Floating point processor suitable for connected devices

Cortus licenses a range of low power 32-bit processor cores for intelligent connected devices. With growing numbers of controllers in solar energy and industrial control requiring floating point algorithms, many applications require floating point operations executed in hardware to achieve their performance goals.

Complex matrix inversion is a challenging computation in MIMO (multiple-input and multiple-output) wireless systems due to challenges around precision, quantisation and scaling which can be mitigated by using floating point.

“For companies developing intelligent ‘things’ requiring floating point algorithms, our FPS26 core offers outstanding computational performance while efficiently using silicon area”, says Michael Chapman, President & CEO, Cortus. “It is an excellent fit with the industrial internet of things and with power control applications”.

Although historically embedded software has been dominated by fixed-point operations, there are cases where values may have large dynamic ranges and floating point computation is required or advantageous. Examples include matrix inversion in MIMO baseband processing, matrix multiplication and fast Fourier transforms (FFTs).

The FPS26 has a Harvard architecture, sixteen 32-bit registers and a 5-stage pipeline. It offers an IEEE 754 single precision hardware floating point unit, a pipelined parallel multiplier and a hardware divider. It supports the AXI4-Lite bus as well as Cortus APS peripherals. The small size of FPS26 makes it highly suitable for cost sensitive applications.

The CPU starts at around 0.192mm² using a 90nm technology. Using the Linpack benchmark FPS26 delivers 9.7x better floating point performance than the APS25 integer core. Up to eight co-processors can be added to an FPS26 core. The Cortus coprocessor interface allows licensees to add custom coprocessors, for example to accelerate computations in cryptography or signal processing, without knowing details of the internals of the core.

Co-processor instructions can be inserted into C-code appearing as function calls. All cores interface to Cortus’ peripherals including Ethernet 10/100 MAC, USB 2.0 Device and USB 2.0 OTG via the efficient APS bus. They also share the simple vectored interrupt structure which ensures rapid, real time interrupt response, with low software overhead.

The APS tool chain and IDE (for C and C++) is available to licensees free of charge and can be customised and branded for final customer use. Ports of various RTOSs are available such as FreeRTOS, Micrium uC/OSII, Micrium uC/OSIII & TargetOS. To date well over 800m devices have been manufactured containing Cortus processor cores.