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DP83867IS: GPIO configuration

Oba
Genius 17435 points


Hello

 

I have a question about LED configuration of DP83867.

 

GPIO_1 can be assigned as “COL” by setting GPIO_1_CTRL bit in GPIO_MUX_CTRL(0x0172) as 0000:COL.

On the other hand, GPIO_1 can be assigned as “LED_3” by setting GPIO_1_CTRL bit in GPIO_MUX_CTRL(0x0172) as 0110: LED_3

And also this GPIO_1 assigned as “LED_3” can be assigned as “0100: Collision detected” by setting LED_GPIO_SEL bit in LEDCR1(0x0018).

 

Then I would like to know the difference between

 

GPIO_MUX_CTRL(0x0172): GPIO_1_CTRL=0000:COL

and

GPIO_MUX_CTRL(0x0172): GPIO_1_CTRL=0110: LED_3 & LEDCR1(0x0018) : LED_GPIO_SEL = 0100: Collision detected

 

Regards,

Oba

  • 0
    TI__Mastermind 23675 points
    Hi Oba,

    Register 0x172 'COL' is the actual Collision pin function as defined in IEEE.
    This is used for half duplex operation.

    LED_3 set as COL indication is just an indication through LED that a collision has occurred. It does not follow the same behavior as IEEE because the COL indication on LED is elongated so that you can see it.

    One is an actual COL pin function and the other is visual indication.