Add Serial buffer overrun detection

Add Serial buffer overrun detection and fix serial corruption by increasing uart serial buffer to 520

tasmota/support_tasmota.ino

@@ -1227,6 +1227,17 @@ void SerialInput(void)
     delay(0);
     serial_in_byte = Serial.read();
 
+    if (0 == serial_in_byte_counter) {
+      serial_buffer_overrun = false;
+    }
+    else if ((serial_in_byte_counter == INPUT_BUFFER_SIZE)
+#ifdef ESP8266
+//             || Serial.hasOverrun()  // Default ESP8266 Serial buffer size is 256. Tasmota increases to INPUT_BUFFER_SIZE
+#endif
+                                                             ) {
+      serial_buffer_overrun = true;
+    }
+
 #ifdef ESP8266
 /*-------------------------------------------------------------------------------------------*\
  * Sonoff dual and ch4 19200 baud serial interface
@@ -1255,7 +1266,7 @@ void SerialInput(void)
         if (serial_in_byte_counter < INPUT_BUFFER_SIZE -1) {                     // Add char to string if it still fits
           serial_in_buffer[serial_in_byte_counter++] = serial_in_byte;
         } else {
-          serial_in_byte_counter = 0;
+          serial_buffer_overrun = true;                                          // Signal overrun but continue reading input to flush until '\n' (EOL)
         }
       }
     } else {
@@ -1292,8 +1303,12 @@ void SerialInput(void)
     if (!Settings.flag.mqtt_serial && (serial_in_byte == '\n')) {                // CMND_SERIALSEND and CMND_SERIALLOG
       serial_in_buffer[serial_in_byte_counter] = 0;                              // Serial data completed
       seriallog_level = (Settings.seriallog_level < LOG_LEVEL_INFO) ? (uint8_t)LOG_LEVEL_INFO : Settings.seriallog_level;
-      AddLog_P2(LOG_LEVEL_INFO, PSTR(D_LOG_COMMAND "%s"), serial_in_buffer);
-      ExecuteCommand(serial_in_buffer, SRC_SERIAL);
+      if (serial_buffer_overrun) {
+        AddLog_P2(LOG_LEVEL_INFO, PSTR(D_LOG_COMMAND "Serial buffer overrun"));
+      } else {
+        AddLog_P2(LOG_LEVEL_INFO, PSTR(D_LOG_COMMAND "%s"), serial_in_buffer);
+        ExecuteCommand(serial_in_buffer, SRC_SERIAL);
+      }
       serial_in_byte_counter = 0;
       serial_polling_window = 0;
       Serial.flush();

tasmota/tasmota.h

@@ -124,7 +124,7 @@ const uint16_t SYSLOG_TIMER = 600;          // Seconds to restore syslog_level
 const uint16_t SERIALLOG_TIMER = 600;       // Seconds to disable SerialLog
 const uint8_t OTA_ATTEMPTS = 5;             // Number of times to try fetching the new firmware
 
-const uint16_t INPUT_BUFFER_SIZE = 520;     // Max number of characters in (serial and http) command buffer
+const uint16_t INPUT_BUFFER_SIZE = 520;     // Max number of characters in serial command buffer
 const uint16_t FLOATSZ = 16;                // Max number of characters in float result from dtostrfd (max 32)
 const uint16_t CMDSZ = 24;                  // Max number of characters in command
 const uint16_t TOPSZ = 151;                 // Max number of characters in topic string

tasmota/tasmota.ino

@@ -156,7 +156,8 @@ uint8_t last_source = 0;                    // Last command source
 uint8_t shutters_present = 0;               // Number of actual define shutters
 uint8_t prepped_loglevel = 0;               // Delayed log level message
 //uint8_t mdns_delayed_start = 0;             // mDNS delayed start
-bool serial_local = false;                  // Handle serial locally;
+bool serial_local = false;                  // Handle serial locally
+bool serial_buffer_overrun = false;         // Serial buffer overrun
 bool fallback_topic_flag = false;           // Use Topic or FallbackTopic
 bool backlog_mutex = false;                 // Command backlog pending
 bool interlock_mutex = false;               // Interlock power command pending
@@ -215,6 +216,7 @@ void setup(void)
   RtcRebootSave();
 
   Serial.begin(APP_BAUDRATE);
+  Serial.setRxBufferSize(INPUT_BUFFER_SIZE);  // Default is 256 chars
   seriallog_level = LOG_LEVEL_INFO;  // Allow specific serial messages until config loaded
 
   snprintf_P(my_version, sizeof(my_version), PSTR("%d.%d.%d"), VERSION >> 24 & 0xff, VERSION >> 16 & 0xff, VERSION >> 8 & 0xff);  // Release version 6.3.0

tasmota/xdrv_99_debug.ino

@@ -59,13 +59,14 @@
 #define D_CMND_I2CREAD   "I2CRead"
 #define D_CMND_I2CSTRETCH "I2CStretch"
 #define D_CMND_I2CCLOCK  "I2CClock"
+#define D_CMND_SERBUFF   "SerBufSize"
 
 const char kDebugCommands[] PROGMEM = "|"  // No prefix
   D_CMND_CFGDUMP "|" D_CMND_CFGPEEK "|" D_CMND_CFGPOKE "|"
 #ifdef USE_WEBSERVER
   D_CMND_CFGXOR "|"
 #endif
-  D_CMND_CPUCHECK "|"
+  D_CMND_CPUCHECK "|" D_CMND_SERBUFF "|"
 #ifdef DEBUG_THEO
   D_CMND_EXCEPTION "|"
 #endif
@@ -80,7 +81,7 @@ void (* const DebugCommand[])(void) PROGMEM = {
 #ifdef USE_WEBSERVER
   &CmndCfgXor,
 #endif
-  &CmndCpuCheck,
+  &CmndCpuCheck, &CmndSerBufSize,
 #ifdef DEBUG_THEO
   &CmndException,
 #endif
@@ -479,6 +480,18 @@ void CmndCpuCheck(void)
   ResponseCmndNumber(CPU_load_check);
 }
 
+void CmndSerBufSize(void)
+{
+  if (XdrvMailbox.data_len > 0) {
+    Serial.setRxBufferSize(XdrvMailbox.payload);
+  }
+#ifdef ESP8266
+  ResponseCmndNumber(Serial.getRxBufferSize());
+#else
+  ResponseCmndDone();
+#endif
+}
+
 void CmndFreemem(void)
 {
   if (XdrvMailbox.data_len > 0) {