Wearable electronics could make use of open-source microprocessors

by Leland Teschler, Executive Editor

Scientists at ETH Zurich and the University of Bologna have open-sourced the design of one of their microprocessor systems. The arithmetic instructions that the microprocessor can perform are also open source: developers made the processor compatible with the open-source instruction set RISC-V developed at the University of California in Berkeley.

The new processor is called PULPino. It is designed for battery-powered devices with extremely low energy consumption (PULP stands for parallel ultra-low power). ETH researchers say the processor could be used for small devices such as smartwatches, for wearable electronics monitoring heart rates and similar parameters, or sensors for the Internet of Things. For demonstration purposes, the group is developing a smartwatch equipped with the PULPino processor and a camera. It can analyze visual information and use it to determine the user’s whereabouts.

PULPino-open-source-microcontroller-like-system — The PULPino open-source microcontroller-like system uses a small 32-bit RISC-V core developed at ETH Zurich. The core supports a base integer instruction set (RV32I), compressed instructions (RV32C) and partially supports a multiplication instruction set extension (RV32M). It implements extensions for hardware loops, post-incrementing load and store instructions, ALU and MAC operations. To allow embedded operating systems such as FreeRTOS to run, a subset of the privileged specification is supported. When the core is idle, the platform can be put into a low power mode, where only a simple event unit is active and wakes up the core in case an event/interrupt arrives. The PULPino platform is available for RTL simulation, FPGA and the first ASIC (called Imperio) was taped out in January 2016.

For now, the main interest in PULPino comes from academics. ETH scientists want to work with other groups to jointly develop academically interesting extensions to PULPino; these would also be open source, thus allowing the number of the hardware’s functional components to steadily grow.

Development costs are reduced considerably with the open-source royalty-free design, said ETH Professor and project leader Luca Benini. “It could result in new research and development partnerships with industry to jointly develop novel chip components on the basis of PULPino.” So PULPino's developers are planning to make their microprocessor more widely known to the open-source hardware community this year.