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LS1021A GPIO usage peculiarity

Question asked by fdm on Aug 16, 2017
Latest reply on Aug 28, 2017 by fdm

Hi,

 

There is some information concerning GPIO pins usage in LS1021A:

Based on feedback from SW/design team If we want use all the GPIO3, we should set all the GPIO3 pin by RCW.

Include: EC1,EC2,EC3 and MDC_MDIO. You don't have option to only select subset of the GPIO3 pins. This is applicable to all GPIO ports.

416-418 EC1 = 001 GPIO3[2:14]

419-421 EC2 =001 GPIO3[15:27]

422-424 EC3 =001 GPIO3[28:31]

425-426 MDC_MDIO =01 GPIO3[0:1]

Unfortunately this information not explained in the RM.

I am not sure if I understand this right. Is it mandatory to set all 4 groups of GPIO3 related RCW bits to the "GPIO" state in order to use only two GPIO3 pins (GPIO3_13 and GPIO3_14 in that use case), thus making e.g. eTSEC3 RGMII interface unusable?

 

In contrast with the foregoing, one of our custom LS1021A based boards successfully uses SDHC interface and GPIO2_24 pin as GPIO output simultaneously despite of the fact that GPIO2[4:9] pins are shared with SDHC.

 

As far as I know, this fact is not documented so far.

Is there any additional background info on this issue?

 

BR,
   Denis

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