Renesas has announced a new generation of R8C family microcontrollers (MCUs) that are based on the latest process technology tailored for high performance 8-bit applications.
Built on a powerful CPU core, the R8C/3x MCUs with on-chip Flash have an extended operating voltage range of 1,8 V to 5,5 V. They incorporate new and enhanced analog functions, including level-only-sensitive power-on reset circuits, high-speed digital-to-analog converters and analog comparators. In addition, their overall performance has been boosted by the addition of a data transfer controller (DTC) and a background operation (BGO) function for Flash memory rewriting.
There are two different product families available: R8C/3xC with advanced features, and the R8C/3xD for applications with reduced peripheral requirements.
The broad memory offering from 4 KB to 128 KB and the package availability from 20 to 80 pins offer product designers increased flexibility and choice. An ultra thin QFN package (0,8 mm) is also available with the 24-pin R8C/3GC and 36-pin R8C/3JC. All of the new MCUs maintain compatibility with existing R8C products, allowing customers to add new features to their current products quickly. Primary applications for the new devices include home appliances, sensor networks, power management equipment and building automation products.
The data Flash in the new devices has a BGO function that allows the CPU to execute instructions while data is being written to or erased from the data Flash. This eases program development since no special consideration needs to be given to the timing of data Flash write and erase operations. Additionally, the capacity of the data Flash memory has been increased to a total of 4 KB (four blocks of 1 KB each), twice that of earlier R8C family chips.
All of the new R8C groups, even the 20-pin devices, incorporate a DTC that performs functions similar to those of a direct memory access controller. The DTC unit manages data transfers from memory to memory, or memory to peripherals, without CPU intervention. While the DTC is handling the data transfers automatically, the CPU can perform other operations, so overall system performance can increase and program code is reduced.
The DTC is tightly coupled to the peripherals so that any hardware interrupt event can trigger the DTC to move data from one location to another in memory automatically for fast response. This capability is useful in many situations. For example, a frequent operation in embedded systems is a transfer of consecutive analog-to-digital (A/D) conversion results to RAM. When the DTC is used to move data from the A/D to RAM, it eliminates interrupt processing through the CPU, reducing this operation’s execution time.
The new R8C devices provide a high-speed on-chip oscillator that provides precise clock signals at 40 MHz, 36,864 MHz or 32 MHz. This high-speed internal clock makes it possible to eliminate the need for an external resonator, reducing overall system costs. The oscillator’s output can be fed directly to drive 16-bit timer units, enabling the implementation of high-speed PWM (pulse width modulation) control.
R8C/3x devices have more on-chip peripherals than previous models in the R8C family. Among the new functions available in all devices are multiple analog comparator circuits, a power-on reset controller that supports slow-rising power supplies, and a high-speed A/D converter unit (2,15 μs) with multiple conversion-result registers. Moreover, the members of the 32-pin R8C/33C group and 52-pin R8C/35C group also include a digital-to-analog converter (DAC).
Additionally, the new devices provide enhanced flexibility with up to five 16-bit timers, two 8-bit timers and RTC. These powerful timers enable encoder function and 3-phase motor control with automatic dead-time generation. Safety functions for home appliances include an independent watchdog timer, ADC disconnect detection and free-of-charge VDE certified self-test MCU software compliant with the European standard IEC60730.