Renesas Technology America has introduced two 32-bit microcontrollers with flash memory configurations and peripheral sets suited for lane-departure warning, adaptive cruise control, blind-spot monitoring, and other driver-assist systems that implement preventative safety features to help drivers avoid potential accidents. Renesas noted that preventative safety system are migrating down from premium automobiles to become persuasive selling points for buyers of mainstream vehicles.
Based on the superscalar, RISC-type SH-4A central processor and fabricated on 90-nm process technology, the 240 MHz SH74504 and SH74513 include 2 MB and 1.5 MB of on-chip flash memory respectively, plus 512 kB of SRAM, and 64 kB of cache. The MCUs come in a 17x17 mm, 292-pin BGA package and operate over a -40°C to +125°C temperature range. Both provide a 5-channel CAN function to accommodate a larger number of sensor and actuator electronic control units. The SH74504 also offers a 2-channel FlexRay function.
Paul Kanan, marketing manager in Renesas’ automotive business unit, said that at 240 MHz the new MCUs achieve 432 MIPS (million instructions per second) and 1.68 GFLOPS (billion floating point operations per second) while consuming 1.5 watts of power. He added that the high-speed calculating capabilities of the built-in hardware floating point unit (FPU) accelerate vector and sine/cosine arithmetic computations, thus, the devices can process data quickly to deliver rapid situation updates in fast-changing, real-world driving situations.
Kanan said on-chip flash memory is sufficient for storing the complex code typical of image-recognition and threat-analysis programs, the MCUs’ 512kB on-chip SRAM allows the MCUs to handle large amounts of data, and their 64 kB cache (32 kB for instructions and 32 kBb for data) optimizes CPU throughput.
For on-board camera control, a 3-channel direct RAM input interface function supports a direct parallel connection at up to 40 Mb/s between a CMOS camera with up to WVGA resolution and the MCU’s on-chip SRAM. A 1-channel I2C function handles camera settings. Kanan said the 512 kB SRAM is sufficient for storing the data for an entire photo, so designs can be smaller and cost less.
A parallel D/A controller circuit controls the D/A converter required by millimeter wave applications. A parallel selector circuit provides channel control of a high-speed A/D converter and a dual-ring interconnect circuit for applications that call for capturing data from a high-speed external A/D. A timer output unification timer is available for controlling the brushless DC motor that sweeps the radar antenna, and a 65-channel advanced timer unit III (ATU-III) multifunction timer provides timer control capability.
For multi-CPU in-vehicle systems, both MCUs offer a dual-ring interconnect and a direct RAM output interface, a parallel selector (PSEL) bus controller can set the optimal data bus width when an external bus is used. An 8-channel serial communication interface with FIFO can be used for message exchanges, and an on-chip direct memory access controller supports data transfers to external bus areas.
“The SH74504 and SH74513 make it possible to build reliable preventative-safety designs that deliver important application benefits, while also meeting the tight cost targets necessary for affordable pricing,” said Kana. “In the years ahead, such technologies will play an important role in creating an anxiety-free driving experience by enhancing safety and convenience.”