TMS320F28376S: Switch Interrupt Source within ISR

Eyal Saban1

Intellectual 885 points

Part Number: TMS320F28376S

Dear Sir ,

1. We are developing controller based on 28376S

2. The Software has two components , main loop and ISR based on XINT2

3. in some case we need to replace the source of interrupt (instead of XINT2 to be EPWM_INT)

the Switch itself should happen inside the ISR , but issue as i understand that the C28X does context save and restore (when entering and exiting the ISR)

so if i would like to Update IER inside ISR it will be overwrite once exiting ISR (context restore) , is there work around it ?

over 3 years ago

0 Hareesh Janakiraman over 3 years ago

TI__Guru* 95315 points

Eyal Saban1 said:
the Switch itself should happen inside the ISR

Could you simply call the EPWM_INT ISR from inside the XINT2 ISR?

0 Eyal Saban1 over 2 years ago in reply to Hareesh Janakiraman

Intellectual 885 points

Hi Hareesh ,

Thank you for your response , XINT2 and EPWN_INT operates at different frequency both of them call the same ISR,

they are exclusive to each other , the steps of the software is as follow

a. Main + ISR (based on XINT2 at 20Khz)

b. After some time during the execution of ISR i need to replace the source of the interrupt instead of XINT2(20Khz ) to EPWM1(40khz)

both vectors of XINT2 and EPWM1_INT points to the same ISR

0 Hareesh Janakiraman over 2 years ago in reply to Eyal Saban1

TI__Guru* 95315 points

Eyal,

I have requested the help of a software expert to look into your query. Thank you for your patience.

0 Veena Kamath over 2 years ago in reply to Hareesh Janakiraman

TI__Mastermind 32655 points

Hi Eyal,

The IER register would be pushed to the stack. Instaed of writing to IER, have you tried updating the memory location where IER gets saved?

Regards,

Veena

0 Eyal Saban1 over 2 years ago in reply to Veena Kamath

Intellectual 885 points

Hi Veena ,

Thank you for your response , where can i find exactly at which location in the stack the IER is located , also there is risk that if additional

register /varibles will be push to the stuck(due to some code) the location of IER inside the stack will also change , so its location is can be change

am i wrong ?

+1 Veena Kamath over 2 years ago in reply to Eyal Saban1

TI__Mastermind 32655 points

On entering the ISR, hardware automatically stores a set of registers (including IER) to the stack. Software/Compiler also adds additional content to the stack which is also fixed based on how many local variables the function has. So, technically, you should be able to access the location as (SP - fixedOffset)

But, let me check with the hardware experts as well, if there any issues in changing the IER within an ISR

Regards,

Veena.

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TMS320F28376S: Switch Interrupt Source within ISR