Add check for PWM being ENABLED

Author: henrygab

cores/nRF5/HardwarePWM.cpp

@@ -58,6 +58,7 @@ bool HardwarePWM::takeOwnership(uintptr_t token)
 {
   if (this->_owner_token       != 0) return false; // doesn't matter if it's actually a match ... it's not legal to take ownership twice
   if (this->usedChannelCount() != 0) return false; // at least one channel is already in use
+  if (this->enabled                ) return false; // if it's enabled, do not allow new ownership, even with no pins in use
   // use gcc built-in intrinsic to ensure atomicity
   // See https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html
   return __sync_bool_compare_and_swap(&(this->_owner_token), 0, token);
@@ -67,6 +68,7 @@ bool HardwarePWM::releaseOwnership(uintptr_t token)
 {
   if (!this->isOwner(token)         ) return false; // don't even look at peripheral
   if ( this->usedChannelCount() != 0) return false; // fail if any channels still have pins
+  if ( this->enabled                ) return false; // if it's enabled, do not allow ownership to be released, even with no pins in use
   // use gcc built-in intrinsic to ensure atomicity
   // See https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html
   return __sync_bool_compare_and_swap(&(this->_owner_token), token, 0);

libraries/Servo/src/nrf52/Servo.cpp

@@ -108,7 +108,10 @@ void Servo::detach()
   HardwarePWM * pwm = this->pwm;
   this->pwm = nullptr;
   pwm->removePin(pin);
-  pwm->releaseOwnership(_servoToken); // ignore failure ... which happens if a pin is still in use, for example
+  if (pwm->usedChannelCount() == 0) {
+    pwm->stop(); // disables peripheral so can release ownership
+    pwm->releaseOwnership(_servoToken);
+  }
 }
 
 void Servo::write(int value)