FubarStep

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FubarStep

This is a breakout board for FubarinoMini and FubarinoSD chipKIT microcontroller boards. It includes headers for a FBMini or FBSD, a 5V switching power supply, barrel jack for power, 3-pin male .1" headers for every I/O pin, two motor driver chip (able to drive 2 stepper motors - bipolar or unipolar, four dc motors, or other high current loads like LED strings) and power supply routing to enable 5V power to go to 12 of the 3-pin headers for use as RC servo outputs.

FubarStep Board silk screen


Connection Diagram

Usage Notes

Power Supply

5V Input : If you apply 5V to the barrel jack or to the power input screw terminals (right near the barrel jack), you should place the Input Power Select jumper on the "5V In (RAW)" spot. This routes the input power directly to the Fubarino board and directly to the center pin of the lower block of I/O connectors (+5V).

6V-12V Input : If you apply 6V to 12V to the barrel jack or to the power input screw terminals (right near the barrel jack), you should place the Input Power Select jumper on the "6-12V (REG)" spot. This routes the input power through the switching power supply and drops it down to 5V before going to the Fubarino board and the center pin of the lower block of I/O connectors (+5V).

The motor driver chips always receive power directly from the barrel jack/power input screw terminals - their power never goes through the 5V regulator.

The center pin of the top row of I/O connectors is always powered by 3.3V directly from the Fubarino's 3.3V output. There is not a whole lot of power available on this rail - maybe 50mA or 100mA max.

Each SN754410NE motor driver chip has 100uF of bulk capacitance on it's power pin to help smooth out any voltage ripple during rapid current demands.

Power from 5V (center) pin of 3-pin headers

The row of 3-pin headers on the bottom of the board supply 5V from the power input connector or by the 5V switching regulated based on the position of Input Power Select jumper. However, what happens if you don't power the FubarStep from USB or from the power input connector, but instead supply power into the 5V pins on the 3-pin connectors? This might happen, for example, if you have an ESC (Electronic Speed Controller) which normally would power an RC receiver plugged into the 3-pin servo connectors.

Well, in that case, 6V will be supplied into the 5V net of the FubarStep board. This will power all the other things connected to the lower row of 3-pin headers (since the 5V net will have 6V on it), and it will also go up into the Vin pin of the Fubarino (SD or Mini), which will power the Fubarino board just fine. The Vin pin of the Fubarino boards can take 6V no problem, and will feed the 3.3V regulator on the Fubarino Mini and allow the system to run.

I/O Connectors

There are two rows of 3-pin I/O connectors, one along the top of the board (3V3) and one along the bottom (5V). The outer most pin of each 3-pin connector is always ground, and the inner most pin is always connected to an I/O pin on the Fubarino. The center pin is power, and is either 3.3V (for the top row) or 5V (for the bottom row).

Each 3-pin I/O connector connects to a Fubarino pin, and the Connection Diagram above lists which Fubarino pin comes out to which FubarStep pin.

The right-most 12 3-pin I/O connectors on the bottom are spaced a bit further apart from each other (in blocks of 4) to make room for RC servo connectors, which need a bit more space than just 0.1" connector to connector.

Motor Drivers

There are two SN754410NE motor driver chip on the FubarStep board. These are quadruple half-H bridge drivers, which means that there are four output pins on each driver, and that each output pin can be connected to the positive power or to ground, and can source or sink up to 1A.

Bi-polar Stepper motors :

Uni-polar Stepper motors :

BLDC motors :

DC motors :

LED strings :

Design Resources

Schematic: FubarStep v1.3 Schematic graphic

Example Sketches

Projects

Version History