@yubeer 在 t113-s3 RMII 网卡IP101GR不识别 中说:
@heyahong 没错,X1-X2是需要提供25MH在时钟源的,看了IP101GR的手册,25MHz时钟可以有外部晶振提供,也可以由外部时钟源提供连接X1,另外PHY50MHz时钟在RMII模式,可以由IP101内部提供。图应该没问题啊~
datasheet page-44
Reduced Media Independent Interface (RMII) is defined to provide a fewer pins data transmission
condition. The management interface, MDC and MDIO, are identical to the MII defined in IEEE 802.3.
RMII supports 10/100Mb data rates and the clock source are provided by a single 50MHz clock from
either external or within IP101G.
看图中的箭头方向,图中不正好说明CPU不产生时钟(接受时钟输入),X1-X2应该装无源晶振,只用X1应该装有源晶振而不是连在CPU上。