Add configurable boot grace time

This guards against the case when the RX takes longer to obtain a valid
link than the gyro takes to calibrate (previously this delay is all that
stopped immediate arming).

src/main/fc/config.c

@@ -134,6 +134,7 @@ PG_RESET_TEMPLATE(systemConfig_t, systemConfig,
     .debug_mode = DEBUG_MODE,
     .task_statistics = true,
     .cpu_overclock = false,
+    .powerOnArmingGraceTime = 5,
     .boardIdentifier = TARGET_BOARD_IDENTIFIER
 );
 #else

src/main/fc/config.h

@@ -72,6 +72,7 @@ typedef struct systemConfig_s {
 #if defined(STM32F4) && !defined(DISABLE_OVERCLOCK)
     uint8_t cpu_overclock;
 #endif
+    uint8_t powerOnArmingGraceTime; // in seconds
     char boardIdentifier[sizeof(TARGET_BOARD_IDENTIFIER) + 1];
 } systemConfig_t;
 #endif

src/main/fc/fc_core.c

@@ -152,6 +152,12 @@ void updateArmingStatus(void)
     if (ARMING_FLAG(ARMED)) {
         LED0_ON;
     } else {
+        // Check if the power on arming grace time has elapsed
+        if ((getArmingDisableFlags() & ARMING_DISABLED_BOOT_GRACE_TIME) && (millis() >= systemConfig()->powerOnArmingGraceTime * 1000)) {
+            // If so, unset the grace time arming disable flag
+            unsetArmingDisabled(ARMING_DISABLED_BOOT_GRACE_TIME);
+        }
+
         if (IS_RC_MODE_ACTIVE(BOXFAILSAFE)) {
             setArmingDisabled(ARMING_DISABLED_BOXFAILSAFE);
         } else {

src/main/fc/fc_init.c

@@ -719,6 +719,8 @@ void init(void)
     latchActiveFeatures();
     pwmEnableMotors();
 
+    setArmingDisabled(ARMING_DISABLED_BOOT_GRACE_TIME);
+
 #ifdef USE_OSD_SLAVE
     osdSlaveTasksInit();
 #else

src/main/fc/runtime_config.c

@@ -32,8 +32,8 @@ static uint32_t enabledSensors = 0;
 #if defined(OSD) || !defined(MINIMAL_CLI)
 const char *armingDisableFlagNames[]= {
     "NOGYRO", "FAILSAFE", "RX LOSS", "BOXFAILSAFE", "THROTTLE",
-    "ANGLE", "NO PREARM", "ARM SWITCH", "LOAD", "CALIB", "CLI",
+    "ANGLE", "BOOT GRACE", "NO PREARM", "ARM SWITCH", "LOAD",
-    "CMS", "OSD", "BST"
+    "CALIB", "CLI", "CMS", "OSD", "BST"
 };
 #endif
 

src/main/fc/runtime_config.h

@@ -41,17 +41,18 @@ typedef enum {
     ARMING_DISABLED_BOXFAILSAFE     = (1 << 3),
     ARMING_DISABLED_THROTTLE        = (1 << 4),
     ARMING_DISABLED_ANGLE           = (1 << 5),
-    ARMING_DISABLED_NOPREARM    = (1 << 6),
+    ARMING_DISABLED_BOOT_GRACE_TIME = (1 << 6),
-    ARMING_DISABLED_ARM_SWITCH  = (1 << 7),
+    ARMING_DISABLED_NOPREARM        = (1 << 7),
-    ARMING_DISABLED_LOAD        = (1 << 8),
+    ARMING_DISABLED_ARM_SWITCH      = (1 << 8),
-    ARMING_DISABLED_CALIBRATING = (1 << 9),
+    ARMING_DISABLED_LOAD            = (1 << 9),
-    ARMING_DISABLED_CLI         = (1 << 10),
+    ARMING_DISABLED_CALIBRATING     = (1 << 10),
-    ARMING_DISABLED_CMS_MENU    = (1 << 11),
+    ARMING_DISABLED_CLI             = (1 << 11),
-    ARMING_DISABLED_OSD_MENU    = (1 << 12),
+    ARMING_DISABLED_CMS_MENU        = (1 << 12),
-    ARMING_DISABLED_BST         = (1 << 13)
+    ARMING_DISABLED_OSD_MENU        = (1 << 13),
+    ARMING_DISABLED_BST             = (1 << 14)
 } armingDisableFlags_e;
 
-#define NUM_ARMING_DISABLE_FLAGS 14
+#define NUM_ARMING_DISABLE_FLAGS 15
 
 #if defined(OSD) || !defined(MINIMAL_CLI)
 extern const char *armingDisableFlagNames[NUM_ARMING_DISABLE_FLAGS];

src/main/fc/settings.c

@@ -704,6 +704,7 @@ const clivalue_t valueTable[] = {
 #if defined(STM32F4) && !defined(DISABLE_OVERCLOCK)
     { "cpu_overclock",              VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_OFF_ON }, PG_SYSTEM_CONFIG, offsetof(systemConfig_t, cpu_overclock) },
 #endif
+    { "pwr_on_arm_grace",           VAR_UINT8  | MASTER_VALUE, .config.minmax = { 0, 30 }, PG_SYSTEM_CONFIG, offsetof(systemConfig_t, powerOnArmingGraceTime) },
 
 // PG_VTX_CONFIG
 #ifdef VTX_RTC6705

src/test/unit/arming_prevention_unittest.cc

@@ -70,7 +70,7 @@ bool gyroCalibDone = false;
 
 #include "gtest/gtest.h"
 
-TEST(ArmingPreventionTest, CalibrationAngleThrottleArmSwitch)
+TEST(ArmingPreventionTest, CalibrationPowerOnGraceAngleThrottleArmSwitch)
 {
     // given
     simulationTime = 0;
@@ -91,13 +91,17 @@ TEST(ArmingPreventionTest, CalibrationAngleThrottleArmSwitch)
     rcData[THROTTLE] = 1400;
     rcData[4] = 1800;
 
+    // and
+    systemConfigMutable()->powerOnArmingGraceTime = 5;
+    setArmingDisabled(ARMING_DISABLED_BOOT_GRACE_TIME);
+
     // when
     updateActivatedModes();
     updateArmingStatus();
 
     // expect
     EXPECT_TRUE(isArmingDisabled());
-    EXPECT_EQ(ARMING_DISABLED_CALIBRATING | ARMING_DISABLED_ANGLE | ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
+    EXPECT_EQ(ARMING_DISABLED_BOOT_GRACE_TIME | ARMING_DISABLED_CALIBRATING | ARMING_DISABLED_ANGLE | ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
 
     // given
     // gyro calibration is done
@@ -109,7 +113,7 @@ TEST(ArmingPreventionTest, CalibrationAngleThrottleArmSwitch)
 
     // expect
     EXPECT_TRUE(isArmingDisabled());
-    EXPECT_EQ(ARMING_DISABLED_ANGLE | ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
+    EXPECT_EQ(ARMING_DISABLED_BOOT_GRACE_TIME | ARMING_DISABLED_ANGLE | ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
 
     // given
     // quad is level
@@ -120,7 +124,7 @@ TEST(ArmingPreventionTest, CalibrationAngleThrottleArmSwitch)
 
     // expect
     EXPECT_TRUE(isArmingDisabled());
-    EXPECT_EQ(ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
+    EXPECT_EQ(ARMING_DISABLED_BOOT_GRACE_TIME | ARMING_DISABLED_ARM_SWITCH | ARMING_DISABLED_THROTTLE, getArmingDisableFlags());
 
     // given
     rcData[THROTTLE] = 1000;
@@ -128,6 +132,17 @@ TEST(ArmingPreventionTest, CalibrationAngleThrottleArmSwitch)
     // when
     updateArmingStatus();
 
+    // expect
+    EXPECT_TRUE(isArmingDisabled());
+    EXPECT_EQ(ARMING_DISABLED_BOOT_GRACE_TIME | ARMING_DISABLED_ARM_SWITCH, getArmingDisableFlags());
+
+    // given
+    // arming grace time has elapsed
+    simulationTime += systemConfig()->powerOnArmingGraceTime * 1e6;
+
+    // when
+    updateArmingStatus();
+
     // expect
     EXPECT_TRUE(isArmingDisabled());
     EXPECT_EQ(ARMING_DISABLED_ARM_SWITCH, getArmingDisableFlags());
@@ -220,7 +235,6 @@ TEST(ArmingPreventionTest, ArmingGuardRadioLeftOnAndArmed)
     EXPECT_FALSE(isArmingDisabled());
 }
 
-
 TEST(ArmingPreventionTest, Prearm)
 {
     // given