LPC MicrocontrollersのトピックRe: USART interrupt handler is invoked only once if Free RTOS API used inside it

USART interrupt handler is invoked only once if Free RTOS API used inside it

sushmasan — Tue, 13 May 2025 18:38:17 GMT

Hello Team,

I am seeing an issue, where the USART interrupt handler is invoking only once when I use the free rtos API inside usart interrupt handler, even though there is a new data arrived.

This is the API called from usart interrupt handler,

BaseType_t xHigherPriorityTaskWoken = pdFALSE; xSemaphoreGiveFromISR(RcvSemaphore(), &xHigherPriorityTaskWoken); portYIELD_FROM_ISR(xHigherPriorityTaskWoken);

When I comment the free RTOS api everything works fine.

Did anyone see similar type of issue?

The reason why I am using freertos api inside the interrupt handler is, I have created free task and in the task handler where I am waiting for a semaphore, which is released from usart interrupt handler when all the data is received, so in the free rtos task handler the data will be processed.

Regards,
San

Re: USART interrupt handler is invoked only once if Free RTOS API used inside it

Harry_Zhang — Thu, 15 May 2025 10:36:30 GMT

Hi @sushmasan

May I ask which chip you are using?

Harry

Re: USART interrupt handler is invoked only once if Free RTOS API used inside it

sushmasan — Thu, 15 May 2025 13:53:04 GMT

Hi @Harry_Zhang ,

I am using LPC55S69.

Finally I found the root cause of the issue.
As part of the processing the received message, in one of the function I am mistakenly using a global array index, the same was used in interrupt handler, due to this there was an array out of bound issue happening.
After using a local variable for index, there is no more issue seen.

Regards,
San