PCB Spec

Two layer PCBOne sided PCB (components only on the PCB top layer)No lead (RoHS)FR-4

Serial Communication

RS 422 interfaceMini-DIN connector

Battery and Power Supply Connection

Need some input in this area

Power Scheme

Reverse polarity protection

DC/DC Converter capable of providing the necessary power to the BBB

Power Management Unit

When the BBB barrel connector is providing power and the batteries are not conected, everything is powered exept for the servos.

When the BBB barrel is connector is not providing power and the batteries or the external power are connected, everything is powered.

When both things are connected, the power management unit (MOSFET switch I'm proposing) shall block the power coming to the P9 pin and only power the servos. The barrel connector, in this case, shall only power the other components.

Load Switch (Logic behind this scheme)

Battery Discharge and Voltage Sensing Scheme

Voltage sensing circuit capable of doing a linear transformation from unregulated high voltage to a lower readable voltage (3.3V)

Noise isolationFast A/D with I2C digital interface for fast data acquisition.

EEPROM

Cape ID and Cape pins reconfigurationI2C digital interface for fast data acquisition.

PWM Driver Scheme

Dedicated embedded system to facilitate communication between the BBB and the PWM Driver.

i2c-controlled PWM driver with a built in clock. That means that you do not need to continuously send it signal tying up your microcontroller.

I2C digital interface for fast communication with the module.Adjustable frequency PWM up to about 1.6 KHz12-bit resolution for each output - for servos, that means about 4us resolution at 60Hz update rate

Configurable push-pull or open-drain outputOutput enable pin to quickly disable all the outputs

SPS Spec SheetTuesday, May 27, 2014

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