diff --git a/config.h b/config.h
--- a/config.h
+++ b/config.h
@@ -1,12 +1,24 @@
 #ifndef CONFIG_H
 #define CONFIG_H
 
+// Temperature sensor type
+#define MAX31855_TC_SENSOR
+//#define MAX31865_RTD_SENSOR
+
+
+// Virtual serial port transmit rate
 #define VCP_TX_FREQ 1000
+
+// Solid-state relay maximum on-time
 #define SSR_PERIOD 200
+
+// Interval of PID calculations
 #define PID_PERIOD 120
 
+
+
+// Pin settings
 #define LED_POWER GPIOF,GPIO_PIN_0
-
 #define MAX_CS GPIOA,GPIO_PIN_15
 
 #define SW_BTN  GPIOB, GPIO_PIN_4