From 67d725d7cfa9881cc111683ed57a7bc18b95753f Mon Sep 17 00:00:00 2001
From: Theo Arends <11044339+arendst@users.noreply.github.com>
Date: Mon, 26 Sep 2022 14:06:28 +0200
Subject: [PATCH] Fix SR04 serial receive

Fix SR04 serial receive (#16613)
---
 tasmota/tasmota_xsns_sensor/xsns_22_sr04.ino | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tasmota/tasmota_xsns_sensor/xsns_22_sr04.ino b/tasmota/tasmota_xsns_sensor/xsns_22_sr04.ino
index 717f76566..85c13a97b 100644
--- a/tasmota/tasmota_xsns_sensor/xsns_22_sr04.ino
+++ b/tasmota/tasmota_xsns_sensor/xsns_22_sr04.ino
@@ -115,7 +115,7 @@ void Sr04TModeDetect(void) {
   if (!PinUsed(GPIO_SR04_ECHO)) { return; }
 
   int sr04_echo_pin = Pin(GPIO_SR04_ECHO);
-  int sr04_trig_pin = (PinUsed(GPIO_SR04_TRIG)) ? Pin(GPIO_SR04_TRIG) : Pin(GPIO_SR04_ECHO);   // if GPIO_SR04_TRIG is not configured use single PIN mode with GPIO_SR04_ECHO only
+  int sr04_trig_pin = Pin(GPIO_SR04_TRIG);  // if GPIO_SR04_TRIG is not configured use single PIN mode with GPIO_SR04_TRIG as -1
   sonar_serial = new TasmotaSerial(sr04_echo_pin, sr04_trig_pin, 1);
 
   if (sonar_serial && sonar_serial->begin(9600)) {
@@ -135,14 +135,17 @@ void Sr04TModeDetect(void) {
       delete sonar_serial;
       sonar_serial = nullptr;
     }
+    sr04_trig_pin = (PinUsed(GPIO_SR04_TRIG)) ? Pin(GPIO_SR04_TRIG) : Pin(GPIO_SR04_ECHO);  // if GPIO_SR04_TRIG is not configured use single PIN mode with GPIO_SR04_ECHO only
     sonar = new NewPing(sr04_trig_pin, sr04_echo_pin, SR04_MAX_SENSOR_DISTANCE);
     delay(100); // give time to inizialise, preventing ping_median fails
     if (!sonar || !sonar->ping_median(5)) {
       SR04.type = SR04_MODE_NONE;
     }
   } else {
-    if (sonar_serial->hardwareSerial()) {
-      ClaimSerial();
+    if (sonar_serial) {
+      if (sonar_serial->hardwareSerial()) {
+        ClaimSerial();
+      }
     }
   }