RS485 NXT-G Block

[mightor]

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- Xander

[haydenstudios]

Thanks Xander. Are you saying that it will be posted on your blog when the next version comes out? Or are you just encouraging me to check your blog more often to learn more about LEGO MINDSTORMS? It seems like the methods of publicity would ultimately be up to Andy(not the gloomy one, but the Andy who started this thread).

[mightor]

Are you saying that it will be posted on your blog when the next version comes out? Or are you just encouraging me to check your blog more often to learn more about LEGO MINDSTORMS?

Regardless of where Andy will end up posting or publishing his code, I will blog about it Andy and I are good friends and he does not have a blog of his own yet. That's why it is not unlikely that it will be published on my blog. However, that said, it's also possible he's going to start his own, although I kind of doubt he has the time for it, he's really rather busy with a number of top secret projects for LEGO

It seems like the methods of publicity would ultimately be up to Andy(not the gloomy one, but the Andy who started this thread).

Yes, it would be, but that would not stop me from blogging about it We've both been doing testing for Dexter Industries NXTBee sensors, which is one of the main reasons Andy started with the development of the RS485 block.

- Xander

[milluzaj]

Hey guys. Sorry for the long delay. I hope to pump a new one out by tomorrow.

It has been a very long 2 weeks. I have a few projects that are due today, so after they are done, I will work on it tonight.

[milluzaj]

This will have to happen tomorrow or Monday. I am at Brickworld Indy this weekend and it is much busier than I expected (which is a good thing).We shall see if I get some down time tomorrow or not.

I have the one reported bug to still fix. I think I have solution in place, but I need to test it a bit more. I think it is a timing issue in the wait loop. More details in the release notes.

[nxtreme]

I noticed something interesting on the Dexter Industries website a couple days ago. I wasn't sure if it was just a mistake, or if there was something I didn't know about. This page for the RS485 block states that "The block can communicate at speeds of up to 9.6 kbps..." which is a bit misleading in light of my comment on Xander Soldaat's blog. The phrase on the DI website leads me to believe that it is DI's mistake, mostly because I2C functions at 9.6KBps as well. It also says up to 9.6KBps, when I thought it worked at a fixed speed. Does anyone care to enlighten me?

[milluzaj]

nxtreme, yes their website is misleading. The block runs at 1 Mb/s. Also the block specifically for the Xbee will be 200 Kb/s (I dont remember the exact numbers off the top of my head, but I know what it would be in data bytes, lol). This is locked by the firmware. The standard firmware locks it at 1 Mb/s. The next version of the block allows you to select if you are running on a standard or enhanced firmware. If you are enhanced, you can change the baud rate. (This is also supported in the xbee block.) The block I am making for the xbee will be coming soon behind the RS-485 one.

I am sorry for the delay but I have a ton of (lego) projects on my plate now, plus school and work.

[mightor]

The XBee has two interfaces:

• The one the NXT talks to (UART)
• The Xbee-to-Xbee one (we'll call it XNet for the sake of simplicity)

The UART can talk at standard baud rates ranging from about 1200 baud right up to 115200. However, it can also be configured for non-standard speeds up to 250kbs. The XNet interface is one we can't control. It always communicates at 250kbs.

The default speed for the XBee's UART is 9600kpbs. This is the factory default. In fact, you'll find that most standard industry devices will fall back to this default speed. If you're using the official baud rate speeds, you could crank this UART up to 230.4kbs. If you don't care about that stuff, you could specify your own and use 250kbs, for example. Using these higher speeds in a noisy environment may mean more lost packets because the XBee won't have time to retransmit. If this is something you take care of in your driver then that's OK. I tend to stick with 115.2kbps but have experimented quite nicely with 230.4kbs.

I hope this explains the numbers a bit.

- Xander

[jdc2106]

Hey folks, just FYI, I just updated the Dexter Industries website to properly reflect it. Hopefully it's not misleading any more!

RS485 Sensors: http://dexterindustries.com/rs485.html

[nxtreme]

Thanks for all the replies! I'm eagerly waiting for the next version of the block, but no rush . I've played with low power 315MHz radios before, so I know what high speed communications will do to a radio link. I really like the concept of XBees, but they are a bit too expensive for me right now. That's why I was interested in the lower speed comms, so that I could try implementing some wireless networks using cheaper wireless radios.