check also return of FspTimer::get_available_timer()

Author: mast-eu

libraries/Arduino_LED_Matrix/src/Arduino_LED_Matrix.h

@@ -173,13 +173,15 @@ class ArduinoLEDMatrix
         bool rv = true;
         uint8_t type;
         uint8_t ch = FspTimer::get_available_timer(type);
-        // TODO: avoid passing "this" argument to remove autoscroll
-        rv &= _ledTimer.begin(TIMER_MODE_PERIODIC, type, ch, 10000.0, 50.0, turnOnLedISR, this);
-        rv &= _ledTimer.setup_overflow_irq();
-        rv &= _ledTimer.open();
-        rv &= _ledTimer.start();
-
-        return rv;
+        if(ch != -1) {
+            // TODO: avoid passing "this" argument to remove autoscroll
+            rv &= _ledTimer.begin(TIMER_MODE_PERIODIC, type, ch, 10000.0, 50.0, turnOnLedISR, this);
+            rv &= _ledTimer.setup_overflow_irq();
+            rv &= _ledTimer.open();
+            rv &= _ledTimer.start();
+            return rv;
+        }
+        return false;
     }
     void next() {
         uint32_t frame[3];