A 32-Bit MCU Built for Motor Control

Renesas recently introduced the SH7286 microcontroller, which looks like an ideal device to control two motors simultaneously. Of course the MCU needs external drive circuitry, but the inclusion of two multi-function timer/pulse units, MTU2 and MTU2S, will simplify that circuitry by letting designers substitute software for external hardware.  The MTU2 provides six 16-bit timers that control a wide array of internal operations and can work with a 2-phase encoder on a motor. The MTU2S unit includes four 16-bit timers.  Both the timer units can create PWM outputs that drive brushless-DC (BLDC) or AC-induction motors (ACIM) used with pumps, compressors, robots, machine tools, and so on.

Because the SH7286 also includes a USB 2.0 and a CAN port, engineers can use it in designs for industrial equipment that communicates with other equipment. In fact, the SH7286 can perform much like a programmable logic controller, too. To simplify program development, Renesas has begun with motor-control software for:

Sensor-less vector control algorithm for BLDC motors (1-shunt current sensors)

Sensor-less vector control algorithm for BLDC motors (LEM Current Sensors)

BLDC position control algorithm (trapezoidal/ S-profile)

During a talk with Nilesh Rajbharti in Renesas’ System LSI Business Unit, he mentioned one customer who replaced a general-purpose MCU and DSP chip with one SH7286 MCU. The presence of DSP-like capabilities such as a multiply-accumulate, divide, barrel shift, and saturation logic, let the MCU perform DSP operations itself.  (Saturation logic refers to operations that help prevent numeric overflows, not saturation of logic circuits.)

Memory extends up to 1 Mbyte of flash and 32 kbytes of read/write memory. A controller lets applications take advantage of external memory, too.

To get engineers off to a quick start, Renesas offers a “loaner” motor-control board that will drive an AC induction motor or a brushless-DC motor.  The board provides the drive and control circuits and accepts Renesas Starter Kit Board for the SH7286 MCU.  (You could use other RSK boards, too.)  If you don’t want to borrow one of the control boards, Renesas will provide you with details of the board design, component bill of materials, and other information.  Motors can operate between 110 and 220 V AC and up to 20 amps.  During code and circuit development, engineers can use a wide variety of tools from Renesas and other suppliers such as Green Hills, Segger, and Lauterbach.

The Renesas Starter Kit (RSK) for the SH7286 MCU includes a power supply, E10a on-chip debugger, USB cable and CD with software development tools and source files. Interested developers can obtain a coupon code to purchase the RSK at a discount: www.america.renesas.com/ReachSH/a.  When I registered, the Renesas site told me I might qualify for a free RSK.  Have fun.  –Jon Titus