28 Dec 11

R/C modelers can now experiment with new types of servo control with the new Digilent Cerebo MC7 Development Kit. Need motor control? This is a great place to start.

The basic kit includes a demonstration board that features four independent half-bridge circuits rated for 24V up to 5A. These half bridges are connected to the Motor Control PWM Module in the dsPIC microcontroller and can be configured in various ways to control two brushed DC motors, two bi-polar stepper motors, one Brushless DC motor, or one uni-polar stepper motor. The kit also includes eight RC servo motor connectors, and connections for Digilent Pmod peripheral modules. The Cerebot MC7 board is compatible with the free Microchip MPLAB® IDE and the Microchip C30 C compiler for development, programming, and debugging of the dsPIC microcontroller. A USB port is provided for programming and debugging.

Each of the four half bridges can connect to a motor with two N-FET transistors in series such that the half bridge  can either source current or sink current. A 0.01 ohm current sense resistor is connected between the source of each low side FET and ground. The voltage across this resistor is amplified and used as the feedback signal for motor control.

RC Servos generally use a pulse width modulated signal (PWM) to control the servo position. This development kit includes an advanced 8-channel motor-control PWM unit which provides eight output compare units that can be used to generate the required PWM signal for R/C servos.

The dsPIC33 DSC contains 128 KB Flash program memory and 16 KB SRAM, along with various types of serial interfaces including SPI, I2C, UART, and an enhanced CAN controller. The Cerebot MC7 board contains two push buttons and four LEDs for user I/O, and a switching 5V, 4A regulator, which enables it to operate from a single power supply.