STM8S105C4, are nested interrupts recommended for TIM4 and UART2?

[Kmax18]

Hello, I am new to ITC. I use a the TIM4 interrupt as a 10ms time base, using a callback function for the SPL interrupt handler INTERRUPT_HANDLER(TIM4_UPD_OVF_IRQHandler, 23).

The callback transmits a UART2 packet to an external device and then waits for a UART2 response packet. The response is received using the UART2_IT_RXNE_OR interrupt and the callback for the SPL interrupt handler INTERRUPT_HANDLER(UART2_RX_IRQHandler, 21).

The default interrupt priorities are used for all interrupts: Level 3 (lowest).

The dev. environment is STVD and STM8 Cosmic compiler.

See the below pseudo code.

Problem:

The while() loop in the TIM4 interrupt routine blocks the UART2_RX interrupt.

Question:

Is it good practice to wait for the UART2 IRQ in the TIM4 interrupt routine? Is a nested interrupt setup a good solution, and how to implement this on the STM8S MCU? Section 6.5.2 in the reference manual is brief. Thank you!

Callback_for_TIM4_UPD_OVF_IRQHandler()
{
    /* Disable the UART2_RX interrupt */
    UART2->CR2 &= ~UART2_CR2_REN; // disable RX 
    UART2->CR2 |=  UART2_CR2_TEN; // enable TX 
    UART2_ITConfig(UART2_IT_RXNE_OR, DISABLE);
 
    Send_UART2_packet();
 
    /* Enable the UART2_RX interrupt */
    UART2->CR2 &= ~UART2_CR2_TEN; // disable TX 
    UART2->CR2 |=  UART2_CR2_REN; // enable RX   
    UART2_ITConfig(UART2_IT_RXNE_OR, ENABLE);
 
    while(packet_not_received)   /* Loop block the UART2_RX interrupt */ 
    { }
    Process_the_UART2_response();
}

[AA1 · Accepted solution]

The problem is a bad design. Interrupt handlers should be short and mus not have a wait loop. And don't mix UART code with TIMER code.

Interrupt handlers should not be used to do processing.

Of course the while loop in interrupt handler will block other interrupts because as is all interrupts have same priority,

[Kmax18]

Thank you for your feedback and recommendation.