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Subject: 
Re: RCX NXT internals questions
Newsgroups: 
lugnet.robotics
Date: 
Thu, 12 Jan 2006 21:21:03 GMT
Viewed: 
1582 times
  
On Thu, January 12, 2006 3:08 pm, Mark Bellis wrote:
This is what I'd like to figure out:


Mark,

This is a good list, and I think many people are interested in these questions.

We may be able to figure out the answer to some of them...

Sensor and motor expansion:
4. Can the NXT sensor and motor port internal circuits and the sensor and motor
circuits be replicated in a multiplexer

You want a multiplexer that looks like a sensor to an NXT, and looks like an NXT to
several sensors, right?  Logicly, it MUST be possible to create electronics that
look like a sensor, because the sensors do it.  Same for electronics that look like
an NXT.  So, it must be possible to create the electronics.



...with a switchable register to select which
sensor or motor to read or control?

This is THE question.  They've said the NXT uses digital wires.  Do you think the
switching information could be sent digitally?



5. Will there be a proprietary lead to convert 6-wire digital protocol to 2-wire
analogue protocol in order to allow older RCX sensors (active and passive) to be
used with the NXT?

I thought I saw something about this, but I can't find it.



Power supply:

6. Is there a socket for an AC adapter, even if none is included in the set?  If
not, then does the NXT require just 9V DC or 5V DC as well?

Looking at the NXT FAQ page:
http://www.lego.com/eng/service/faqs.asp?section=ConsumerService-FAQ-Products&catid=E8D0CD47-16B8-4B2F-900C-8FC40C163598&faqid=17265#17265

"The NXT Brick uses 6 AA batteries. Alkaline batteries are recommended but
rechargeable batteries can be used but power may be reduced."



7. In the educational version of the RCX NXT, can the battery pack be recharged
or the unit powered without disconnecting the battery pack from the unit?

This is an important question.  Given that there is a "battery pack" as they've said
on the FLL page, there must be a way to recharge it.  Either (A) Charge them in the
robot or (B) unplug them, and charge them.  If the NXT uses option A, should you be
able to run the robot, while the batteries are charging?

If the NXT uses option B, shouldn't you be able to create your own A/C connector
that plugs into the same place as the batteries?



8. Can the regular NXT be upgraded to rechargeable and mains powered status?

Do you think LEGO would make two different versions of the NXT?  (or would the
"educational" version be the same as the other?)




USB Communication:

9. Can a portable battery-powered USB hub be made to service four NXTs without a
lot of software on board (i.e. it would poll the NXTs and deliver simple
messages), assuming it could supply four ports at up to 500mA per port?

I don't really understand why you want to do this, if you have...

Bluetooth communication:

10. If there are three NXTs together, can #1 communicate with #2 over Bluetooth
without #3 listening in?

11. Can #2 and #3 both simultaneously listen to #1 over Bluetooth if desired?

12. Can all three have independent data conversations with each other at once,
or is one NXT limited to communicating with one other NXT, PC or phone at once?

This is more of a Bluetooth question.  As I understand it, BT does not allow you to
"broadcast".  It only allows you to send a message to one other BT device at a time.
But, you can have up to seven devices "connected".



General:

13. Is the internal circuitry highly hybridised (all big custom chips) or are
the sensor and motor port circuits made from discrete components as in the RCX
1.0?

I suspect the development cost for highly hybridised chips would be higher than
descrete components (as in the RCX 1.0)

14. Does opening the unit and removing the circuit board for analysis endanger
the battery clips, as it does in the RCX 1.0?

This would be a good place for a standard discalmer.  "Opening the NXT may damage
the unit and void the warranty".  With that said, if you're careful, you can open a
1.0 without damage.  Right?

Steve



Message is in Reply To:
  Re: RCX NXT internals questions
 
(...) (SNIP) (...) This is what I'd like to figure out: Sensor and motor expansion: 1. What is the sensor port protocol (electronically speaking - internal circuit diagrams with voltage and current levels, timing etc...)? 2. What is the motor port (...) (18 years ago, 12-Jan-06, to lugnet.robotics)

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