For next overflow triggering interrupt, the LED levels will switch again. And the program will jump to the interrupt service function, in which the LEDs levels will have a switch. Since we have enabled the timer interrupt, the overflow event may trigger a timer interrupt. The counter count from 0 to 10000-1(9999), generate a counter overflow event, then counts from 0 again. In the main() routine, call HAL_TIM_Base_Start_IT(&htim3) to enable the timer. If the timer is set to 1s, auto-reload register should be set to 10000-1. The timer frequency is 10000Hz, which means each pulse has 1/10000s. The timer mode is set to upcounting mode and prescaler register is set to 10800-1 (10800 division). In the TIM3 timer configuration, select internal clock with no frequency division as clock source, and mount it to the APB1 clock bus (108MHz). If the program has no error, you can see the LED1~LED4blink once pre second when pressing the key WAKEUP.
How to set up eon timer gen 4 code#
*#-1- Start the TIM Base generation in interrupt mode #*/Ĭompile the program again, and download the compiled code to the Open746-C development board. In the main.c file, add the following code before the while(1) loop, to start the TIM Base generation in interrupt mode. Void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim) * Period elapsed callback in non blocking mode Add the interrupt callback function in the middle of USER CODE BEGIN 4 andUSER CODE END 4 after the file main.c.Intimer interrupt handler function, the levels of LED1~LED4 may have a switch.
Open the file main.c, delete the chapter of lines above the while loop in the main() routine, and make sure the while loop is empty. You can regenerate a new report and a new code, then compile the program.
Or, you can enable TIM3 interrupt in NVIC configuration. The priority configurations are remain in default settings. Under the tab NVIC Settings, check the Enabled checkbox to enable the timer interrupt. In center-aligned mode, the counter counts from 0 to the auto-reload value (content of the TIMx_ARR register) - 1, generates a counter overflow event, then counts from the auto-reload value down to 1 and generates a counter underflow event. In downcounting mode, the counter counts from the auto-reload value (content of theTIMx_ARR register) down to 0, then restarts from the auto-reload value and generates acounter underflow event. In upcounting mode, the counter counts from 0 to the auto-reload value (content of theTIMx_ARR register), then restarts from 0 and generates a counter overflow event. So the relative parameters are default setting. However, this function is not in used in here. In this case, auto-reload register (TIMx_ARR) is set to 10000-1, which means the timer is set to 1s.TRGO is a trigger output, which can trigger internal ADC/DAC. (The prescaler register (TIMx_PSC) is set to 10800-1), and the frequency of the CK_CNT is 10000Hz. In case that the timer is set to 1s, the internal clock can be set to 10800 division. When the internal clock is set to CKD, the CK_PSC clock frequency is equal to the clock frequency of APB1 (108MHz or108000 000Hz). By reading the relative datasheet or viewing the code, you can find that the TIM3 is connected to APB1 clock line. In the TIM3 configuration, select internal clock as the clock source. You should set the CK_PSC frequency to make sure the time set by the timer. See Figure 194 in File:STM32F7-Reference-EN.pdf In fact, the overflow event may be triggered every 37 pulses (the counter begin from 0). For example, as the figure194 shows, when the counter increase to 36, it will overflow and trigger an interrupt event.
See Figure 192 in File:STM32F7-Reference-EN.pdfĪuto-reload register (TIMx_ARR) stores the overflow value of the counter. In case that frequency is required to be divided by 10000, the prescaler value should be set to 10000-1. And the prescaler register(TIMx_PSC) value define the counter behavior with the specific SK_PSC pulse number.As the figure192 shows, the prescaler value is 1, it means the counter may add 1 every two pulses, frequency is divided by 2 (the prescaler register is set to 0 by default, which means no frequency division). Counter timing diagram, internal clock divided by 1Ĭounter register(TIMx_CNT) stores the current count value.
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