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MN.3
Visitor II
March 15, 2022
Question

I am interested in STM32U5 because of CORDIC as I do have trigonometrically intense applications. Apparently DSP with hardware multiply is superior, and is also provided in the STM32U5. Respectfully, why include CORDIC when DSP is also available?

  • March 15, 2022
  • 3 replies
  • 1350 views

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3 replies

KnarfB
Super User
March 15, 2022

DSP is part of the ARM Cortex core instruction set. These are mainly SIMD (vector) instructions and instructions with saturation often based on combinations of add/sub and mul.

CORDIC is a hardware accelerator for speeding-up trigonometric and hyperbolic functions including logarithms. So they both complement each other.

Side note: my first contact with the CORDIC principle was with my HP-41 scientific calculator in the early 80ies :)

hth

KnarfB

Bassett.David
Associate III
March 15, 2022

The CORDIC operations are faster than a sequence of instructions, but of limited precision. You can also overlap a few instructions while the unit is busy.

S.Ma
Principal
March 16, 2022

In most cases, fixed point uses normal register which enables faster computation within and interrupt. Using more math registers from fpu or else will require potential longer latencies to push/pop them even in lazy mode. And interrupt duration is affecting the max RPM of a motor, for example.