SymaX impove rates in headless mode.

Multiprotocol/Symax_nrf24l01.ino

@@ -30,6 +30,7 @@
 #define SYMAX_FLAG_VIDEO			0x02
 #define SYMAX_FLAG_PICTURE			0x04
 #define SYMAX_FLAG_HEADLESS			0x08
+#define SYMAX_XTRM_RATES			0x10
 
 #define SYMAX_PAYLOADSIZE			10		// receive data pipes set to this size, but unused
 #define SYMAX_MAX_PACKET_LENGTH		16		// X11,X12,X5C-1 10-byte, X5C 16-byte
@@ -58,6 +59,7 @@ static void __attribute__((unused)) SYMAX_read_controls()
 {
 	// Protocol is registered AETRF, that is
 	// Aileron is channel 1, Elevator - 2, Throttle - 3, Rudder - 4, Flip control - 5
+	// Extended (trim-added) Rates - 6, Photo - 7, Video - 8, Headless - 9
 	aileron  = convert_channel_s8b(AILERON);
 	elevator = convert_channel_s8b(ELEVATOR);
 	throttle = convert_channel_8b(THROTTLE);
@@ -67,6 +69,9 @@ static void __attribute__((unused)) SYMAX_read_controls()
 	// Channel 5
 	if (Servo_AUX1)
 		flags = SYMAX_FLAG_FLIP;
+	// Channel 6
+	if (Servo_AUX2)
+		flags |= SYMAX_XTRM_RATES;
 	// Channel 7
 	if (Servo_AUX3)
 		flags |= SYMAX_FLAG_PICTURE;
@@ -76,6 +81,7 @@ static void __attribute__((unused)) SYMAX_read_controls()
 	// Channel 9
 	if (Servo_AUX5)
 		flags |= SYMAX_FLAG_HEADLESS;
+	    flags &= ~SYMAX_XTRM_RATES;	// Extended rates & headless incompatible
 }
 
 #define X5C_CHAN2TRIM(X) ((((X) & 0x80 ? 0xff - (X) : 0x80 + (X)) >> 2) + 0x20)
@@ -98,9 +104,15 @@ static void __attribute__((unused)) SYMAX_build_packet_x5c(uint8_t bind)
 		packet[1] = rudder;
 		packet[2] = elevator ^ 0x80;  // reversed from default
 		packet[3] = aileron;
-		packet[4] = X5C_CHAN2TRIM(rudder ^ 0x80);// drive trims for extra control range
+		if (flags & SYMAX_XTRM_RATES) {	// drive trims for extra control range
-		packet[5] = X5C_CHAN2TRIM(elevator);
+			packet[4] = X5C_CHAN2TRIM(rudder ^ 0x80);
-		packet[6] = X5C_CHAN2TRIM(aileron ^ 0x80);
+			packet[5] = X5C_CHAN2TRIM(elevator);
+			packet[6] = X5C_CHAN2TRIM(aileron ^ 0x80);
+		} else {
+			packet[4] = 0x00;
+			packet[5] = 0x00;
+			packet[6] = 0x00;
+		}
 		packet[7] = 0xae;
 		packet[8] = 0xa9;
 		packet[9] = 0x00;
@@ -138,9 +150,14 @@ static void __attribute__((unused)) SYMAX_build_packet(uint8_t bind)
 		packet[2] = rudder;
 		packet[3] = aileron;
 		packet[4] = (flags & SYMAX_FLAG_VIDEO   ? 0x80 : 0x00) | (flags & SYMAX_FLAG_PICTURE ? 0x40 : 0x00);
-		packet[5] = (elevator >> 2) | 0xc0; //always high rates (bit 7 is rate control)
+		packet[5] = 0xc0;	//always high rates (bit 7 is rate control)
-		packet[6] = (rudder >> 2)  | (flags & SYMAX_FLAG_FLIP ? 0x40 : 0x00);
+		packet[6] = flags & SYMAX_FLAG_FLIP ? 0x40 : 0x00;
-		packet[7] = (aileron >> 2) | (flags & SYMAX_FLAG_HEADLESS ? 0x80 : 0x00);
+		packet[7] = flags & SYMAX_FLAG_HEADLESS ? 0x80 : 0x00;
+		if (flags & SYMAX_XTRM_RATES) {	    // use trims to extend controls
+			packet[5] |= elevator >> 2;
+			packet[6] |= rudder >> 2;
+			packet[7] |= aileron >> 2;
+		}
 		packet[8] = 0x00;
 	}
 	packet[9] = SYMAX_checksum(packet);

docs/Models.md

@@ -7,9 +7,9 @@ The Deviation project (on which this project was based) have a useful list of mo
 <img src="http://img2.cheapdrone.co.uk/images/upload/2014/12/X5C%203/SKU115108-7.jpg" Width="200" Height="200" />
 
 ## Channel Map
-CH1|CH2|CH3|CH4|CH5|CH6|CH7|CH8
+CH1|CH2|CH3|CH4|CH5|CH6|CH7|CH8|CH9
----|---|---|---|---|---|---|---
+---|---|---|---|---|---|---|---|---
-A|E|T|R|FLIP|RATES|PICTURE|VIDEO
+A|E|T|R|FLIP|RATES|PICTURE|VIDEO|HEADLESS
 
 ## Binding
 There are no special binding instructions.  The model powers up in Autobind mode and expects the bind sequence from the transmitter within the first 4-5 seconds. 
@@ -45,6 +45,25 @@ One of the most annoying functions on the Syma X5C is that the motors stop when
 1. When you want to fly in "idle-up" mode flick the switch and your stabilization will always be active.  
 1. Remeber to switch off idle-up as soon as the quad lands (or crashes - to avoid damage to the motors)
 
+### Additional notes on rates:
+
+The SymaX driver can add full trim to the control output.  Doing so enables
+dramatic rates, steep angles, and high speeds.  If CH6 is low, the usual Syma
+full rates will be in effect.  If CH6 is high, the SymaX extreme trim rates will be
+in effect.  Be cautious when first trying out the extreme rates.
+
+The extreme rates do not work with with headless mode because in this
+mode the trim and the primary control directions may not be aligned - the
+primary control directions will be based on the headless mode, but the trims
+remain based upon the quadcopter's heading.  So extreme rates are disabled
+when headless mode is selected.
+
+Be aware that the use of extreme rates and the resulting steep angles will
+disorient the gyro responsible for maintaining headless mode, and that the
+direction the quadcopter thinks you selected for headless mode may not be
+correct after especially wild flights.
+
+
 # Inductrix (Horizon Hobby)
 
 <img src="https://s7d5.scene7.com/is/image/horizonhobby/BLH8700_a0" Width="200" Height="200" />