[STM32L053] TIM21 reload value

[stanzanim]

Posted on November 25, 2015 at 17:48

I cannot find any function which allow me to change the reload value (supposedly stored in ....Init.Period member of the timer struct). Should I rerun Cube MX and change the counter period in the the TIM21 settings panel? is there any drawback on changing this on the fly?

thanks

[Tesla DeLorean]

Posted on November 25, 2015 at 18:51

Couldn't you use something like TIM21->ARR = NewPeriod; ?

The preload settings would determine if this is taken immediately, or at the next update.

[stanzanim]

Posted on November 26, 2015 at 11:04

h

ello clive

I found this macro which does the job

  __HAL_TIM_SET_COMPARE(&htim21, 1, 6400/2);

Then I cannot make the OC feature for TIM21 working: I am having Nucleo64 (STM32L053) as target I want to use the TIM21 OC for generating a periodic square wave at PB13 (OC channel 1). I set up the project with CubeMX enabling TIM21 output compare etc.

To check the PB13 is alive I tried first to set the OCMODE to 'forced output'

  sConfigOC.OCMode = TIM_OCMODE_FORCED_ACTIVE;

I then was expecting PB13 goes high but this does not happen :(

I then went back to the option as generate by CubeMx

  sConfigOC.OCMode = TIM_OCMODE_TOGGLE;

I set AAR = 6400(htim21.Init.Period = 6400;)

and the comapre register at 3200 for channel 1

  __HAL_TIM_SET_COMPARE(&htim21, 1, 6400/2);

Before the while(1) loop I execute

 //HAL_TIM_Base_Start(&htim21);

 HAL_TIM_OC_Start(&htim21, 1);

expecting a waveform with 50%% duty cycle with 6400 clock cycle of period.

APB13=0 forever ...

please advice (I feel I am doing something completely wrong)