Lan8720 interrupt pin

[totti001]

Posted on March 03, 2014 at 16:35

Hello everybody.

I want to use lan8720 ethernet interface with the interrupt pin. But the interrupt pin is the same with the refclk out. So if I use anexternal 25Mhz clock, or the stm32f4 mco pin, need to connect the reclk to the controller RMII_REF_CLK pin. What is the best way to use IT pin? Use an external 50MHz clock for lan8720 or use this clock for the controller too. In the stm32f4xx datasheet figure 91, an 50Mhz use for this, but in the clock configuration tool max HSE value is 26Mhz. #stm32f4-lan8720-interrupt-mco

[Tesla DeLorean]

Posted on March 03, 2014 at 16:52

Yes, HSE is limited/spec'd to have a max of 26 MHz (32 MHz on some other STM32 series parts).

Where a 50 MHz output is required, the MCO pin is configured to generate such. Either with an internal PLL/CPU clock of say 150 MHz (divisible by 50), or perhaps via MCO2 and the I2SPLL?

[totti001]

Posted on March 03, 2014 at 17:01

Thanks. So the MCO pin can generate 50Mhz clock output? This function need limitation at the controller? So I can't use some periphial, or 168MHz cpu clock? And what files need to modified for this?