diff --git a/Kernel/kernel_M.c b/Kernel/kernel_M.c
index 24b72cb5ff359f8959f8640bb9af7d7e5dc26ec4..484766e8501e7694a9fb9df849fac08d45a2e008 100644
--- a/Kernel/kernel_M.c
+++ b/Kernel/kernel_M.c
@@ -20,6 +20,7 @@
 #define DEVICE_NAME "packet_receiver"
 #define CLASS_NAME  "packet_class"
 
+// cat /sys/kernel/debug/gpio
 #define GPIO_DATA 17  // GPIO for data transmission
 #define GPIO_CLOCK 27 // GPIO for clock control