diff -r 162fe523c37d -r 4fd621551d55 src/hp34comm.h
--- a/src/hp34comm.h	Wed Oct 26 22:41:16 2016 +0200
+++ b/src/hp34comm.h	Sat Oct 29 23:44:31 2016 +0200
@@ -10,17 +10,13 @@
 #define MAX_BUFF 16
 #define BUF_SIZE 16
 
+
+
 class HPSerial {
 
 public:
-  enum TrState {
-        Idle = 0,
-        Tx,
-        Rx,
-    };
   typedef struct _CMD
   {
-    TrState direction;
     uint8_t cmd;
     uint8_t size;
     char value[MAX_BUFF+1];
@@ -29,7 +25,7 @@
 
 
   
-  HPSerial(PinName rx);
+  HPSerial(PinName tx, PinName rx);
   
   bool cmd_available(void);
   bool pop(CMD& cmd);
@@ -38,26 +34,57 @@
 		     
   
 private:
-  void reset(uint8_t errorno=0xFF);
-  void handleAck(uint8_t val);
-  void pushCmd(TrState direction, uint8_t cmd, uint8_t size, char *payload);
-  void handleChar(uint8_t val);
-  void setstatedbg(void);    
+  void pushCmd(uint8_t cmd, uint8_t size, char *payload);
   void rxIrq(void);
   void timeout(void);
 
  private:
-  RawSerial serial_rx;
+  RawSerial serial;
   uint8_t buf[BUF_SIZE];
   uint8_t head;
-  uint8_t tx_state;
-  uint8_t tx_cmd;
-  uint8_t tx_len;
-  bool tx_ack;
   CircularBuffer<CMD, 32> cmdbuf;
   unsigned long ncmd;
   unsigned int errs[MAX_ERRS];
   Ticker timeouter;
+
+  // state machine stuff
+  typedef enum {STATE_IDLE,
+		STATE_HANDCHEKED,
+		STATE_COMMAND,
+		STATE_PAYLOAD_SIZE,
+		STATE_PAYLOAD,
+		NUM_STATES} state_t;
+
+  
+  typedef struct instance_data {
+    uint8_t cmd;
+    uint8_t size;
+    uint8_t received;
+    char payload[MAX_BUFF];
+  } instance_data_t;
+
+  state_t do_state_initial(instance_data_t *data, uint8_t c);
+  state_t do_state_handcheck(instance_data_t *data, uint8_t c);
+  state_t do_state_command(instance_data_t *data, uint8_t c);
+  state_t do_state_payload_size(instance_data_t *data, uint8_t c);
+  state_t do_state_payload(instance_data_t *data, uint8_t c);
+
+  void send_ack(uint8_t c);
+  
+  // pointer to "state method" (ie. one of the just above)
+  typedef state_t(HPSerial::*statemethod)(instance_data_t *data, uint8_t c);
+  statemethod const state_table[NUM_STATES] = {
+      &HPSerial::do_state_initial,
+      &HPSerial::do_state_handcheck,
+      &HPSerial::do_state_command,
+      &HPSerial::do_state_payload_size,
+      &HPSerial::do_state_payload,
+  };
+  
+  state_t run_state(state_t cur_state, instance_data_t *data, uint8_t c);
+
+  state_t cur_state;
+  instance_data rx_data;
 };
 
 #endif