Skip to main content
SWenn.1
Senior III
January 19, 2023
Solved

???ARPE (auto reload preload) STM32L476

  • January 19, 2023
  • 2 replies
  • 1004 views

Been looking closely at RM figures 342 AND 343.....I cannot see the value of the ARPE bit....when 1 it looks like the shadow register updates on UEV / or Interrupt and when 0 what?? 342 disregards showing the shadow register and on top of this who cares that it loads early when ARPE = 0.....

Can someone please explain the value of this bit?

This topic has been closed for replies.
Best answer by waclawek.jan

Effect of ARPE gets visible most if you write ARR to a value lower than is the current value of CNT. In that case, as Update occurs when CNT==ARR, timer keeps counting up until it reaches its top value (0xFFFF or 0xFFFF'FFFF) and rolls over to 0.

More nuanced uses of ARPE involve simultaneous writes to ARR and CCRx, synchronized actions on several timers, etc.

JW

2 replies

waclawek.jan
waclawek.janBest answer
Super User
January 19, 2023

Effect of ARPE gets visible most if you write ARR to a value lower than is the current value of CNT. In that case, as Update occurs when CNT==ARR, timer keeps counting up until it reaches its top value (0xFFFF or 0xFFFF'FFFF) and rolls over to 0.

More nuanced uses of ARPE involve simultaneous writes to ARR and CCRx, synchronized actions on several timers, etc.

JW

SWenn.1
SWenn.1Author
Senior III
January 19, 2023

Understood .....thank you