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 Robotics / NXT / NXT Firmware Hacking / 61
60  |  62
Subject: 
Re: pbLua PCF8574 SOLVED !
Newsgroups: 
lugnet.robotics.nxt, lugnet.robotics.nxt.nxthacking
Date: 
Mon, 21 May 2007 21:50:31 GMT
Viewed: 
118 times
  
Christian Mock wrote:
In lugnet.robotics.nxt, <dickswan@sbcglobal.net> wrote:

This is the excepted behavior. When you want to read from I2C device,
the NXT firmware first sends a write message to load the internal index
"pointer" for the I2C device and then sends a read message that will
read the requested number of bytes. Usually I2C device auto-increment
the internal index pointer whenever a message is r/w multiple bytes.

Hi Dick,
your answer solves my knot :D
It's a NXT specific behaviour and all alternatives NXT-OSes which uses original
Lego-Source-Lowlevel routines have this feature ?

Let me say thanks to Dick as well. I think that the NXT firmware does
what's called a repeat start in the I2C definition...

Here's the part in the I2C spec that is required:

<http://www.i2c-bus.org/RepeatedStartCondition/>

And with pictures:

<http://www.best-microcontroller-projects.com/i2c-tutorial.html>

Hope this helps...

Ralph



Message is in Reply To:
  Re: pbLua PCF8574 SOLVED !
 
(...) Hi Dick, your answer solves my knot :D It's a NXT specific behaviour and all alternatives NXT-OSes which uses original Lego-Source-Lowlevel routines have this feature ? Thanks for your answer Bye Christian (18 years ago, 21-May-07, to lugnet.robotics.nxt, lugnet.robotics.nxt.nxthacking)

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