Subject:
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Re: LEGO RCX and I2C
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 21 Mar 2002 09:03:25 GMT
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Original-From:
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Ralf Krause <KRAUSE.RALF@WEBstopspam.DE>
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Viewed:
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699 times
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Hi Steve,
your time stamp is rather wrong ... today it's 2002-03-21 and not 27.
The software seems to be good readable and not like something to bother
with. The author did his work and wrote a lot of comments within the source
so you would be able to learn all about the i2c protocol. (look to the first
lines of the source)
I don't know if the speed is enough for real robots but to light a knight
rider or a 7 segment diplay it's great because it's easy usable.
Ralf
> //===========================================================================
> // File: i2c_master.nqc
> // Description: Single-Master I2C bus communication functions which enables
> // Mindstorm to access a wide range of I2C Slave devices.
> // Remarks: This program requires special hardware on Sensor Ports 1 & 2
> // Compiler: Requires RCX 2.0 firmware, compile with
> // NQC 2.2 or later using -Trcx2 command line option
> // Author: Wim Huiskamp
> // Date: 28-7-01
> //
> // History: V1.0, 28-07-01, First release (Wim Huiskamp)
> // V1.1, 14-12-01, Fixed bug in i2c_ackn for unrolled loop,
> // fixed several comments (Wim Huiskamp)
> //
> //===========================================================================
>
> // General purpose defines
> #define bool int
>
> // I2C serial bus port definitions. Select your preference.
> // The RCX should have my special hardware connected to its sensor ports.
> // Note : The SCL/SDA definitions are used by all I2C subs and functions.
> #define SCL SENSOR_1
> #define SDA SENSOR_2
>
> // I2C globals for subroutines :
> int i2c_data; // Databyte to be transmitted or received
> bool i2c_ackn; // Acknowledge bit to be transmitted or received
>
> // Predefined I2C slave addresses for port expander devices
> #define PCF8574_0 0x40
> #define PCF8574_1 0x42
>
>
> // I2C serial bus output bit banging Macro's
> //
> // Note: Active Ports result in 'low' I2C level on my hardware
> // Passive Ports result in 'high' I2C level
> #define SCL_Lo() SetSensorType(SCL, SENSOR_TYPE_LIGHT)
> #define SCL_Hi() SetSensorType(SCL, SENSOR_TYPE_TOUCH)
> #define SDA_Lo() SetSensorType(SDA, SENSOR_TYPE_LIGHT)
> #define SDA_Hi() SetSensorType(SDA, SENSOR_TYPE_TOUCH)
>
>
> // The following code may be used to replace SCL_Hi. The new macro will
> // wait until SCL actually goes High. This is necessary to deal with slow
> // Slaves that use 'serial clock stretching' to slow down the I2C master.
> // Don't expect to need this here, RCX is slow enough already !
> // Note that we might freeze up the RCX when the bus gets stuck low.
and so on
on 2002-03-27 0:54 Uhr, Steve Baker at sjbaker1@airmail.net wrote:
> Ralf Krause wrote:
>
> > the Elektor - Magazine for Electronics and Computer - comes with a very
> > interesting project. They have a pcb and software in NQC.
> >
> > Have a look to the homepages
> > http://www.elektor-electronics.co.uk/
> > http://www.elektor.de/
> > http://www.elektuur.nl/
> > http://www.elektor.fr/
> >
> > > I2C Interface for Lego RCX 'Brick'
> > >
> > > It has, by now, become well known that the Lego RCX-module is eminently
> > > suitable for experimenting with such things as robotics. But once the
> > > designs
> > > grow beyond simple experimentation it quickly becomes obvious that the
> > > number
> > > of inputs and outputs that this control module provides, are rather
> > > insufficient. That¹s why Elektor Electronics presents the I2C-interface for
> > > this Lego brick. An entirely new world is opened up: in principle, no fewer
> > > than 128 I2C-devices may be connected to the bus!
>
> That's very cool - I've been advocating the use of I2C for Lego robotics for
> a long time.
>
> I'm not sure I'd bother with the interface to the RCX though - I was thinking
> in terms of an I2C computer also.
>
> ----------------------------- Steve Baker -------------------------------
> Mail : <sjbaker1@airmail.net> WorkMail: <sjbaker@link.com>
> URLs : http://www.sjbaker.org
> http://plib.sf.net http://tuxaqfh.sf.net http://tuxkart.sf.net
> http://prettypoly.sf.net http://freeglut.sf.net
> http://toobular.sf.net http://lodestone.sf.net
>
>
--
____________________________________________
Ralf Krause
Bertha-von-Suttner-Gesamtschule Dormagen
Marie-Schlei-Strasse 6
41542 Dormagen
Germany
http://www.bvsdormagen.de
mailto:krause.ralf@web.de
____________________________________________
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