feat(examples): add an example for switching between multiple software serial devices

Author: asas1asas200

examples/multiple_software_serials/multiple_software_serials.ino

@@ -0,0 +1,77 @@
+/*
+ * A simple example to interface with multiple software serials.
+ * Use multiple software serials on some boards can only listen one UART at a time like Uno.
+ * 
+ * Note:
+ *     You can use it for connect other software serials devices not only rdm6300.
+ *     In these case, we use two rdm6300 readers for example.
+ * 
+ *     The LED pin of rdm6300 is set at 5V (HIGH) at initial, 
+ *     and if an RFID was read, the LED pin goes to 0V (LOW) for some moments.
+ *     We can use this property to switch between two devices,
+ *     but it still can only read from a device at a time.
+ * 
+ *     And be aware about usage of listening switch between devices.
+ * 
+ * Connections:
+ *     | Uno | rdm6300-1 | rdm6300-2 | notes                               |
+ *     |-----+-----------+-----------+-------------------------------------|
+ *     | D5  | TX        |           |                                     |
+ *     | D6  | LED       |           |                                     |
+ *     | D7  |           | TX        |                                     |
+ *     | D8  |           | LED       |                                     |
+ *     | GND | GND       | GND       |                                     |
+ *     | VCC | VCC       | VCC       | The rdm6300 must be powered with 5V |
+ * 
+ * Zeng (https://github.com/asas1asas200)
+ */
+
+#include <rdm6300.h>
+
+#define RDM6300_1_RX_PIN	5
+#define RDM6300_1_LED_PIN	6
+#define RDM6300_2_RX_PIN	7
+#define RDM6300_2_LED_PIN	8
+
+Rdm6300 rdm6300_1;
+Rdm6300 rdm6300_2;
+
+Rdm6300 *current_rdm6300;
+
+void setup()
+{
+	Serial.begin(115200);
+	pinMode(RDM6300_1_LED_PIN, INPUT);
+	pinMode(RDM6300_2_LED_PIN, INPUT);
+
+	rdm6300_1.begin(RDM6300_1_RX_PIN);
+	rdm6300_2.begin(RDM6300_2_RX_PIN);
+
+	rdm6300_1.listen();
+	current_rdm6300 = &rdm6300_1;
+
+	Serial.println("Place RFID tag near any rdm6300...");
+}
+
+void loop()
+{
+	// checkout listening if needed
+	if (digitalRead(RDM6300_1_LED_PIN) == LOW
+			&& !rdm6300_1.is_listening()) {
+		Serial.println("Switch to listening RDM6300_1");
+		rdm6300_1.listen();
+		current_rdm6300 = &rdm6300_1;
+	} else if (digitalRead(RDM6300_2_LED_PIN) == LOW
+			&& !rdm6300_2.is_listening()) {
+		Serial.println("Switch to listening RDM6300_2");
+		rdm6300_2.listen();
+		current_rdm6300 = &rdm6300_2;
+	}
+
+	/* If you use rdm6300 with other devices, you had better set a TIMEOUT and run a while-loop to
+		make sure the tag can be read correctely. */
+	if (current_rdm6300->update()) 
+		Serial.println(current_rdm6300->get_tag_id(), HEX);
+	
+	delay(10);
+}