Low power techniques lead to energy savings

The RISC-351 Zephyr-RR is an energy efficient 32-bit microcontroller core from Dolphin that enables ultra-low power consumption by combining low power techniques with energy saving modes, making it well suited for battery operated applications which spend most of their operating time waiting for a wake-up event.

In order to provide further flexibility in power management than traditional 32-bit competitors, the RISC-351 Zephyr-RR has introduced an advanced state ‘Retention mode’ where essential registers are saved either by using retention registers for the most fundamental ones, or by copying state to/from memory when going to or leaving retention mode for large ones such as the register file. This advanced state retention mode enables the division of power consumption by 1,000 compared to classic power modes where all core and peripheral clocks are gated (stop mode).

Because power modes cannot be implemented without taking into account the ‘wake-up duration’, users have to define the optimal trade-off between the overall power consumption and the lag-time to resume normal operation after entering into a low power mode. This trade-off depends on the number of stored registers, voltage switching etc.

As the impact on embedded software remains a crucial concern for most users, even though the use of the advanced state of retention is a simple software increment with respect to standard retention, a library of dedicated functions is provided with Zephyr-RR in order to make the use of low-power modes straightforward.