STM32 - TIM2_ETR 引脚，连接到引脚 PA0（按钮），以奇怪的方式递增定时器

Question

I am trying to implement PWM LED dimming in 6 stages, where each stage in more bright, based on clicking button, which increments external pin, which serves the value to timer.

I am facing a problem, that sometimes, value variable is too large than it should be and skips some levels of brightness. For example, value increments: 1,2,3, then jumps to 6,7, etc.

Can anybody pinpoint where is the mistake I am making. Here is the code:

//EDIT: code removed, because it is a school assignment

Answer 1

This looks like contact bouncing. When input is processed by the CPU, a simple way to solve it is to disable input for a certain duration after an event is detected. Since you directly control timer input from a button, you may not have much control. However, I would experiment with the ETF field of the SMCR register (which in your case is likely set by the sClockSourceConfig.ClockFilter field) and the clock divisor CKD of the CR1 register (which seems like htim2.Init.ClockDivision in your code) (sorry, I am not familiar with STM libraries).