diff --git a/gpio.c b/gpio.c
--- a/gpio.c
+++ b/gpio.c
@@ -20,6 +20,21 @@ void user_input(uint16_t* to_modify)
     }
 }
 
+void user_input_signed(int16_t* to_modify)
+{
+    // TODO: Bounds check on int16_t
+    if(CHANGE_ELAPSED) {
+        if(!HAL_GPIO_ReadPin(SW_UP) ) {
+            CHANGE_RESET;
+            (*to_modify)++;
+        }
+        else if(!HAL_GPIO_ReadPin(SW_DOWN)) {
+            CHANGE_RESET;
+            (*to_modify)--;
+        }
+    }
+}
+
 
 void init_gpio(void) {