diff --git a/gpio.c b/gpio.c
--- a/gpio.c
+++ b/gpio.c
@@ -4,8 +4,10 @@
 #include <inttypes.h>
 
 // Increase on each press, and increase at a fast rate after duration elapsed of continuously holding down... somehow...
-uint32_t change_time_reset = 0;
+static uint32_t change_time_reset = 0;
 
+
+// Increment/decrement unsigned variable with up/down buttons
 void user_input(uint16_t* to_modify)
 {
     if(CHANGE_ELAPSED) {
@@ -20,6 +22,8 @@ void user_input(uint16_t* to_modify)
     }
 }
 
+
+// Increment/decrement signed variable with up/down buttons
 void user_input_signed(int16_t* to_modify)
 {
     // TODO: Bounds check on int16_t
@@ -36,8 +40,9 @@ void user_input_signed(int16_t* to_modif
 }
 
 
-void gpio_init(void) {
-
+// Initialize GPIO
+void gpio_init(void)
+{
   GPIO_InitTypeDef GPIO_InitStruct;
 
     /* GPIO Ports Clock Enable */