diff --git a/TESTS/receiver/simple/main.cpp b/TESTS/receiver/simple/main.cpp
new file mode 100644
index 0000000..15cfc28
--- /dev/null
+++ b/TESTS/receiver/simple/main.cpp
@@ -0,0 +1,37 @@
+/*
+  TESTS/receiver/simple/main.cpp
+  Spektrum receiver test
+  D Evangelista, 2018
+*/
+
+#include "mbed.h"
+#include "rtos.h"
+#include "spektrum.h"
+#include "unity.h"
+
+Serial pc(USBTX, USBRX);
+Spektrum receiver(p13, p14); 
+char c;
+
+
+
+int main(){
+
+  pc.printf("Spektrum receiver simple test\r\n");
+  pc.printf("Be sure to connect orange to p13, gray to p14, blk to gnd\r\n");
+  pc.printf("Receiver should have already been bound to transmitter\r\n");
+  
+  pc.printf("Successful (y/n)? ");
+  pc.scanf(" %c",&c);
+  TEST_ASSERT_EQUAL_MESSAGE('y',c,"receiver simple test failed.\r\n");
+
+} // main() for TESTS/receiver/simple
+
+
+
+
+
+
+
+
+
diff --git a/mbed-os.lib b/mbed-os.lib
index 31ac1c1..f55436f 100644
--- a/mbed-os.lib
+++ b/mbed-os.lib
@@ -1 +1 @@
-https://github.com/ARMmbed/mbed-os/#bfb43799afe571b26895d021f9932c274cff58c6
+https://github.com/ARMmbed/mbed-os/#aab3ade2b7b38996fd73b855f1c5bc46e2877313
diff --git a/spektrum.cpp b/spektrum.cpp
index 1db8c14..ae16795 100644
--- a/spektrum.cpp
+++ b/spektrum.cpp
@@ -10,13 +10,20 @@
 
    The receiver should first be bound using a BindPlug object. 
 */
-Spektrum::Spektrum(PinName tx, PinName rx): _receiver(tx, rx){
+Spektrum::Spektrum(PinName tx, PinName rx, PinName rx_led): _receiver(tx, rx), _rx_led(rx_led){
   _receiver.baud(SPEKTRUM_BAUD); // Spektrum uses 125000 8N1 or 115200 8N1
+
+  _receiver.attach(callback(this,&Spektrum::_rx_callback)); 
 } // Spektrum(tx, rx) constructor
 
 Spektrum::~Spektrum(){
 } // ~Spektrum() destructor
 
+void Spektrum::_rx_callback(void){
+  _rx_led.write(!_rx_led.read());
+  _buf[_i] = _receiver.getc();
+  _i = (_i+1) % SPEKTRUM_PACKET_SIZE;
+} // _packet_callback() 
 
 
 
diff --git a/spektrum.h b/spektrum.h
index 08b6879..18ef8f5 100644
--- a/spektrum.h
+++ b/spektrum.h
@@ -10,6 +10,7 @@
 #define SPEKTRUM_INT_DSMX_11MS 9
 #define SPEKTRUM_EXT_DSMX_11MS 10
 // DSM2 bind modes not recommended, not implemented
+// EXT(ernal) bind modes don't really work on solitary satellite receiver
 
 // field definitions
 // #define SPEKTRUM_MASK_1024_CHANID 0xfc00
@@ -27,19 +28,23 @@
 #define SPEKTRUM_BAUD 125000
 // Spektrum baud is 125000, but if this doesn't work 115200 should work too. 
 
-
+#define SPEKTRUM_PACKET_SIZE 16
 
 class Spektrum{
  public:
-  unsigned int fades; 
   unsigned int system; 
-  unsigned int servo[7];
-  bool is_bound;
-  Spektrum(PinName tx, PinName rx); // constructor
+  unsigned int fades; 
+  unsigned int channel[12];
+  Spektrum(PinName tx, PinName rx, PinName rx_led=LED1); // constructor
   ~Spektrum(); // destructor
 
  private:
   Serial _receiver;
+  DigitalOut _rx_led;
+  
+  char _buf[SPEKTRUM_PACKET_SIZE];
+  int _i; 
+  void _rx_callback(void); 
 };