Add baud rate check #254

examples/Arduino_AT_Debug/Arduino_AT_Debug.ino

@@ -16,6 +16,29 @@
 // Set serial for AT commands (to the module)
 #define SerialAT  Serial1
 
+uint32_t AutoBaud()
+{
+    static uint32_t rates[] = {115200, 9600, 57600,  38400, 19200,  74400, 74880,
+                               230400, 460800, 2400,  4800,  14400, 28800
+                              };
+    for (uint8_t i = 0; i < sizeof(rates) / sizeof(rates[0]); i++) {
+        uint32_t rate = rates[i];
+        Serial.printf("Trying baud rate %u\n", rate);
+        SerialAT.updateBaudRate(rate);
+        delay(10);
+        for (int j = 0; j < 10; j++) {
+            SerialAT.print("AT\r\n");
+            String input = SerialAT.readString();
+            if (input.indexOf("OK") >= 0) {
+                Serial.printf("Modem responded at rate:%u\n", rate);
+                return rate;
+            }
+        }
+    }
+    SerialAT.updateBaudRate(115200);
+    return 0;
+}
+
 void setupModem()
 {
 #ifdef MODEM_RST
@@ -47,11 +70,22 @@ void setup()
     // Set console baud rate
     SerialMon.begin(115200);
 
-    // Set GSM module baud rate and UART pins
-    SerialAT.begin(115200, SERIAL_8N1, MODEM_RX, MODEM_TX);
-
     setupModem();
 
+    if (AutoBaud()) {
+        Serial.println(F("***********************************************************"));
+        Serial.println(F(" You can now send AT commands"));
+        Serial.println(F(" Enter \"AT\" (without quotes), and you should see \"OK\""));
+        Serial.println(F(" If it doesn't work, select \"Both NL & CR\" in Serial Monitor"));
+        Serial.println(F(" DISCLAIMER: Entering AT commands without knowing what they do"));
+        Serial.println(F(" can have undesired consiquinces..."));
+        Serial.println(F("***********************************************************\n"));
+    } else {
+        Serial.println(F("***********************************************************"));
+        Serial.println(F(" Failed to connect to the modem! Check the baud and try again."));
+        Serial.println(F("***********************************************************\n"));
+    }
+
 }
 
 void loop()