diff --git a/flipcontrol_esp32/src/main.cpp b/flipcontrol_esp32/src/main.cpp
index 198f708..64eaa97 100644
--- a/flipcontrol_esp32/src/main.cpp
+++ b/flipcontrol_esp32/src/main.cpp
@@ -37,9 +37,12 @@ void selectColumnClear(uint8_t selcolumn);
 void selectColumnSet(uint8_t selcolumn);
 void selectColumn(uint8_t selcolumn, bool clear);
 
+bool HBridgeOK();
+void shiftData();
+
 unsigned long loopmillis=0;
 unsigned long last_update=0;
-#define UPDATE_INTERVAL 3000
+#define UPDATE_INTERVAL 500
 
 
 void setup() {
@@ -83,7 +86,26 @@ void loop() {
     digitalWrite(PIN_OE, LOW); //Active Low
 
 
-    
+    static bool init=false;
+    if (!init) {
+        delay(2000);
+        Serial.println("Clearing Display");
+        for (int l=0;l<25;l++) {
+            selectColumnClear(l%25);
+
+            shiftData();
+
+            if (!clearSelectedColumn()) {
+                Serial.println("Error clearing column!");
+            }else{
+                Serial.println("Cleared");
+            }
+
+            delay(50);
+        }
+        init=true;
+        delay(1000);
+    }
     
 
     if (loopmillis > last_update + UPDATE_INTERVAL) 
@@ -126,11 +148,11 @@ void loop() {
         //reset pin on annax board input should be used (not pulled to gnd for a short time) after dots have been flipped (to disable potentially activated transistors)
 
 
-        selectColumnClear(countz%25);
+        //selectColumnClear(countz%25);
 
-        //selectColumnSet(countz%25);
+        selectColumnSet((12+(countz/25))%25); //lower column number is on the left
 
-        //row=pow(2, countz/25);
+        row=pow(2, countz%16); //low significant bits are lower rows (when connector at top)
 
         
 
@@ -143,28 +165,18 @@ void loop() {
         Serial.println();
         //reset pin on ribbon cable high (12Vpullup/open), then low (via Transistor)
         
-        //Select Columns via Shift registers
-        for (uint8_t i=0;i<7;i++) {
-            shiftOutSlow(PIN_DATA_DRVBRD, PIN_CLK_DRVBRD, LSBFIRST, col[6-i]);
-        }
-        
-        //select Rows via shift registers on own controller board
-        shiftOutSlow(PIN_DATA, PIN_CLK, LSBFIRST, row%256); 
-        shiftOutSlow(PIN_DATA, PIN_CLK, LSBFIRST, row/256);  //LSBFIRST= LSB is QH, bit 8 is QA.
-        digitalWrite(PIN_LATCH, HIGH);
-        delayMicroseconds(100);
-        digitalWrite(PIN_LATCH, LOW);
+        shiftData();
 
 
-        //setSelectedDot();
+        setSelectedDot();
 
 
         
-        if (!clearSelectedColumn()) {
+        /*if (!clearSelectedColumn()) {
             Serial.println("Error clearing column!");
         }else{
             Serial.println("Cleared");
-        }
+        }*/
         
         
         
@@ -214,7 +226,17 @@ void selectColumn(uint8_t selcolumn, bool clear) {
         col[i]=0;
     }
 
-    col[sc_byte]=pow(2, (sc_bit*2+clear));
+    col[sc_byte]=pow(2, (sc_bit*2+clear)); // possible numbers for clear=false: 1,4,16,64
+    /*
+    if (!clear) { //when setting a dot set all other columns to 12v (to avoid ghost flipping)
+        for (uint8_t i=0;i<7;i++) {
+            col[i]+=2+8+32+128; //set to +12v
+        }
+        col[sc_byte]-=pow(2, (sc_bit*2+1)); //avoid short circuit on H-bridge
+    }
+    */
+    
+    
 }
 
 bool clearSelectedColumn() {
@@ -235,7 +257,7 @@ bool clearSelectedColumn() {
 
     digitalWrite(PIN_DRIVE, HIGH);
     digitalWrite(PIN_CLEAR, HIGH);
-    delay(200);
+    delay(50);
     digitalWrite(PIN_CLEAR, LOW);
     digitalWrite(PIN_DRIVE, LOW);
     return 1;
@@ -243,7 +265,7 @@ bool clearSelectedColumn() {
 
 bool setSelectedDot() {
     
-    for (uint8_t cc=0;cc<7;cc++) {
+    /*for (uint8_t cc=0;cc<7;cc++) {
         //Serial.print("checking cc="); Serial.println(cc);
         for (uint8_t i=1;i<8;i+=2) {
             if (CHECK_BIT(col[cc],i)) {
@@ -252,10 +274,42 @@ bool setSelectedDot() {
                 return 0; //a column is set to ground (should not be set for clear column)
             }
         }
+    }*/
+
+    if (!HBridgeOK) {
+        return 0;
     }
 
     digitalWrite(PIN_DRIVE, HIGH);
-    delay(200);
+    delay(10);
     digitalWrite(PIN_DRIVE, LOW);
     return 1;
+}
+
+bool HBridgeOK() {
+    for (uint8_t cc=0;cc<7;cc++) {
+        //Serial.print("checking cc="); Serial.println(cc);
+        for (uint8_t i=0;i<8;i+=2) {
+            if (CHECK_BIT(col[cc],i) && CHECK_BIT(col[cc],i+1)) {
+                Serial.print("Short circuit on bit ");
+                Serial.print(i); Serial.print(" col="); Serial.println(cc);
+                return 0; //a column is set to ground (should not be set for clear column)
+            }
+        }
+    }
+    return 1;
+}
+
+void shiftData() { //send out all data to shift registers
+    //Select Columns via Shift registers
+    for (uint8_t i=0;i<7;i++) {
+        shiftOutSlow(PIN_DATA_DRVBRD, PIN_CLK_DRVBRD, LSBFIRST, col[6-i]);
+    }
+    
+    //select Rows via shift registers on own controller board
+    shiftOutSlow(PIN_DATA, PIN_CLK, LSBFIRST, row%256); 
+    shiftOutSlow(PIN_DATA, PIN_CLK, LSBFIRST, row/256);  //LSBFIRST= LSB is QH, bit 8 is QA.
+    digitalWrite(PIN_LATCH, HIGH);
+    delayMicroseconds(100);
+    digitalWrite(PIN_LATCH, LOW);
 }
\ No newline at end of file