It looks like going with a third-party GPS unit will give me more choice and should be easy to integrate.
Looking more closely at the capabilities of the RoboStix...
The ADC is (only) 10bit - Ignoring any improvements possible with dither, on a +/- 10g IMU, the precision will be only about 0.2 m/s^2 (quite poor relative to the accuracy of the accelerometers themselves). Is there a practical way of increasing this precision. If not, i will have to consider using an integrated digital IMU (something i wanted to avoid for cost and because I wantered to implment my own filters on the Robostix), or alternatively an auxiliary ADC (I assume one can buy such a thing).
Additionally, I noticed that the Robostix has 6 dedicated PWM terminals. Can I program the other GPIO pins to perform the same function (whilst carrying the power direct to the servos).
At this point I can wondering if the RoboStix is really giving me anything useful, or if indeed I am going down the right route with hardware.
07 January 2007 19:03:53
Dave Hylands (email@example.com)
General mailing list for gumstix users. (firstname.lastname@example.org)
Re: [Gumstix-users] Which expansion/mother boards - Autonomous Air Vehicle
> It looks like I've completely overlooked the fact that I can only connect 1
> or 2 expansion boards (Basix or Connex respectively) plus a tweener for
> For an Autonomous Air Vehicle:
> I'll need a wireless serial unit for comms (whose interface I am assuming
> will be an RS232).
> I'll need analogue (and probably digital) I/O for sensor inputs and
> filtering, and servo control. I wanted to use a robostix (Hirose 60-pin)
> I'll need GPS. I wanted to use a GPSStix (Hirose 60-pin, but FAQs talk about
> connection via a STUART as on the RoboStix!).
> I wanted MMC for memory expansion. I wanted to use a Basix for its
> MMC.Assuming I use a tweener for connection to my wireless serial link, I
> really think I need a Robostix for general interfacing. Does this mean I'll
> have to forgo the GPSStix or can I use it without connecting the 60 pin
> Hirose and instead connecting it to the RoboStix STUART.
> Can anyone suggest a solution? Thanks in advance
The robostix exposes the STUART and FFUART serial ports as 5v logic
level serial ports.
The GPSstix exposes all 4 serial ports as 3.3v logic level serial, but
uses the STUART to connect to the GPS.
You could connect the robostix directly to the gumstix and use another
Or you could plug ini the gpsstix to the gumstix and connect the
robostix vi i2c.
So the tweener basically acts like a logic-level to RS232 level
You should probably check out these pages:
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