From f445b5acdc17ee6664cee77d5b113e2e54412eb2 Mon Sep 17 00:00:00 2001
From: agessaman <adam@gessaman.com>
Date: Fri, 6 Feb 2026 16:31:20 -0800
Subject: [PATCH] fix(kiss_modem): improve RX delivery and noise floor sampling

---
 examples/kiss_modem/KissModem.cpp |  5 +++++
 examples/kiss_modem/KissModem.h   |  2 ++
 examples/kiss_modem/main.cpp      | 32 +++++++++++++++++++++----------
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/examples/kiss_modem/KissModem.cpp b/examples/kiss_modem/KissModem.cpp
index 31bb8a1e..94e4fe83 100644
--- a/examples/kiss_modem/KissModem.cpp
+++ b/examples/kiss_modem/KissModem.cpp
@@ -99,6 +99,11 @@ void KissModem::loop() {
 
     if (_rx_len < KISS_MAX_FRAME_SIZE) {
       _rx_buf[_rx_len++] = b;
+    } else {
+      /* Buffer full with no FEND; reset so we don't stay stuck ignoring input. */
+      _rx_len = 0;
+      _rx_escaped = false;
+      _rx_active = false;
     }
   }
 
diff --git a/examples/kiss_modem/KissModem.h b/examples/kiss_modem/KissModem.h
index 6b56b91e..674b68f7 100644
--- a/examples/kiss_modem/KissModem.h
+++ b/examples/kiss_modem/KissModem.h
@@ -197,4 +197,6 @@ public:
 
   void onPacketReceived(int8_t snr, int8_t rssi, const uint8_t* packet, uint16_t len);
   bool isTxBusy() const { return _tx_state != TX_IDLE; }
+  /** True only when radio is actually transmitting; use to skip recvRaw in main loop. */
+  bool isActuallyTransmitting() const { return _tx_state == TX_SENDING; }
 };
diff --git a/examples/kiss_modem/main.cpp b/examples/kiss_modem/main.cpp
index 62c1658f..adb20146 100644
--- a/examples/kiss_modem/main.cpp
+++ b/examples/kiss_modem/main.cpp
@@ -112,16 +112,12 @@ void setup() {
 void loop() {
   modem->loop();
 
-  if ((uint32_t)(millis() - next_noise_floor_calib_ms) >= NOISE_FLOOR_CALIB_INTERVAL_MS) {
-    radio_driver.triggerNoiseFloorCalibrate(0);
-    next_noise_floor_calib_ms = millis();
-  }
-  radio_driver.loop();
-
-  if (!modem->isTxBusy()) {
-    if ((uint32_t)(millis() - next_agc_reset_ms) >= AGC_RESET_INTERVAL_MS) {
-      radio_driver.resetAGC();
-      next_agc_reset_ms = millis();
+  if (!modem->isActuallyTransmitting()) {
+    if (!modem->isTxBusy()) {
+      if ((uint32_t)(millis() - next_agc_reset_ms) >= AGC_RESET_INTERVAL_MS) {
+        radio_driver.resetAGC();
+        next_agc_reset_ms = millis();
+      }
     }
 
     uint8_t rx_buf[256];
@@ -131,5 +127,21 @@ void loop() {
       int8_t rssi = (int8_t)radio_driver.getLastRSSI();
       modem->onPacketReceived(snr, rssi, rx_buf, rx_len);
     }
+    /* Sample noise floor right after drain: we're in STATE_RX so wrapper can collect. */
+    for (int i = 0; i < 16; i++) {
+      radio_driver.loop();
+    }
+  }
+
+  /* Trigger starts a new 64-sample calibration window every 2s. */
+  if ((uint32_t)(millis() - next_noise_floor_calib_ms) >= NOISE_FLOOR_CALIB_INTERVAL_MS) {
+    radio_driver.triggerNoiseFloorCalibrate(0);
+    next_noise_floor_calib_ms = millis();
+  }
+  radio_driver.loop();
+  if (!modem->isActuallyTransmitting()) {
+    for (int i = 0; i < 15; i++) {
+      radio_driver.loop();
+    }
   }
 }