[GitHub] [incubator-nuttx] davids5 opened a new pull request #6: STM32F7 and STM32H7 SDMMC internal pull up usage fixed

[GitBox]

davids5 opened a new pull request #6: STM32F7 and STM32H7 SDMMC internal pull 
up usage fixed
URL: https://github.com/apache/incubator-nuttx/pull/6
 
 
   
    -   Code was flawed in that the Pins are defined with the
      pullups in the definition. Since there are no alterntes pins
      there is no way to remove them. So not enabling the CONFIG
      pull up did nothing as did enabling them.
   
    -  This is now a compile time feature as there was no reason for
      it to be a run time. It wasted both flash and ram.
   
     - The code ignored the use of D0 for ready detection causing
      3X+ the chatter.
   
   No Internal PU and 100K External Note 2.5 us of chatter
    
   
![image](https://user-images.githubusercontent.com/1945821/71418551-d3f34a80-261f-11ea-990c-d4552cbaaff3.png)
   
   With Internal PU and 100K External Note 0.7 us of chatter
    
   
![image](https://user-images.githubusercontent.com/1945821/71418554-d6ee3b00-261f-11ea-8b4a-9d755b9b9f05.png)
   

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