This project utilizes the Beaglebone Black platform featuring the ARM Cortex-A8 AM335x 1GHz Sitara Processor.

See the entire project report here.

We will be utilizing the I2C2, GPIO, Clock, Timer5 and Interrupt peripherals embeddedon the device. BBB GPIO Pin 19 and 20 will be used to interface the I2C2 peripheral output with HW-052(PCA9685). This is written in C with embedded assembly in places.

The HW-052 is a I2C addressable, 16-channel, PWM generating breakout for the PCA9685IC. It features external driver power delivery and isolated control voltage. The slave address is adjustable via jumpers for easy I2C stacking of multiple HW-052 boards.

Figure 1: HW-048 Schematic

The PWM outputs from the HW-052 will be used as step functions to drive the AIN2, AIN1,BIN1, and BIN2 pins of a HW-048 (TB6612FNG).

The HW-048 is a Polulu-clone ”stepper motor driver” H-Bridge breakout for the TB6612FNG IC. It features EMF protection, voltage smoothing, and dual PWM-driven step function output.

Figure 2: Truth Table for TB6612 IC

Using both sets of the HW-048 output it is possible to have highly precise operation of a bipolarstepper motor. We will be using a Sainsmart 17-HSR-1006-25 BET nema motor (2014-05-14 manufacturingdate). Part 1 is simply finding success with sending any data on the I2C output. Part 2 will be utilizing the protocol and peripherals to demonstrate controlled rotational movementof the NEMA motor shaft both in clockwise and counterclockwise directions.

Edit: It should be noted that code does not include activation of PWMA and PWMB which are required to be high in order to deliver output. These pins can be tied to VCC +5V to enable output. OE pin must be attached to ground/low to activate PWM functionality.