diff --git a/libraries/SPI/examples/ADC_read_write_registers/ADC_read_write_registers.ino b/libraries/SPI/examples/ADC_read_write_registers/ADC_read_write_registers.ino
index 771a1cf..5d7f87d 100644
--- a/libraries/SPI/examples/ADC_read_write_registers/ADC_read_write_registers.ino
+++ b/libraries/SPI/examples/ADC_read_write_registers/ADC_read_write_registers.ino
@@ -5,7 +5,7 @@
 
 #include "SPI.h"
 
-#define CS_PIN        9
+#define CS_PIN        9 // P1_8
 
 // address of register to read and write
 const int reg_to_test = 0x03;