gumstix

>connex 400xm-bt, netMMC, GPSstix

I have a connex 400 (without the bluetooth) and netMMC and GPSstix, it
works well.  You still *might* need a tweener or other serial port board
to do u-boot stuff to the motherboard, I still have to unscrew my stack
whenever I do something stupid to the network connection (like firewall
myself out).

(I've also noticed if I add i2c-pxa to /etc/modules, my network connection
doesn't come up, but that's another topic)

You might consider some type of MAX3232 breakout board so you can take
serial connections right from the GPSstix and convert them to proper
RS-232 voltages.

> Hallo,
>
> I have a question about how to configure best a gumstix-computer for my
> requirements.
>
> I need bluetooth, GPS and at least one or two serial ports to have an
> interface to some sensors and engines of my roboter (a blimp which should
> be controlled by an AI-software). First I thought about this
> configuration:
> connex 400xm-bt, tweener, GPSstix, netMMC (to have a possibility to
> connect an other gumstix if more serial ports are needed)
> I found out, that netMMC and tweener will not work together.
>
> Thus I think about two gumstixs with these configurations at the moment:
> connex 400xm-bt, netMMC, GPSstix
> connex 400xm-bt, netMMC, waysmall
> Should these work together? If not, how it is possible to have a serial
> port and a LAN-connection together in one computer?
>
> Thank you for your help.
>
> Tobias-------------------------------------------------------------------------
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-- 
Roger Venable
(734) 272-0795
ICQ: 729414

Hallo,

it is me again, the gumstix-noob. Thank you for your help, Roger, but I have
to ask something simple again.

I still discuss with other members of my project which components are
necessary for us. Because it is a first-time-project in robotics for all of
us, we decided to send you a list of functions and interfaces we need in
hope of a simple answer of some of you with a list of components we have to
buy.

This is the list of things we need:
bluetooth
GPS
RJ-45 (ethernet)
RS-232
I2C (5V)

Because of these, I think we need those components anyway:
connex 400xm-bt (for bluetooth and to connect netMMC)
netMMC (for ethernet)
GPSstix (for GPS)
robostix (for 5V I2C)

I think it is not possible to have these components in one configuration,
but it should be no problem for us, to use more than one connex-board and
connect those via the LAN-Interface. I am not sure, how many interfaces of
RS-232 and I2C are needed. Is it possible to connect more than one device to
an interface of these?

Thank you for your help. I promise future questions will be more challenging
;-)

Tobias

Hi Tobias,

> Because of these, I think we need those components anyway:
> connex 400xm-bt (for bluetooth and to connect netMMC)
> netMMC (for ethernet)
> GPSstix (for GPS)
> robostix (for 5V I2C)
>
> I think it is not possible to have these components in one configuration,
> but it should be no problem for us, to use more than one connex-board and
> connect those via the LAN-Interface. I am not sure, how many interfaces of
> RS-232 and I2C are needed. Is it possible to connect more than one device to
> an interface of these?

Straight RS-232 can only have one device per connector.

I2C supports upto 127 devices, in theory. In practice the limit will
be lower due to bus capacitance.

It should also be possible to connect the robostix up the gpssitx via
i2c. It needs some voltage conversion, but otherwise should work fine.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

> Hi Tobias,
>
> > Because of these, I think we need those components anyway:
> > connex 400xm-bt (for bluetooth and to connect netMMC)
> > netMMC (for ethernet)
> > GPSstix (for GPS)
> > robostix (for 5V I2C)
> >
> > I think it is not possible to have these components in one
configuration,
> > but it should be no problem for us, to use more than one connex-board
and
> > connect those via the LAN-Interface. I am not sure, how many interfaces
of
> > RS-232 and I2C are needed. Is it possible to connect more than one
device to
> > an interface of these?
>
> Straight RS-232 can only have one device per connector.
>
> I2C supports upto 127 devices, in theory. In practice the limit will
> be lower due to bus capacitance.
>
> It should also be possible to connect the robostix up the gpssitx via
> i2c. It needs some voltage conversion, but otherwise should work fine.

I don't know if I understand this correctly:
If I need the robostix for 5V I2C only, in fact I don't need it because of
the 3,3V I2C in the GPSstix. I can connect my 5V I2C devices to the GPSstix
by using a level converter like I would use to connect the robostix with the
GPSstix. Is this correct?

Hi Tobais,

> I don't know if I understand this correctly:
> If I need the robostix for 5V I2C only, in fact I don't need it because of
> the 3,3V I2C in the GPSstix. I can connect my 5V I2C devices to the GPSstix
> by using a level converter like I would use to connect the robostix with the
> GPSstix. Is this correct?

Yep - you got it. It might even be simpler in that many 5v devices can
be connected directly to a 3.3v i2c bus and they'll work just fine.

The secret is that you need to use two pullup resistors for the SDA
and SCL lines on the GPSstix, and these pullups need to pullup to
3.3v.

Many 5v devices will interpret the 3.3v as a logic high, so you can
get away without having to use any voltage conversion.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/