ANNOUNCING: navX MXP Robotics Navigation Sensor

[cjl2625]

I'm trying to get the navX set up for some basic tests.
I plugged it into the roborio, then opened up the roborio example labview project.
I replaced the ip to roboRIO-2067.local and deployed the code (which succeeds), but I can't get any readings out of it..
It just throws a bunch of errors, starting with the serial block.

Am I doing something wrong here?

[Joe Ross]

Originally Posted by cjl2625

I plugged it into the roborio, then opened up the roborio example labview project.

Are you using the Nav6 project? If so, you need to add the serial port parameter to the serial open to use the MXP serial port, as it defaults to the onboard RS232 serial port. I believe there's a better library coming soon.

[slibert]

Originally Posted by Joe Ross

Are you using the Nav6 project? If so, you need to add the serial port parameter to the serial open to use the MXP serial port, as it defaults to the onboard RS232 serial port. I believe there's a better library coming soon.

As an example of what Joe's referring to, please see the attached image.

[slibert]

A good LabView library just got better.

Last year, the original LabView nav6 Serial Port-based libraries were created for the FIRST community by Joe Ross from Team 330 (Beachbots). Now, thanks to the efforts of James Parks from Team 900 (Zebracorns), these libraries have been enhanced to add SPI support and expose some navX MXP and RoboRio-specific features. Following the open-source tradition, these enhancements have generously been made available for all to use. The latest build of this LabView library, which now supports both Serial and SPI interfaces, is now available at https://code.google.com/p/navx.

The SPI Library features lower-latency communication and also lower RoboRio CPU bandwidth utilization. At the default update rate (60Hz), the Serial libraries were measured at 17% CPU utilization, whereas the SPI library was measured at 11% CPU utilization.

Note that the navX MXP also supports I2C communication, and an I2C version of the LabView library is planned; we'll send out an update on this thread when this work is completed.

Thanks to the ChiefDelphi community for continuing to support this open-source project.

[slibert]

navx MXP units have arrived at AndyMark and are now available for sale at the AndyMark online store.

[Dunngeon]

Just bought two, pretty excited about these.

[marshall]

For anyone using LabView with these... we are monitoring this thread along with Scott so we can help if you run into issues. Just let us know. I know James has been happy to contribute and is working on updates to the library in short order.

[cjl2625]

I tried running the SPI labview example tonight.
Seemed to give a nice yaw reading, although the raw magnetometer values were (0, 0, 0), and the MAG_DISTURBANCE light was on.

[marshall]

Originally Posted by cjl2625

I tried running the SPI labview example tonight.
Seemed to give a nice yaw reading, although the raw magnetometer values were (0, 0, 0), and the MAG_DISTURBANCE light was on.

Have you calibrated the magnetometer?

[cjl2625]

Originally Posted by marshall

Have you calibrated the magnetometer?

Oh, nope. I just ran whatever was in the SPI example.
I found the wiki, I'll take at the documentation in there.

[slibert]

Update: in addition to the SPI Labview Library released a few days ago, the Zebracorns have updated navX MXP Labview libraries to include support for the navX MXP's I2C interface. This updated library is now available at the navX MXP online website.

Like the SPI interface, the I2C interface offers lower latency and lower CPU usage than the navX MXP serial libraries.

Thanks again to the Zebracorns for this contribution to the Chief Delphi community.

[pschu5]

I missed the restock on AndyMark last night, I thought they were going to restock on Friday but I guess they must have got them earlier. Any word on when they will restock?

[slibert]

Originally Posted by pschu5

I missed the restock on AndyMark last night, I thought they were going to restock on Friday but I guess they must have got them earlier. Any word on when they will restock?

AndyMark has indicated that all of their units sold out yesterday, which is the same day they became available. More units are being manufactured, and are expected to arrive at AndyMark in early February.

There still are some remaining nav6 units on sale at www.kauailabs.com/store. While I realize this isn't an ideal situation, the navx MXP is backwards compatible with the nav6 serial protocols, so should you choose to use the nav6 now, an eventual upgrade to the navX MXP should be pretty straightforward.

[Thad House]

So for the NavX, would it be a problem to both hook up to the USB port, and hook up to the MXP port?. Where would the processor draw power from, and would this cause any issues with anything else?

[slibert]

Originally Posted by Thad House

So for the NavX, would it be a problem to both hook up to the USB port, and hook up to the MXP port?. Where would the processor draw power from, and would this cause any issues with anything else?

You can definitely do this. In fact, it's very useful to do so, because you can use the navX MXP UI to view what's going on w/the navX MXP at the same time you can access it from the RoboRIO over the Serial Port / SPI or I2C.

The navX MXP has onboard circuitry to allow it to draw power from either the MXP or the USB. If both are connected, the navX MXP will draw power from the MXP port. I won't go into details here, but you can check out the schematics on the navX MXP wiki if you'd like.

The navX MXP has been tested w/both simultaneously connected, and the navX MXP microcontroller can keep up with both w/out impacting performance. In fact, the navX MXP can service all 4 interfaces (I2C/SPI/TTL UART/USB) simultaneously.

There's only one thing to be aware of. The navX MXP has a configurable update rate, which is global to all the interfaces. If that gets changed on one of the interfaces, the other interfaces will also see data at the new update rate. The navX MXP UI requests the maximum update rate (60 Hz) when it starts up. So, if your roborio code has configured a lower update rate on one of the other interfaces, it could change while using the navX MXP UI.

Hope you enjoy this feature, I think it's very useful.