor for the transistor) just to display the minus sign would also work.
I looked for a triple digit 7-segment display, but couldn't find one in blue (at least not on Amazon). That's why I figured I would do the decimal point thing. I figured I didn't really want to do 2 separate displays, especially just for a negative number which may or may not come on very often anyway.

Quote:
Originally Posted by Occasionally6 View Post
You might start here:

Arduino Playground - MPU-6050

and strip out the temp sensor from the sketch (unless you want that).
I was looking at that one, but I knew it was I2C, so I skipped over it for now. I'll probably go with it, since I can't seem to find any analog ones. It seems to be one of the least expensive options anyway.

Quote:
Originally Posted by Occasionally6 View Post
At the risk of confusing you, Arduino's come in a few different forms, some of which, unlike UNO and Mega, don't have included on the board the means to program them with the sketch. Those need the FTDI breakout (or equivalent) to get the sketch to the Arduino. You could use the FTDI breakout which is needed to program that IMU (which uses the same Atmega328 chip as the Arduino) and an alternative (maybe cheaper) form of Arduino if you have to buy the FTDI breakout anyway.
We'll skip that for now! I think I get what you're saying, but I don't think it's necessary to get into that for what I need.

Quote:
Originally Posted by Occasionally6 View Post
Once you get the sensor input into the Arduino, very little. The units might be different but that's not difficult to deal with. It's just getting the sensor input into the Arduino that is a bit more complicated. That does require a more complex part of the sketch to achieve. It's Arduino so I can't see it being too difficult. I think copying and pasting the code from the playground Arduino.cc link above would do it. (Having written that, I haven't actually done it so...)
I think I will just go with an I2C device then. Once I get it, I can try the copy and paste method and if it doesn't work, then I can tweak it as necessary.

Quote:
Originally Posted by Occasionally6 View Post
For what? I have the two on the power supply that the shield allowed for to damp any fluctuations or noise on that. I think that's probably sensible. I'm going to try some across the (analog) sensor outputs to see if that reduces the noise on them.
To help eliminate the noise. If you try it and it works better, then I figured I should get a couple, especially if it only costs me a few pennies each.

Quote:
Originally Posted by Occasionally6 View Post
Pretty similar as far as I can tell. Aren't they mV per unit of angular acceleration, in degrees per second, the rotational analogy to linear acceleration. The other main gyro spec. is total degrees per second. Measuring slope will be pretty undemanding in terms of that.
So it doesn't matter what measurement rating it is then? Or should I look for the smallest one possible (say +/-250 like the MPU-6050 like you suggested)?
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