diff -r c850674a3101 -r b3c3d54d2c7c src/hp34comm.h
--- a/src/hp34comm.h	Sun Nov 01 22:16:33 2020 +0100
+++ b/src/hp34comm.h	Sun Nov 01 22:21:19 2020 +0100
@@ -32,22 +32,24 @@
 
   void startup(uint8_t keycode=0xFF);
   void sendkey(uint8_t keycode);
+  void send_key_when_idle();
 
 private:
   void pushCmd(uint8_t cmd, uint8_t size, char *payload);
-  void rxIrq(void);
+  void rx_irq(void);
   void timeout(void);
   void set_timer(Kernel::Clock::duration_u32 v=0ms) {
     timeouter.detach();
     if (v > 0ms)
       timeouter.attach(callback(this, &HPSerial::timeout), v);
-  }
+  };
 
  private:
   UnbufferedSerial serial;
   uint8_t buf[BUF_SIZE];
   uint8_t head;
   CircularBuffer<CMD, 32> cmdbuf;
+  CircularBuffer<uint8_t, 32> sendbuf;
   unsigned long ncmd;
   unsigned int errs[MAX_ERRS];
   Ticker timeouter;
@@ -84,7 +86,6 @@
     STATE_PAYLOAD_SIZE,
     STATE_PAYLOAD,
     STATE_SENDING,
-    STATE_EOT,
     NUM_STATES} state_t;
   state_t state() {return cur_state;};
 
@@ -102,7 +103,6 @@
   state_t do_state_payload_size(uint8_t c);
   state_t do_state_payload(uint8_t c);
   state_t do_state_sending(uint8_t c=0x00);
-  state_t do_state_eot(uint8_t c=0x55);
 
   void send_ack(uint8_t c);