Hi Gordon,

Are you still working on the Overo-compatible robot expansion
board? It has been almost a year since you posted this message.
Is the project abandoned?
It would be nice to see such board.

Kind regards,


As we work on the design for an Overo-compatible robot expansion
board, it would be very helpful to know more detail.

As we currently contemplate the board, currently unnamed, it does not
have an additional processor on it (but we could do so).
We suspect that we need all of the PWM, A/D, UART, SPI, GPIO, in
addition to the audio lines and USB-OTG of the Summit board.

The biggest question is about power levels.  We suspect that 1.8V
logic on the PWM is not adequate and are looking at 5V.
A/D would be standard TPS65950 input for ADC2-7 (2.5V)
SPI,UART,I2C make sense at 3.3V...

Question for all PWM users-- would 3.3V be OK?  Or would 5V logic be
better? Or keep them different?

What about V_in range of (approximately) 4V - 17V?

Thanks for any and all feedback.


> Hi,
> I am currently using Gumstix Connex and Robostix in my robots, and I
> am very interested in using the new Overo motherboard, because it
> provides more power, floating point capabilities A/D inputs and PWM
> outputs.
> The summit expansion board can be used in a robot, but it is not very
> well suited to the task. It is like using a breakout board for a
> Gumstix. One has to use additional circuits, on other cards, to
> satisfy basic needs, like driving a servo, or reading an analog
> sensor. The Robostix expansion is there for that, and an equivalent
> for the Overo would be welcomed.
> I understand that expansion boards are being developed and are not yet
> announced, so an expansion board designed for hobby robotics might be
> on Gumstix's roadmap, in which case this mail can be ignored. But if
> it isn't, then I hope that this mail may help Gumstix consider such a
> board.
> What I would like changed compared to the Robostix:
> - the ability to stack it on top of a custom board is currently
> limited by the layout of the Robostix's I/O and power pins. Those pins
> are almost regularly 0.1" spaced, so that an headerless Robostix can
> almost be plugged on a breadboard or prototype board. The "almost" is
> what I would like changed. Between the GPIO banks and the A/D banks,
> there is a space that is not a multiple of 0.1". Similar things can be
> seen on the other side. It would be nice to have a board with 3-ranked
> 0.1" spaced headers on one side (for GPIO, A/D, PWM...), and 2-ranked,
> 0.1" spaced headers on the other side (for Serial, power, ISP...). An
> headerless version of the board (with headers soldered towards the
> bottom of the board) could then easily be stacked on top of a
> breadboard, and custom boards could easily be designed to expand the
> capabilities of such a board (add H-bridges for motors, power
> regulators for 12V to 5V conversion, etc...).
> - the ATmega128 on the Robostix is powerful, but maybe it could be
> replaced by an XMEGA. They provides high speed UART, more A/D lines
> and PWM lines and can run at 32 MHz.
> - the I2C link between the Gumstix and the Robostix is sometimes a
> little too slow. It would be nice if it could run to 1MHz, or maybe
> replaced by an high-speed UART or SPI (it depends and the OMAP
> capabilities on this matter obviously, and I don't know them very
> well).
> I wrote this mail because I think that expressing one's needs is one
> good way to help Gumstix know what we need.
> I am looking forward to seeing Gumstix's future products: thank you
> guys, they are very often awesome.
> Thanks for reading.
> --
> Thierry Genovese
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W. Gordon Kruberg, M.D.
President and C.E.O.,
Gumstix, Inc.

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