input capture indirect mode

[yang hong]

Posted on May 07, 2018 at 17:15

Hello, 

I am new in stm32. I am trying to configure timer. I don't understand input capture indirect mode. Does anybody know how to use it? I am trying TIM3, I found channel 3 can be input capture indirect mode.

thanks.

[Tesla DeLorean]

Posted on May 07, 2018 at 17:32

It defines the pin routing, with TIM3_CH3 direct mode would connect to the CH3 pin, indirect mode would connect to the CH4 pin.

[ANand3]

Input Capture Indirect Mode is when you want to take input from other channel. If you check out the Timer Cookbook (image from Timer Cookbook below). You will observe that TI1FP2 is connected to Channel 2, and similarly TI2FP1 is connected to Channel 1. This can also be observed with Channel 3 and 4.

Further, I found the comment from HAL.

#define TIM_ICSELECTION_INDIRECTTI         (TIM_CCMR1_CC1S_1)   /*!< TIM Input 1, 2, 3 or 4 is selected to be
                                                                     connected to IC2, IC1, IC4 or IC3, respectively */

I hope this explains the Input Capture Indirect Mode to you.

Application: You can use Channel 3 and 4, Channel 1 and 2 to get same signal.

[ANand3]

What is pin routing exactly? Does this mean that when I configure TIM3_CH3 in Input Capture Direct Mode, and TIM3_CH4 in Indirect Mode, I can read same signal in two different channels?