在F302数据手册中
Bits 23:22 ENCODER_MODE: Encoder mode
This bit is set and cleared by software.
00: No redirection.
01: TIM2 IC1 and TIM2 IC2 are connected to TIM15 IC1 and TIM15 IC2 respectively.
10: TIM3 IC1 and TIM3 IC2 are connected to TIM15 IC1 and TIM15 IC2
respectively (STM32F302xB/C devices only).
11: TIM4 IC1 and TIM4 IC2 are connected to TIM15 IC1 and TIM15 IC2
respectively(STM32F302xB/C devices only).
Bit 21 I2C2_FMP: I2C2 fast mode Plus driving capability

这里有提到编码器模式，但TIM15定时器没有编码器接口，没有看懂这段话的意思，有谁知道是什么意思吗，这个功能有什么作用，以及如何使用这个功能？