Sunday, March 29, 2009

Overo Connections - reaching the outside world....

While the Overo Earth computer, in it's present form, has a great potential for all sorts of applications it has a "minor" drawback... Very little in the way of outside communications! While the computer has two 70-pin connectors with all sorts of input and output capabilities most, with the exception of companies with the skilled workforce, will have problems connecting to the computer!

To aleviate this problem Gumstix has an expansion board the Overo Earth plugs into that brings all sorts of connectivity to the miniscule computer board - Enter the Summit Expansion Board.

As you can see from the image to the right there are several connecitons available on the expansion board that allow you to access different aspects of the Overo Earth computer:


  1. USB OTG mini-AB

  2. USB host mini-A (experimental)

  3. DVI-D (HDMI) video out

  4. Audio In / Audio Out (stereo)

  5. USB Serial Console

  6. 40-Pin connector location on board
    (Signals available on 0.100-inch through-holes at 1.8V logic levels)

  • Two (2) two-wire serial ports

  • One 1-wire port

  • 6-ea. PWM output lines

  • I2C port

  • SPI Bus

  • 6 ea. A/D lines (at 1.8-V logic)

  • processor control signal lines.

Power: 4V to 5.5V input

Connectors: 2-ea. 70-pin AVX 5602-24 connectors
(interface to Overo Earth board)

Size: 80mm x 39mm

Mounting: Four (4) x #2 mounting holes

Points of Interest:

  1. As delivered the Overo Earth/Summit USB-OTG port is configured as a host port - you will need either a mini-A USB to mini-B cable (available from Gumstix for a reasonable price) or you will need to perform a modification (add a jumper) to the USB-OTG port. If you have really good soldering skills (the connector pins are really small!) you can put a solder bridge between pin-4 and pin-5 on the circuit board side of the USB-OTG connector to fool the computer into detecting a mini-A connector when you have a mini-B connector plugged into the USB-OTG port (this is exactly what the mini-A connector does). Personally I think it is better to just spend the small amount of money and order the correct cable - and if you plan to use the USB Host connection you will need a mini-A to mini-B cable anyway as the USB Host connector is designed for mini-A USB connector ONLY.

  2. While the video output port is labeled "HDMI" and the Overo Earth is capable of HD-720P the factory configuration is currently 1024 X 768. If you want a different resolution you will need to setup a development environment and recompile the kernel to make the change to a different display resolution. If you don't have a monitor which supports DVI-D (or HDTV) then you will need to get a DVI-D to RGB converter to see the display.

  3. The USB Console port is just that - the console connection to access the Overo Earth operating system during bootup or as a local terminal. In the Linux/Unix world there is a "console" that can be seperate from the normal display, and usually is. This allows debugging and initial configuration or configuration changes without the need for the system to be booted completely up where the connected keyboard, mouse and or display may not be active yet. Normally you don't need to have a "console" connected but it sure can come in handy if there is no other way to communicate with the system (provided the operating system is running and recognizes the console). During the bootup process messages are printed to the console so this port is very handy during bootup troubleshooting.

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