Loads of new 16-Bit MCUs with on-chip flash memory from Renesas Technology

Available during October 2008, the new MCUs feature on-chip flash memory, a built-in precision clock oscillator, and enhanced functionality, as well as packages with extra I/O pins. Moreover, within each of these three groups, there are MCUs with or without a CAN1 (controller area network) interface, with various amounts of flash ROM and RAM (32KB/2.5KB, 48KB/4KB, and 64KB/6KB), and with or without on-chip 4KB of data flash2 (data storage flash memory). Versions of the chips are available in two operating temperature ranges: standard (-40 to +85 degrees C) and extended (-40 to +125 degrees C).

The greatly expanded R8C/Tiny product line — now encompassing functionally compatible models with 20-, 32-, 48-, 64-, and 80-pin packages — makes it easier for automotive engineers to find the best, most economical MCU solution for any particular set of application requirements. Also, the broader span of choices allows them to readily accommodate the specification modifications that often arise during the development and fine-tuning of MCU-based body-control systems. They can add functions or increase memory capacity, for example, just by switching to another R8C/Tiny device. This flexibility saves cost and time by eliminating the need for major design changes.

The MCUs in the R8C/38E/36E/34E groups provide improvements in various on-chip peripheral functions. For example, the high-speed on-chip oscillator has improved oscillation precision: ±1%, the industry’s highest ranking. This feature eliminates the external resonator that would otherwise be needed to implement the clock circuit, enabling system cost reductions while also helping to boost reliability.

The data flash built into some of the new R8C/Tiny models eliminates the need for external EEPROM (electrically erasable and programmable read only memory) for data storage. It now has a background-operation (BGO) function that allows the CPU to execute instructions during data flash reading or writing. This boosts the MCU’s processing efficiency and also allows system engineers to write programs without concern for data flash read/write times, simplifying program development. The size of the data flash capacity has been doubled to a total of 4KB (1KB × 4 blocks) compared with previous products, so more data can be stored.

The devices that expand the R8C/Tiny line-up include a data transfer controller (DTC) that enables data transfers to be performed between memory and a register without CPU intervention. This capability shortens transfer-processing time and reduces the load on the CPU, making more computing time available for executing application code. The DTC is based on the highly rated design used in the high-performance MCUs in the 16-bit H8S series and the 32-bit H8SX series.

As before, the new R8C/Tiny chips incorporate a power-on reset (POR) function that places all on-chip circuits in the reset state when the MCU is turned on. However, the revised POR circuit in them has been upgraded for extra flexibility and can now handle a slower ramp-up of the power supply voltage.

Also, like the other R8C/Tiny MCUs, the new devices have a single-pin debugging interface that lets system engineers use the Renesas E8a emulator/on-chip debugger as a development environment — even while all I/O pins are in use — for more efficient program development. The new MCUs, though, have an additional debugging function that allows developers to make RAM references and changes during user program execution, a capability that can improve debugging efficiency. Of course, the E8a emulator retains its capability as a code writer for the MCU’s on-chip flash memory.

Besides the E8a emulator/debugger, Renesas offers a comprehensive set of hardware and software development products for systems that use R8C/Tiny MCUs. Additional support is available from a large international community of third-party suppliers. In the future, Renesas plans to offer support for the E100 full-spec emulator for situations requiring a more powerful debugging tool. The company also will continue to extend the R8C/Tiny line-up for automotive applications with microcontrollers offering improved performance and functions.