APM_RC: added a test for ISR masking in APM_RC

libraries/APM_RC/examples/ISR_Mask/ISR_Mask.pde

@@ -0,0 +1,63 @@
+/*
+  test interrupt masking methods on APM1
+ */
+
+#include <FastSerial.h>
+#include <AP_Common.h>
+#include <AP_Math.h>
+#include <Arduino_Mega_ISR_Registry.h>
+#include <APM_RC.h>
+
+FastSerialPort0(Serial);
+
+Arduino_Mega_ISR_Registry isr_registry;
+APM_RC_APM1 APM_RC;
+
+void setup()
+{
+    Serial.begin(115200);
+    isr_registry.init();
+    APM_RC.Init(&isr_registry);
+    Serial.println("Interrupt masking test");
+    delay(10);
+}
+
+static uint16_t last_values[8];
+
+#define USE_CLI  0
+#define USE_MASK 1
+
+void loop()
+{
+	if (APM_RC.GetState() == 1) {
+		bool changed = false;
+		for (uint8_t i = 0; i < 8; i++) {
+			uint16_t v = APM_RC.InputCh(i);
+			if (abs(v - last_values[i]) > 10) {
+				changed = true;
+			}
+			last_values[i] = v;
+		}
+		if (changed) {
+			for (uint8_t i = 0; i < 8; i++) {
+				Serial.printf("%u:%4u ", (unsigned)i, (unsigned)last_values[i]);
+			}
+			Serial.println();
+			delayMicroseconds(500);
+		}
+	}
+
+#if USE_CLI
+	uint8_t oldSREG = SREG;
+	cli();
+	delayMicroseconds(100);
+	SREG = oldSREG;
+#endif
+
+#if USE_MASK
+	uint8_t _timsk4 = TIMSK4;
+	TIMSK4 &= ~(1<<ICIE4);
+	delayMicroseconds(100);
+	TIMSK4 = _timsk4;
+#endif
+}

libraries/APM_RC/examples/ISR_Mask/Makefile

@@ -0,0 +1,2 @@
+BOARD	=	mega2560
+include ../../../AP_Common/Arduino.mk