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M
mcagriaksoy
Associate III
May 11, 2026
Question

STM32 Encoder Mode vs Remap CH1, CH2 vs Index Mode

  • May 11, 2026
  • 3 replies
  • 124 views

Hi,

I am using two rotary encoders on an STM32U5G9ZJT.

Currently I have:
- TIM8_CH1 and CH2 available
- TIM3_CH3 and CH4 available

I know that standard encoder mode uses CH1 and CH2.

CubeMX shows options like:
- Encoder Mode (with remap CH1/CH2)
- Encoder Mode + Index (with remap CH1/CH2 + ETR)

My encoders are simple mechanical rotary encoders.

Question:
Should I use "Encoder Mode with remap" to map CH3/CH4 to CH1/CH2,
or is there any benefit to using "Encoder Mode + Index"?

 

Is there any difference, If I use "TIM8 in encoder mode" or "TIM3 encoder mode from remap"

Thanks!

3 replies

waclawek.jan
waclawek.jan
Super User
May 11, 2026

There's no point using the "Encoder+Index" mode if you don't have an encoder with an index output.

You cannot use TIMx_CH3/CH4 for Encoder. Fullstop.

waclawekjan_0-1778511385009.png

 

JW

M
mcagriaksoyAuthor
Associate III
May 12, 2026

Thanks for your answer,
You mean that the "Encoder Mode with remap" does not mean that we can use CH3 and CH4 for the quadrature encoder inputs, did I understand correctly?

So, may I ask, what does "Encoder Mode with remap" means? 


waclawek.jan
waclawek.jan
Super User
May 12, 2026

> what does "Encoder Mode with remap" mean?

I don't know. There is no such expression in the Reference Manual nor Datasheet for the 'U5. My guess is you have it from CubeMX. I don't use Cube/CubeMX. Cube/CubeMX developers sometimes "invent" terminology which does not match the chips' documentation. You may want to review CubeMX documentation. Or maybe somebody who uses Cube/CubeMX will chime it with the explanation.

In the ancient 'F1 family, there was this "remap" concept related to which pin pair was assigned to TIMx_CH1/CH2, but in all other families, there's no such concept.

JW

 

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