TMS320F28335-Q1: How to disable the FPU module to save power?

Weiliang Xu

Part Number: TMS320F28335-Q1
Other Parts Discussed in Thread: TMS320F28335

Tool/software:

I saw on the TMS320F28335 datasheet that the FPU draws about 15mA current and our application requires minimizing current consumption. Since we do not need floating point computation, I want to turn off the FPU unit to save power. I do not see descriptions in the technical reference about how to turn it off. Is there any way to disable the FPU?

Thanks in advance for advice.

Best regards,

William

3 months ago

0 Sira Rao80 3 months ago

TI__Mastermind 26400 points

You can try changing --float_support to the blank option or softlib in order to avoid using the FPU. This will ensure the built code does not contain any FPU instructions. However, I don't know if this will turn power off to the FPU, or if there's even an option to do that.

0 Weiliang Xu 3 months ago

Prodigy 90 points

Sira,

Thanks for your reply for this question. When I tried to change the float support to softlib, compilation shows errors and complains about the real-time support library that some object files in the rts2800_fpu32.lib specifies "C28FPU32" while the new option requires "C2800", etc. I am using c2000_22.6.0.LTS tool. How can I fix this problem?

Thanks and best regards,

William

0 Benjamin Collier 3 months ago in reply to Weiliang Xu

TI__Mastermind 36526 points

Hi,

I'm currently looking into this, I apologize for the delay.

Best Regards,

Ben Collier

0 Benjamin Collier 3 months ago in reply to Benjamin Collier

TI__Mastermind 36526 points

Hi,

I want to confirm Sira's earlier thought, which is that there is not a way to "turn off" the FPU to save power.

Instead, you will save this 15mA by not using instructions that use the FPU. You can achieve this either with the compiler options mentioned above, or simply writing your code to not use floating point math. If you are having problems with the compiler options, please just audit your code for usage of floating point operations.

Best Regards,

Ben Collier

+1 Weiliang Xu 3 months ago in reply to Benjamin Collier

Prodigy 90 points

Thanks for your clarification.

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28335-Q1: How to disable the FPU module to save power?