diff --git a/src/config.rs b/src/config.rs
index 939a4ef..1a08346 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,5 +1,16 @@
+/// Firmware configuration values, hard coded.
+
+/// Address of SNTP server, as IPv4 address or FQDN.
 pub(crate) const SNTP_SERVER: &'static str = "time.nist.gov";
+
+/// Start of "on" cycle for switch, in 24 hour "HH:MM" format.
 pub(crate) const T_ON: &'static str = "17:00";
+
+/// End of "on" cycle for switch, in 24 hour "HH:MM" format.
 pub(crate) const T_OFF: &'static str = "09:00";
+
+/// Access point SSID.
 pub(crate) const WIFI_SSID: &'static str = "Example";
+
+/// WPA2 Personal password for access point.
 pub(crate) const WIFI_PASS: &'static str = "guest";
diff --git a/src/main.rs b/src/main.rs
index 3b58440..34f3896 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,7 +14,8 @@ use log::info;
 mod config;
 
 const SNTP_STATUS_POLL_INTVL_MS: u32 = 2000;
-const CONTROL_LOOP_INTVL_MS: u32 = 60000;
+/// Delay between executions of the main control loop, in milliseconds.
+const CONTROL_LOOP_INTVL: u32 = 60000;
 
 fn main() -> Result<()> {
     // It is necessary to call this function once. Otherwise some patches to
@@ -57,7 +58,7 @@ fn main() -> Result<()> {
         FreeRtos::delay_ms(SNTP_STATUS_POLL_INTVL_MS);
     }
 
-    // Main control loop:
+    // ======== Main Control Loop ======== //
     loop {
         let now = Utc::now().with_timezone(&Pacific);
         info!("Current time: {}", now);
@@ -84,7 +85,7 @@ fn main() -> Result<()> {
 
         // TODO: enter low power mode ("light sleep" or "deep sleep") instead
         // of waiting in normal mode.
-        FreeRtos::delay_ms(CONTROL_LOOP_INTVL_MS);
+        FreeRtos::delay_ms(CONTROL_LOOP_INTVL);
     }
 }