diff --git a/arduino/arduino.ino b/arduino/arduino.ino
index 84841a7..ed2f069 100644
--- a/arduino/arduino.ino
+++ b/arduino/arduino.ino
@@ -95,6 +95,9 @@ void write() {
     /*     Serial.print(","); */
     /* } */
     /* Serial.println("."); */
+    // transfer the size in LE
+    SPI.transfer(static_cast<uint8_t>(size));
+    SPI.transfer(static_cast<uint8_t>(size >> 8));
 
     SPI.transfer(buffer, size);
     Serial.write(ControlBytes::WRITE);
@@ -154,6 +157,14 @@ void loop() {
             break;
         }
         case ControlBytes::WRITE: {
+            digitalWrite(LEDG, LOW);
+            digitalWrite(LEDR, HIGH);
+            read();
+            digitalWrite(LEDR, LOW);
+            digitalWrite(LEDG, HIGH);
+            break;
+        }
+        case ControlBytes::READ: {
             digitalWrite(LEDG, LOW);
             digitalWrite(LEDR, HIGH);
             write();