GIOA level sensitive interrupt

Stefan Steinmann

Other Parts Discussed in Thread: TMS570LS3137

Hi,

we are using a TMS570LS3137.

We have configured GIOA pin 4 to generate interrupts on the falling edge. Everything is working fine so far.

Our interrupt pin is controlled by an external device (low active) and we would like to stay in the interrupt and process some data as long as the line remains low.

We are clearing the interrupt flag by reading GIOOFF1 register upon entering the interrupt handler.

As our external device is not releasing the interrupt line as long as some conditions are fulfilled, we would need to configure the interrupt for low level instead of a falling edge.

Is there any possibility to configure the GIOA module to generate interrupts on low level (level sensitive instead of edge sensitive)?

In the TRM I've found the information that the interrupts are level sensitive whenever the device is in low power mode. It is stated that the low power mode is left whenever a corresponding level on the input pin is detected.

Unfortunately there are not many more informations regarding the low power mode.

Additionally to pin 4 (input) we are using other pins on this module as outputs. Are they switched off in low power mode, or do they maintain their state? Are they still switchable in low power mode?

Is the low power mode even entered while pin 4 would be already low?

Regards,

Stefan

over 11 years ago

0 Chuck Davenport over 11 years ago

TI__Guru 59540 points

Hello Stefan,

I have forwarded your questions to one of out LS3137 device experts. They should reply to you soon.

0 Michael Sch, over 11 years ago in reply to Chuck Davenport

Intellectual 800 points

Hi Chuck,

do you have any news regarding this topic?

Kind regards,
Michael

0 Jean-Marc Mifsud over 11 years ago in reply to Michael Sch,

TI__Mastermind 22375 points

Stefan,

I'm not sure I understand what you are looking for.

Do you want to re-enter your gio isr as long as the gio is low? This is the reason why you want level instead of edge?

Please can you confirm?

0 Stefan Steinmann over 11 years ago in reply to Jean-Marc Mifsud

Intellectual 410 points

Hello,

yes, we would like to enter the interrupt as long as the gio is low.

0 Jean-Marc Mifsud over 11 years ago in reply to Stefan Steinmann

TI__Mastermind 22375 points

Stefan,

In this case, in your ISR, don't clear the flag.
As soon as you will exit the ISR, the pending request will kick your code back to the ISR.
In order to exit this "loop" you can switch your GIO from falling edge interrupt to rising edge and change the level on which GIO interacts with VIM . (GIO are able to generate 2 requests, low and high on 2 separate VIM channel). When eventually this input is high, you will be notified by executing a different ISR than the one for falling edge. In this ISR you can clear both request (falling edge and rising edge) and reconfigure the GIO for falling edge detect.

Please let me know if this is clear.

0 Stefan Steinmann over 11 years ago in reply to Jean-Marc Mifsud

Intellectual 410 points

Thanks for your suggestion.

I fully understand it, but it wouldn't solve our problem. It could happen that after the rising edge a new interrupt is generated by our external device and is generating a falling edge even slightly before we are clearing both flags. There is some race condition between the CPU and the external device which is not solvable without having a level triggered interrupt. And as far as I understood this is not possible with the GIOs.

0 Jean-Marc Mifsud over 10 years ago in reply to Stefan Steinmann

TI__Mastermind 22375 points

Stefan,

This is correct, GIOs are edge sensitive and not level.

Can you explain what kind of processing you are doing in the ISR when the gio is low?

0 Stefan Steinmann over 10 years ago in reply to Jean-Marc Mifsud

Intellectual 410 points

Thanks for your feedback. We will search for another method instead of using the GIO interrupt.

Arm-based microcontrollers

Arm-based microcontrollers forum

GIOA level sensitive interrupt