2015 Beta Testing - The Components are Here.

[controls weenie]

Originally Posted by SteveGarward

I certainly hope they do - for everyone. That clarification makes the current preliminary rules much more broad that I had anticipated or understood them to be.

I have been reading many of these post and I have not understood the benefit of the mxp pcb. All I can see is that it is an exercise in relocating the connector from deep inside the 2x17 male connector. I have several expansion ideas but my thoughts are to connect directly to the 2x17 male connector. I am not seeing the benefit of the expansion board. Moreover, there are no active or passive issues. What am I missing?

[RufflesRidge]

Originally Posted by controls weenie

What am I missing?

That wiring the signal and ground of a 3 pin connector to the signal and ground mixed into the 34 pin connector is a pain. A huge pain if you want to use more than the number of ground pins available.

[SteveGarward]

Originally Posted by controls weenie

I have been reading many of these post and I have not understood the benefit of the mxp pcb. All I can see is that it is an exercise in relocating the connector from deep inside the 2x17 male connector.

Yes and no. It allows you to have easy access to the pins in the MXP, and lay them out in a manner that is easy to use - such as providing ground pins and in a 3-pin arrangement so you can plug in a regular PWM cable. To relocate the connector we just need a cable. You then still have the issue of what you connect to it and how.

Originally Posted by controls weenie

I have several expansion ideas but my thoughts are to connect directly to the 2x17 male connector.

You could use a connector with a cable and solder the wires directly to things, for sure. It's just often more inconvenient to do so, depending on what exactly you're trying to do.

Originally Posted by controls weenie

I am not seeing the benefit of the expansion board. Moreover, there are no active or passive issues.

The benefit is 'ease of handling'. Given the current preliminary rules/rulings/statements (especially today's response on the forums), I'm not sure where just plugging something straight in (say, an encoder) through wire on a cable/connector would sit on the active/passive fence. But, they are working on it.

[GeeTwo]

Originally Posted by Ether

Using a simple model of the battery as a fixed internal resistance of 0.011 ohms in series with a constant 12.7v voltage source, it's straightforward to compare the energy wasted across the internal resistance for the same ampere-hours at different currents.

But it's even worse than that. A close look at the battery discharge curves suggests that the internal resistance is not constant, but rather increases substantially with current.

This is not at all surprising. Most resistors increase in resistance as the temperature goes up, like when they have a lot of current running through them. In addition to the reduction in the battery's reduced capability as reflected on the discharge curves, you are also losing more energy to heat in the wiring and the motors at high draw.

[jhersh]

Originally Posted by Joe Ross

Sample rate is 40hz, resolution is 1/8 amp. Latency seems to be less then then the sample rate, we compared it to an analog current sensor we used last year and didn't see any unexpected latency. I haven't seen any specs on max current, but it measured 60+ amps per channel on our drivetrain.


I've attached data we collected from the PDP during a match at the SCRRF Fall Classic. Note that each channel has a small steady state error, which will be calibrated out in a later firmware update.

Hi Joe,

Do you think you have the DS log for this match that you could attach or send to me?

Thanks,
-Joe