diff --git a/module/cores/arduino/port_sam/core_digital.c b/module/cores/arduino/port_sam/core_digital.c
index 0b931ee..771e618 100644
--- a/module/cores/arduino/port_sam/core_digital.c
+++ b/module/cores/arduino/port_sam/core_digital.c
@@ -32,9 +32,9 @@ void pinMode( uint32_t ulPin, PinMode ulMode )
 
   if ( (ulMode == INPUT) || (ulMode == INPUT_PULLUP) || (ulMode == INPUT_PULLDOWN) )
   {
-    /* if all pins are OUTPUT, enable PIO Controller clocking */
-    if ( Ports[g_aPinMap[ulPin].iPort].pGPIO->PIO_OSR == 0xffffffff )
-    {
+      /* check if PIO is already clocked */
+      if (!(PMC->PMC_PCSR0 & (1 << Ports[g_aPinMap[ulPin].iPort].ulId)))
+      {
 //      if (Ports[g_aPinMap[ulPin].iPort].ulId < 32)
       {
         PMC->PMC_PCER0 = 1 << Ports[g_aPinMap[ulPin].iPort].ulId;