How can I set fpu_interrupt_mode?

[zester926]

Hi Devzone!

I'm planning to integrate fpu_fft with ble_app_uart, and did it.

I wanna use IRQ of fpu_fft but I can't find where I should define fpu_interrupt_mode.

Where can I find it?

Best regards,

Baek

[bjorn-spockeli]

HI Baek, 

in the nRF5_SDK_16.0.0_684aa2c\examples\peripheral\fpu_fft\pca10040\s132_irq example we're defining the FPU_INTERRUPT_MODE in the Preprocessor Definitions. 

In SES, right-click the project, click Options, select the Common configuration in the drop-down menu in the upper right corner, then navigate to Code > Preprocessor > Preprocessor Definitions and add FPU_INTERRUPT_MODE there. 

Best regards

Bjørn

[zester926]

Hi Bjørn!

 

Thank you a lot!

What is the difference between fpu_interrupt_mode and just fft?

Is there any good points when using interrupt_mode from a performance perspective?

Best regards,

Baek

[bjorn-spockeli]

With the interrupt enabled the floating-point unit can generate an interrupt when one of several exceptions occur. The exceptions are underflow, overflow, divide by zero, invalid operation, input denormal, and inexact exception.

So in short,in interrupt mode you can be notified about exceptions that occur during the floating point operations. The alternative is to poll the FPSCR register- 

Performance wise in terms of the actual FPU operations it should be the same if you use the FPU interrupt or not.

Best regards

Bjørn

[zester926]

Hi

Thank you so much!! now I can understand it.

Always thanks a lot for detailed answers from Devzone.