STM32F103 ZET6 Interrupts Not Triggering Common Mistakes and Fixes

STM32F103ZET6 Interrupts Not Triggering: Common Mistakes and Fixes

When working with the STM32F103ZET6 microcontroller, one of the most common issues developers face is that interrupts fail to trigger as expected. This can be frustrating and difficult to debug, but with some careful troubleshooting, you can quickly resolve the problem. Below are the common causes and step-by-step solutions to fix this issue.

Common Causes of Interrupts Not Triggering Interrupt Priority Misconfiguration STM32F103ZET6 uses a nested vector interrupt controller (NVIC), and interrupt priority needs to be properly configured. If the priority levels are not correctly set, higher-priority interrupts may block the lower-priority ones. Incorrect Peripheral Clock Settings Interrupts associated with peripherals (such as GPIO, timers, or UART) may fail to trigger if the associated peripheral's clock is disabled. This is a common oversight in initialization code. Incorrect NVIC Enablement Even if the interrupt is correctly configured, it won’t trigger unless it is enabled in the NVIC (Nested Vectored Interrupt Controller). If the interrupt is not enabled at the NVIC level, it will not be triggered. Interrupt Flag Not Cleared Some peripherals, such as timers and UARTs , require the interrupt flag to be cleared manually. If the flag isn't cleared, the interrupt may not be triggered again. Faulty GPIO Configuration for External Interrupts If you're using external interrupts (e.g., connected to a GPIO pin), it’s crucial to correctly configure the GPIO mode (input) and interrupt trigger condition (rising edge, falling edge, or both). Incorrect Handler or Interrupt Vector Table If the interrupt service routine (ISR) is not correctly linked to the interrupt vector table, the interrupt will not trigger. Ensure that the ISR is defined and connected properly in the vector table. Step-by-Step Troubleshooting and Fixes Check Peripheral Clock Enablement What to do: Ensure that the clock for the peripheral generating the interrupt is enabled. For example, if you're using a timer, verify that the timer's clock is enabled in the RCC (Reset and Clock Control) configuration. How to check: Use RCC_APB1PeriphClockCmd() or RCC_APB2PeriphClockCmd() to enable the appropriate clock. Verify NVIC Configuration What to do: Make sure that the interrupt is enabled in the NVIC and that it has the appropriate priority. How to check: c NVIC_EnableIRQ(TIM2_IRQn); // For example, enabling a Timer 2 interrupt NVIC_SetPriority(TIM2_IRQn, 1); // Set priority Ensure you enable the correct interrupt and set priorities properly. Configure GPIO for External Interrupts What to do: If using external interrupts (like on GPIO pins), ensure the GPIO pin is correctly configured as input and the interrupt is triggered on the correct edge (rising, falling, or both). How to check: Example for configuring GPIO for external interrupt on pin PA0: c GPIO_InitTypeDef GPIO_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_In_FLOATING; // or GPIO_Mode_IPU GPIO_Init(GPIOA, &GPIO_InitStructure); EXTI_InitTypeDef EXTI_InitStructure; EXTI_InitStructure.EXTI_Line = EXTI_Line0; EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; // Set edge trigger EXTI_InitStructure.EXTI_LineCmd = ENABLE; EXTI_Init(&EXTI_InitStructure); NVIC_EnableIRQ(EXTI0_IRQn); // Enable the interrupt for EXTI Line0 Clear Interrupt Flags What to do: Ensure that you clear the interrupt flag within the ISR to avoid missing future interrupts. If the flag isn’t cleared, the interrupt might not trigger again. How to check: For peripherals like timers or UARTs, check their specific interrupt flag and clear it. Example: c if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET) { // Clear the interrupt flag TIM_ClearITPendingBit(TIM2, TIM_IT_Update); // Your ISR code } Check Interrupt Handler in Vector Table What to do: Verify that the correct interrupt vector is mapped to the corresponding handler function. STM32 uses a vector table to link each interrupt to its corresponding ISR. How to check: Make sure your ISR function matches the interrupt vector name: c void TIM2_IRQHandler(void) { // Handle Timer 2 interrupt } Check for Nested Interrupts (If Using Multiple Interrupts) What to do: If your system uses multiple interrupts, ensure the interrupt priority and nesting behavior are configured correctly to prevent higher-priority interrupts from blocking others. How to check: In STM32, nested interrupt support can be configured via the NVIC. Double-check the priority levels for each interrupt to ensure proper execution order. Final Thoughts

By following these steps, you should be able to troubleshoot and resolve most issues where STM32F103ZET6 interrupts are not triggering. The key is ensuring that the peripherals, NVIC, and GPIO configurations are all correct. Careful attention to clock settings, interrupt priorities, and clearing interrupt flags will prevent most common mistakes.

If after all of these checks the interrupt still doesn’t trigger, consider reviewing your hardware connections (e.g., pull-up/down resistors, external interrupt sources) to ensure there are no physical issues.

Good luck with your debugging, and feel free to ask if you need further assistance!