From 73abecfdb55032959559a999e91bf85a3e2b7e9b Mon Sep 17 00:00:00 2001
From: Stephen Waits <steve@waits.net>
Date: Sun, 29 Mar 2026 21:50:44 -0600
Subject: [PATCH] docs: document NO_SIGNAL sentinel and DTR polling interval

---
 src/display/task.rs | 3 ++-
 src/usb/task.rs     | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/display/task.rs b/src/display/task.rs
index e440e2ba..c6592c39 100644
--- a/src/display/task.rs
+++ b/src/display/task.rs
@@ -24,7 +24,8 @@ const BOARD_NAME: &str = if cfg!(feature = "rak_wisblock_4631") {
 /// Duration per sparkline slot. 64 slots * 1s = ~1 minute of history.
 const SPARK_SLOT_MS: u64 = 1000;
 
-/// Sentinel: no packet received in this slot.
+/// Sentinel: no packet received in this slot. Below SX1262 sensitivity
+/// floor (-120 dBm), so it cannot be confused with a real RSSI value.
 const NO_SIGNAL: i16 = -121;
 
 struct DisplayState {
diff --git a/src/usb/task.rs b/src/usb/task.rs
index a4e8e1e7..9fa8a780 100644
--- a/src/usb/task.rs
+++ b/src/usb/task.rs
@@ -105,7 +105,7 @@ async fn protocol_loop<'d, D: embassy_usb_driver::Driver<'d>>(
         match select3(
             receiver.read_packet(&mut read_buf),
             responses.receive(),
-            embassy_time::Timer::after_millis(250),
+            embassy_time::Timer::after_millis(250), // DTR poll interval for disconnect detection
         )
         .await
         {