More reliable typing via synchronization to host clock

terminal_keyboard_emulator.ino

@@ -12,8 +12,8 @@ const int dataPin = 3; // in, kbd data
 const int outPin = 4; // out, kbd led
 
 // constant config
-const int slaveClockDivider = 4;
-const int timerDelay = 528 / slaveClockDivider;
+const int slaveClockDivider = 8;
+const int timerDelay = 530 / slaveClockDivider;
 
 // variables
 volatile int slaveClockStep = 0;
@@ -45,7 +45,7 @@ volatile byte nextKey = 0;
 void typeKey(byte key) {
     nextKey = key;
     nextKeyReady = true;
-    Serial.print("Typing key "); Serial.println((int) key);
+    //Serial.print("Typing key "); Serial.println((int) key);
 }
     
 void sendKey(byte key) { 
@@ -54,9 +54,7 @@ void sendKey(byte key) {
     dataDelay = 0;
     packetDelay = 0;
     packetTail = 15;
-    Serial.print("Sending key "); Serial.println((int) key);
-    //Timer1.initialize(timerDelay);
-    //Timer1.start();
+    //Serial.print("Sending key "); Serial.println((int) key);
 }
 
 void onHostStatusChange() {
@@ -65,8 +63,9 @@ void onHostStatusChange() {
   lastChange = timeNow;
   if (changeDiff >= 10 && nextKeyReady) {
       nextKeyReady = false;
-      Serial.println("Status change with key");
       sendKey(nextKey);
+      Timer1.start(); // synchronize with the host
+      slaveClockStep = 0;
   }
 }
 
@@ -86,7 +85,6 @@ void onHostClockCycle(void)
     packetTail--;
     dataBit = LOW;
   } else {
-    //Timer1.stop();
   }
   digitalWrite(pinData, dataBit);
 }
@@ -145,10 +143,11 @@ void setupKeyMapping() {
 }
 
 char translateKeyToChar(int key) {
+  return key; //m[key];
   if (sizeof(m) <= key) {
     return 0;
   }
-  return key; //m[key];
+  return m[key];
 }
 
 void printChar(char keyChar) {
@@ -183,10 +182,10 @@ void onTimerInterrupt()
 {
   onSlaveClockInterrupt();
 
-  slaveClockStep = (slaveClockStep + 1) % slaveClockDivider;
   if (slaveClockStep == 0) {
       onHostClockCycle();
   }
+  slaveClockStep = (slaveClockStep + 1) % slaveClockDivider;
 }
 
 // ----
@@ -211,7 +210,6 @@ void setup(void)
   
   Timer1.initialize(timerDelay);
   Timer1.attachInterrupt(onTimerInterrupt);
-  //Timer1.stop();
 
   Serial.println("Keyboard ready");
 }
@@ -225,11 +223,19 @@ void loop(void)
 	typeKey(key);
       }
   }
+  /**/
+  
   // type key from keyboard
   if (counter >= numbits) {
     processKbdByte(data);
     data = B0;
     counter = 0;
   }
+  /**/
+
+  /*/ auto-type test
+  delay(500);
+  typeKey('B');
+  /**/
 }