Add an rx only example

examples/RX_only/RX_only.pde

@@ -0,0 +1,65 @@
+/**
+ * Example code for using a microchip mrf24j40 module in receive mode only
+ * packets using plain 802.15.4
+ * Requirements: 3 pins for spi, 3 pins for reset, chip select and interrupt
+ * notifications
+ * This example file is considered to be in the public domain
+ * Originally written by Karl Palsson, karlp@tweak.net.au, March 2011
+ */
+#include <SPI.h>
+#include <mrf24j.h>
+
+const int pin_reset = 6;
+const int pin_cs = 7;
+const int pin_interrupt = 5;
+
+Mrf24j mrf(pin_reset, pin_cs, pin_interrupt);
+
+void setup() {
+  Serial.begin(9600);
+
+  mrf.set_pan(0xcafe);
+  // This is _our_ address
+  mrf.address16_write(0x6001); 
+
+  // uncomment if you want to receive any packet on this channel
+  // mrf.set_promiscuous(true);
+
+  attachInterrupt(0, interrupt_routine, CHANGE);   
+  interrupts();
+}
+
+volatile byte gotrx;
+
+void interrupt_routine() {
+    // read and clear from the radio
+    byte last_interrupt = mrf.read_short(MRF_INTSTAT);
+    if (last_interrupt & MRF_I_RXIF) {
+        gotrx = 1;
+    }
+}
+
+void loop() {
+    int tmp;
+    if (gotrx) {
+        gotrx = 0;
+        noInterrupts();
+        mrf.write_short(MRF_BBREG1, 0x04);  // RXDECINV - disable receiver
+
+        byte frame_length = mrf.read_long(0x300);  // read start of rxfifo
+        Serial.print("received a packet ");Serial.print(frame_length, DEC);Serial.println(" bytes long");
+        Serial.println("Packet data:");
+        for (int i = 1; i <= frame_length; i++) {
+            tmp = mrf.read_long(0x300 + i);
+            Serial.print(tmp, HEX);
+        }
+        Serial.print("\r\nLQI/RSSI=");
+        byte lqi = mrf.read_long(0x300 + frame_length + 1);
+        byte rssi = mrf.read_long(0x300 + frame_length + 2);
+        Serial.print(lqi, HEX);
+        Serial.println(rssi, HEX);
+
+        mrf.write_short(MRF_BBREG1, 0x00);  // RXDECINV - enable receiver
+        interrupts();
+    }
+}