topic Re: LPC11UXX External active level interrupt in LPC Microcontrollers

LPC11UXX External active level interrupt

Andy2022 — Wed, 23 Jul 2025 03:04:24 GMT

Dears,

I encountered a issue about active-level interrupt when I use #LPC11U35BFD# mcu. I use the command to control Ex-Interrupt mode and trigger

The similar init code, the edge(rasing or falling) interrupt and level interrupt work well, but the active-level(High or Low) interrupt doesn't work.

I use the command to switch the interrupt mode(Rasing, Falling, High-Level, Low-Level).

NVIC_DisableIRQ(FLEX_INT0_IRQn);

LPC_GPIO_PIN_INT->ISEL |= (1UL << 0); //Level sentisive

LPC_GPIO_PIN_INT->CIENR |= (1UL << 0); //close level interrupt

//Those two configurations only execute one.

LPC_GPIO_PIN_INT->IENF |= (1UL << 0); //enable High Level Interrupt

LPC_GPIO_PIN_INT->IENF &= ~(1UL << 0); //enable Low Level Interrupt

LPC_IOCON->PIO0_2 |= 0x10;

LPC_GPIO_PIN_INT->RISE |= (1UL << 0);

LPC_GPIO_PIN_INT->FALL |= (1UL << 0);

LPC_GPIO_PIN_INT->IST |= (1UL << 0);

NVIC_EnableIRQ(FLEX_INT0_IRQn);

If you have any suggestions, please tell me, thanks.

Re: LPC11UXX External active level interrupt

Alice_Yang — Wed, 23 Jul 2025 09:05:54 GMT

Hello @Andy2022

Thanks for your question.

"level interrupt work well, but the active-level(High or Low) interrupt doesn't work."

->> Sorry so does level interrupt work or not?

And if it doesn't work, I recommend you refer to the pinint demo under LPCopen, firstly clear the status , then configure interrupt.

/* Configure channel interrupt as edge sensitive and falling edge interrupt */
 Chip_PININT_ClearIntStatus(LPC_PININT, PININTCH(GPIO_PININT_INDEX));
 Chip_PININT_SetPinModeEdge(LPC_PININT, PININTCH(GPIO_PININT_INDEX));
Chip_PININT_EnableIntLow(LPC_PININT, PININTCH(GPIO_PININT_INDEX));
Thank you.
 
BR
ALice

Re: LPC11UXX External active level interrupt

Andy2022 — Wed, 23 Jul 2025 15:35:37 GMT

Hi Alice_Yang:

Thanks for your reply.
The Level interrupt works well (High->Low and Low -> High both trigger an interrupt ).

However, I only set High-Level interrupt or Low-Level interrupt, the corresponding operation can't trigger an interrupt.

Thanks very much.

BR,

Andy2022

Re: LPC11UXX External active level interrupt

Alice_Yang — Thu, 24 Jul 2025 10:52:15 GMT

Hello @Andy2022

How about using the three APIs above?

Also, please measure the input signal to confirm that it is high when a high-active interrupt is set.

Alice

Re: LPC11UXX External active level interrupt

Andy2022 — Thu, 24 Jul 2025 12:21:50 GMT

Hi Alice:
Sorry, I haven't used three APIs yet. Because I used Keil.LPC1100_DFP.1.4.1.pack and keil environment(No Keil IDE) to compile code, so I couldn't use three APIs directly. Could you provide those APIs' source code?
And, I observed the Level through Logical analyzer, so I was sure that it is high when a high-active interrupt is set.

Thanks.

BR,
Andy

Re: LPC11UXX External active level interrupt

Alice_Yang — Thu, 31 Jul 2025 02:08:00 GMT

Hello @Andy2022

Please download LPCopen, where you can find the three APIs.

https://www.nxp.com/design/design-center/software/software-library/lpcopen-software-development-platform-lpc11xx:LPCOPEN-SOFTWARE-FOR-LPC11XX

Additionally, there is a GPIO interrupt demo available for your reference.

Thank you.

Alice