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Renesas RL78 16-bit Microcontroller
The RL78 was the first new mcu core to emerge from the new Renesas Electronics company from the merger of NEC Electronics and Renesas Technology and incorporated the features of the NEC K0 and Renesas Technology R8C microcontrollers.
The RL78 was developed to address extremely low power but highly integrated microcontroller applications, to this end the core offered a novel low power mode of operation called “snooze mode” where the ADC or serial interface can be programmed to meet specific conditions to wake the device from the extreme low power STOP mode of 0.52uA.
The RL78 family became available with a range of devices from a 20pin 16KB flash memory to 128pin 512KB of flash memory. This RL78/G13 microcontroller family included a +/- 1% on-chip oscillator, watch dog timer, RTC, power-on reset, low voltage detection, 26 channels of 10bit ADC, 16x16 Multiplier, 32/32 Divider, I2C, CSI/SPI, UART, LIN, multi-function timer array and also built-in IEC 60730 safety support in hardware. This combination of elements enables the system designer to achieve high performance (41DMIPS) systems operating at very low power levels and at low cost due to the high level of integration in the microcontroller.
A smaller version of the RL78/G13 was introduced in 2012, the RL78/G12. Introduced with 20, 24, and 30-pin packages with 2 KB to 16 KB small size flash memory although providing the G13 functionality with integrated +/- 1% 24 MHz oscillator, reset circuit, a low voltage detection circuit, watchdog timer, data flash with background operation, and including functional safety, on-chip with A/D converter testing function.
This small device is designated for use as a sub-microcontroller suitable for use as in small home appliances and general consumer electronic devices.
In 2012 an addition to the RL78 family was introduced called the G14. This device offers higher levels of integration with the inclusion of additional multiply and divide and multiply-accumulate instructions capable of faster processing than the RL78/G13, 2 Channel 8-bit D/A, 2 Channel comparator, and timer array making it suitable for motor control applications.
Multi-function Timer Array Unit (TAU):
Timer array with encoder function
- Timer array unit (16-bit, 8 ch)
Interval timer (12 bit, 1 ch)
Watchdog timer (17-bit, 1 ch)
Full real time calendar function
Motor control timer (16-bit, 8 ch)
Phase timer (16-bit, 2 ch)
I/O timer (16-bit, 1 ch)
An application specific version (ASSP) of the RL78 core was introduced in 2012 for controlling lighting systems, this device was named the RL78/I1A. Specific features of the device such as special PWM timers enable fine dimming, lighting sequence and colour temperature control with power factor correction of the power supply. In addition integrated communication functions for DALI, DMX512 and multiple sensor & user interface controls are provided. Applications for the RL78/I1A include: building automation, LED drivers, lighting controls, fluorescent ballasts, emergency lighting, HID ballasts, digital power supplies, low-cost inverter controls.
Microcontroller series with LCD Drive
Entering mass production at the beginning of 2013, the RL78/L12 includes integrated LCD drive capability for 35 segments x 8 or 39 segments x 4. Three alternative LCD drive methods mat be enabled: split capacitor, capacitive charge pump or external split resistor. With the split capacitor method a low power LCD drive of 0.6uA at 3V can be achieved. Selectable functions (Seg or I/O) for every segment pin, and drive for both glass and panel.
Software and Development tools
The RL78 family is supported with a range of Hardware and software development tools including the GNU Compiler Collection and IAR Systems compilers with an integrated design environment called Eclipse Embedded Studio or e2studio, CMX, Micrium, Segger, and FreeRTOS real-time operating systems can be supported.
The RL78 microcontroller is suited to White Goods (washers, dryers, dishwashers, refrigerators), Small Appliances (power tools, vacuum cleaners, coffee machines), Consumer Electronics, Medical (tooth brushes, blood glucose meters, ECG sensors), to Factory Automation (sensors, gauges, actuators) and Smart Energy (metering, energy control, lighting).