Electronica, Munich – The SH7239 MCU has been added to the Renesas Electronics SuperH designed for digital signal processing (DSP) applications, such as servo controls, drives, solar panel inverters and general-purpose motor control.
The SH7239 joins the SH7216 embedded flash MCU and includes many of the peripherals but has a reduced feature set which makes it suitable for the inverter control market.
As the SH7239 MCU is a true MCU with a standard instruction set optimized for C code, Renesas says software engineers no longer need to choose between a DSP for high performance signal processing and an MCU for ease of coding.
Based on the SH-2A core which has a superscalar architecture and two execution units in the pipeline. This allows two instructions to be processed concurrently and code can be executed up to twice as fast as the CPU clock.
In addition, its Harvard-based architecture ensures that no bus conflicts occur between instruction fetch and data access. The SH-2A core also features an optional integrated double precision floating point unit (FPU). These features enable faster DSP functionality on the SuperH MCUs.
The core runs at up to 160MHz on the SH7239 which has with metal oxide nitride oxide silicon (MONOS) based flash memory, allowing execution at full speed with single cycle access to the flash. Renesas says some DSP-style architectures oblige system designers to copy their critical code into RAM in order to achieve faster execution time. This is unnecessary with the SuperH MCUs as MONOS flash is as fast as RAM.
For inverter control, the SH7239 MCU series has a timer unit (MTU2) with six channels of 16-bit timers, supporting up to 16 input capture/output compare functions, and a three-phase PWM capability for electrical motors.
Additional motor control features include a quadrature encoder feedback capability and a special channel that can measure dead times at the power stage.
The MTU2 also incorporates additional safety features with its port output enable (POE) pins that provide a faster and more deterministic response time to ensure safe, fast motor shutdown. Also included is an MTU2S peripheral, a subset of the MTU2. For high performance drives, the timer block can also be clocked with up to 100MHz.
There is a hardware trigger connection between the SH7239 MCU’s inverter timer unit and the three ADC blocks on the devices, which saves CPU loading and time. The 12 channels of ADC all feature 12-bit resolution and 1.0µs conversion time, and there are up to six independent sample and hold circuits in the device to support algorithms such as single-shunt motor drive.
The SH7239 MCU’s registers are arranged in 15 blocks or 'banks'. This ensures that the registers do not need to be popped onto and back from the stack, providing a quicker return from the interrupt subroutine. As a result, the response time to an interrupt request (IRQ) is as fast as a simple branch instruction: 6 cycles.
The SH7239 MCU series features devices with 512k or 256k of flash and 64k or 32kbytes of RAM. It comes in a 120-pin package (16x16mm 0.5mm pitch) and operates at both 5V ± 10% and 3.3V ± 10%.