diff --git a/MonomeFTDI.cpp b/MonomeFTDI.cpp
diff --git a/MonomeFTDI.h b/MonomeFTDI.h
@@ -50,8 +50,8 @@
 
 ////////////
 /// dbg
-//#define PRINT_DBG(x) Serial.print((x))
-#define PRINT_DBG(x)
+#define PRINT_DBG(x) Serial.print((x))
+//#define PRINT_DBG(x)
 ///////////
 
 
@@ -64,6 +64,7 @@
 // Only single port chips are currently supported by the library,
 // so only three endpoints are allocated.
 #define FTDI_MAX_ENDPOINTS	3
+#define MAX_ENDPOINTS  3
 
 /// maximum unpacked size of led buffer,
 /// all frames/elements, 1 byte per led.
@@ -153,15 +154,15 @@ class MonomeFtdi : public USBDeviceConfig, public UsbConfigXtracter
   // receive buffer
   uint8_t rxBuf[MONOME_RX_BUF_LEN];
   // receive byte count
-  uint32_t rxBytes;
+  uint16_t rxBytes;
 
  public:
   MonomeFtdi(USBHost &usb, MonomeReportParser *con);
 
   // Basic IO 
   //  uint32_t read(uint32_t *nreadbytes, uint8_t *dataptr);
   // always use internal RX butter
-  uint32_t read(void);
+  uint16_t read(void);
   // always use external TX buffer
   uint32_t write(uint32_t datalen, uint8_t *dataptr);
 
@@ -172,7 +173,7 @@ class MonomeFtdi : public USBDeviceConfig, public UsbConfigXtracter
   void setPollPeriod(uint32_t period) { pollPeriod = period; }
 
   // getters for rx count / data
-  uint32_t rx_bytes(void) { return rxBytes > 1 ? rxBytes - 2 : 0; }
+  uint16_t rx_bytes(void) { return rxBytes > 1 ? rxBytes - 2 : 0; }
   uint8_t* rx_buf(void) { return rxBuf + 2; }
 
   // string descriptor utility

diff --git a/MonomeHost.ino b/MonomeHost.ino
@@ -4,45 +4,61 @@
 USBHost usb;
 MonomeController monome(usb);
 
+#if (USB_VID==0x2341 && defined(ARDUINO_SAMD_ZERO)) || (USB_VID==0x2a03 && defined(ARDUINO_SAM_ZERO))
+#define SerialDebug SERIAL_PORT_MONITOR
+#else
+#define SerialDebug Serial1
+#endif
+
 void GridKeyCallback(byte x, byte y, byte z) { 
-  Serial.print("grid key: ");
-  Serial.print(x);
-  Serial.print(" , ");
-  Serial.print(y);
-  Serial.print(" , ");
-  Serial.print(z);
-  Serial.print("\r\n");
+  SerialDebug.print("grid key: ");
+  SerialDebug.print(x);
+  SerialDebug.print(" , ");
+  SerialDebug.print(y);
+  SerialDebug.print(" , ");
+  SerialDebug.print(z);
+  SerialDebug.print("\r\n");
 
-  monome.led_clear();
-  monome.led_set(x, y, 15);
-  monome.refresh();
+  if (z == 1) {
+    monome.led_set(x, y, 1);
+    monome.refresh();
+  }
 }
 
 void ConnectCallback(const char * name, byte cols, byte rows) {
-  Serial.print("\r\nmonome device connected; type: ");
-  Serial.print(name);
-  Serial.print(" ; columns: ");
-  Serial.print(cols);
-  Serial.print(" ; rows: ");
-  Serial.print(rows);
-  Serial.print("\r\n");
+  SerialDebug.print("\r\nmonome device connected; type: ");
+  SerialDebug.print(name);
+  SerialDebug.print(" ; columns: ");
+  SerialDebug.print(cols);
+  SerialDebug.print(" ; rows: ");
+  SerialDebug.print(rows);
+  SerialDebug.print("\r\n");
+
+  monome.led_set(1, 1, 15);
+  monome.led_set(1, 3, 10);
+  monome.led_set(1, 5, 5);
+
+  monome.refresh();
 }
 
+void setup() {
+  SerialDebug.begin(9600);
 
-void setup() { 
+  SerialDebug.print("\n\nStarting...\n");
+  delay(200);
 
   // set connection callback
   monome.SetConnectCallback(&ConnectCallback);
   // set key event callback
   monome.SetGridKeyCallback(&GridKeyCallback);
+  SerialDebug.print("\n\nConnect set...\n");
 
-  Serial.begin(115200);
-  Serial.print("\n\nStarting...\n");
   delay(200);
+
 }
 
-void loop() { 
+void loop() {
   usb.Task();
   /// alternatively, refresh on every tick:
-  //  monome.refresh();
+//    monome.refresh();
 }