GPIO-Usage-&-Used-Pins.md

@@ -4,7 +4,7 @@ GPIOs are grouped in ports and so each GPIO has an identifier.
 The identifiers have the following format: `PXY`, where `X` is the GPIO port name and `Y` is the pin number.
 
 ## Introduction
-GPIO ports' registers are mapped to well defined memory addresses. This means that by accessing those addresses, we can access the GPIO registers.  
+GPIO ports' registers are mapped to well defined memory addresses. This means that by accessing those addresses, we directly access the GPIO registers.  
 Then, we can define a structure that represents the memory layout of the GPIO registers:
 ```cpp
 typedef struct
@@ -171,7 +171,7 @@ These are some pins that are used by default from the kernel when running on _ST
 Extra
 ---------------
 
-## STM32F429ZI Discovery Pins
+#### STM32F429ZI Discovery Pins
 
 ![alt-img](https://os.mbed.com/media/uploads/bcostm/disco_f429zi_2017-07-25_slide1.png)
 ![alt-img](https://os.mbed.com/media/uploads/bcostm/disco_f429zi_2017-07-25_slide2.png)
\ No newline at end of file