F28335 Can High Priority Interrupts Interrupt Low Priority Interrupts

Edward Sanders

Greetings,

I have a need, in a small section of code, to block all interrupts except the PWM interrupt. Is it possible to have a higher priority interrupt interrupt a lower priority interrupt? If the lower priority interrupt sneaks in a cycle before the higher priority interrupt, how much latency will there be before the PWM interrupt is taken?

Thank you,

over 10 years ago

0 ToddMullanix over 10 years ago

TI__Guru* 96960 points

Hi Edward,

What version of TI-RTOS of TI-RTOS (or SYS/BIOS) are you using?

Todd

0 Edward Sanders over 10 years ago in reply to ToddMullanix

Intellectual 430 points

Hi Todd,

How can I tell which version I am using? Currently, I am running on the C2000 Development board. I'm not sure if it will make a difference, but I will soon be moving to an eZDSP.

Thanks,

0 ToddMullanix over 10 years ago in reply to Edward Sanders

TI__Guru* 96960 points

The version is in the release note and also in the directory name. For example: C:\ti\tirtos_c2000_2_12_01_33 (if you are using TI-RTOS) or C:\ti\bios_6_45_00_20 (if you are just using SYS/BIOS).

Todd

0 Edward Sanders over 10 years ago in reply to ToddMullanix

Intellectual 430 points

Todd,

Under the ti folder, all I see of that nature is bios_5_42_01_09. There are no tirtos folders.

Ed

0 ToddMullanix over 10 years ago in reply to Edward Sanders

TI__Guru* 96960 points

Are you using the DSP/BIOS kernel in your application?

Todd

0 Edward Sanders over 10 years ago in reply to ToddMullanix

Intellectual 430 points

Sorry to sound like a broken record, but how do I determine that?

0 ToddMullanix over 10 years ago in reply to Edward Sanders

TI__Guru* 96960 points

Do you have a .tcf file in your project? Do you make kernel calls like TSK_sleep, SEM_pend, etc. in your application?

I'm asking because DSP/BIOS manages the interrupts for you. If you are not using DSP/BIOS, I'm going to move your thread to the C2000 forum. They will be able to answer your question better.

Todd

0 Edward Sanders over 10 years ago in reply to ToddMullanix

Intellectual 430 points

I am not making any calls like that. I am calling some routines which are part of the TI environment when I include "DSP28x_Project.h and DSP2833x_Device.h. I don't know if any of those routines will make any of the kernel calls you mentioned.

Ed

0 ToddMullanix over 10 years ago in reply to Edward Sanders

TI__Guru* 96960 points

I've moved your thread to the device forum since you are not using TI-RTOS.

Todd

0 Mark Labbato over 10 years ago in reply to Edward Sanders

Guru 30330 points

Ed,

Please Search for interrupt nesting in the C2000 E2E area. There are various posts specifically on this subject.

The short answer is that the C2000 is capable of doing nesting interrupts, but you must manage it manually. By default interrupts are disabled in any ISR so they cannot be interrupted. You can re-enable interrupts inside of your ISR to do whatever nesting is necessary.

For interrupt latency, the System Control User Guide explains the Interrupts for the device.

Thanks,
Mark

0 Edward Sanders over 10 years ago in reply to Mark Labbato

Intellectual 430 points

Mark,

This answers my question. Since I cannot control the time when interrupts would be re-enabled, I need to continue disabling all interrupts during that time, which I am doing now. Doesn't feel good, but it works.

Thanks for your help.

Ed

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F28335 Can High Priority Interrupts Interrupt Low Priority Interrupts