diff --git a/Multiprotocol/ESky_nrf24l01.ino b/Multiprotocol/ESky_nrf24l01.ino
index 1ed7d3d..9281697 100644
--- a/Multiprotocol/ESky_nrf24l01.ino
+++ b/Multiprotocol/ESky_nrf24l01.ino
@@ -117,11 +117,10 @@ static void __attribute__((unused)) ESKY_send_packet(uint8_t bind)
 		// For arithmetic simplicity, channels are repeated in rf_channels array
 		if (hopping_frequency_no == 0)
 		{
-			const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2};
 			for (uint8_t i = 0; i < 6; i++)
 			{
-				packet[i*2]   = Servo_data[ch[i]]>>8;	//high byte of servo timing(1000-2000us)
-				packet[i*2+1] = Servo_data[ch[i]]&0xFF;	//low byte of servo timing(1000-2000us)
+				packet[i*2]   = Servo_data[CH_AETR[i]]>>8;	//high byte of servo timing(1000-2000us)
+				packet[i*2+1] = Servo_data[CH_AETR[i]]&0xFF;	//low byte of servo timing(1000-2000us)
 			}
 		}
 		rf_ch = hopping_frequency[hopping_frequency_no];
diff --git a/Multiprotocol/FlySky_a7105.ino b/Multiprotocol/FlySky_a7105.ino
index 4810b5d..92f723d 100644
--- a/Multiprotocol/FlySky_a7105.ino
+++ b/Multiprotocol/FlySky_a7105.ino
@@ -142,11 +142,10 @@ static void __attribute__((unused)) flysky_build_packet(uint8_t init)
     packet[2] = rx_tx_addr[2];
     packet[3] = rx_tx_addr[1];
     packet[4] = rx_tx_addr[0];
-	const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2, AUX3, AUX4};
 	for(i = 0; i < 8; i++)
 	{
-		packet[5 + i*2]=Servo_data[ch[i]]&0xFF;		//low byte of servo timing(1000-2000us)
-		packet[6 + i*2]=(Servo_data[ch[i]]>>8)&0xFF;	//high byte of servo timing(1000-2000us)
+		packet[5 + i*2]=Servo_data[CH_AETR[i]]&0xFF;		//low byte of servo timing(1000-2000us)
+		packet[6 + i*2]=(Servo_data[CH_AETR[i]]>>8)&0xFF;	//high byte of servo timing(1000-2000us)
 	}
     flysky_apply_extension_flags();
 }
diff --git a/Multiprotocol/Hisky_nrf24l01.ino b/Multiprotocol/Hisky_nrf24l01.ino
index c6edabe..36c35b8 100644
--- a/Multiprotocol/Hisky_nrf24l01.ino
+++ b/Multiprotocol/Hisky_nrf24l01.ino
@@ -120,9 +120,8 @@ static void __attribute__((unused)) build_ch_data()
 {
 	uint16_t temp;
 	uint8_t i,j;
-	const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2, AUX3, AUX4};
 	for (i = 0; i< 8; i++) {
-		j=ch[i];
+		j=CH_AETR[i];
 		temp=map(limit_channel_100(j),PPM_MIN_100,PPM_MAX_100,0,1000);            			
 		if (j == THROTTLE) // It is clear that hisky's throttle stick is made reversely, so I adjust it here on purpose
 			temp = 1000 -temp;
diff --git a/Multiprotocol/J6Pro_cyrf6936.ino b/Multiprotocol/J6Pro_cyrf6936.ino
index e434460..f82bb70 100644
--- a/Multiprotocol/J6Pro_cyrf6936.ino
+++ b/Multiprotocol/J6Pro_cyrf6936.ino
@@ -78,11 +78,10 @@ static void __attribute__((unused)) j6pro_build_data_packet()
     uint8_t i;
     uint32_t upperbits = 0;
 	uint16_t value;
-	const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2, AUX3, AUX4, AUX5, AUX6, AUX7, AUX8};
     packet[0] = 0xaa; //FIXME what is this?
     for (i = 0; i < 12; i++)
 	{
-        value = convert_channel_10b(ch[i]);
+        value = convert_channel_10b(CH_AETR[i]);
         packet[i+1] = value & 0xff;
         upperbits |= (value >> 8) << (i * 2);
     }
diff --git a/Multiprotocol/Multiprotocol.ino b/Multiprotocol/Multiprotocol.ino
index 2e1cd67..820e11c 100644
--- a/Multiprotocol/Multiprotocol.ino
+++ b/Multiprotocol/Multiprotocol.ino
@@ -74,6 +74,11 @@ uint8_t  RX_num;
 uint8_t calData[48][3];
 #endif
 
+//Channel mapping for protocols
+const uint8_t CH_AETR[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2, AUX3, AUX4, AUX5, AUX6, AUX7, AUX8};
+//const uint8_t CH_TAER[]={THROTTLE, AILERON, ELEVATOR, RUDDER, AUX1, AUX2, AUX3, AUX4, AUX5, AUX6, AUX7, AUX8};
+//const uint8_t CH_RETA[]={RUDDER, ELEVATOR, THROTTLE, AILERON, AUX1, AUX2, AUX3, AUX4, AUX5, AUX6, AUX7, AUX8};
+
 // Mode_select variables
 uint8_t mode_select;
 uint8_t protocol_flags=0,protocol_flags2=0;
@@ -650,6 +655,17 @@ static void module_reset()
 	}
 }
 
+int16_t map( int16_t x, int16_t in_min, int16_t in_max, int16_t out_min, int16_t out_max)
+{
+//  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+	long y ;
+	x -= in_min ;
+	y = out_max - out_min ;
+	y *= x ;
+	x = y / (in_max - in_min) ;
+	return x  + out_min ;
+}
+
 // Channel value is converted to 8bit values full scale
 uint8_t convert_channel_8b(uint8_t num)
 {
diff --git a/Multiprotocol/SFHSS_cc2500.ino b/Multiprotocol/SFHSS_cc2500.ino
index 4a8b545..29f1880 100644
--- a/Multiprotocol/SFHSS_cc2500.ino
+++ b/Multiprotocol/SFHSS_cc2500.ino
@@ -135,12 +135,10 @@ static void __attribute__((unused)) SFHSS_build_data_packet()
 #define spacer1 0x02 //0b10
 #define spacer2 (spacer1 << 4)
     uint8_t ch_offset = state == SFHSS_DATA1 ? 0 : 4;
-	const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER, AUX1, AUX2, AUX3, AUX4};
-
-    uint16_t ch1 = SFHSS_convert_channel(ch[ch_offset+0]);
-    uint16_t ch2 = SFHSS_convert_channel(ch[ch_offset+1]);
-    uint16_t ch3 = SFHSS_convert_channel(ch[ch_offset+2]);
-    uint16_t ch4 = SFHSS_convert_channel(ch[ch_offset+3]);
+    uint16_t ch1 = SFHSS_convert_channel(CH_AETR[ch_offset+0]);
+    uint16_t ch2 = SFHSS_convert_channel(CH_AETR[ch_offset+1]);
+    uint16_t ch3 = SFHSS_convert_channel(CH_AETR[ch_offset+2]);
+    uint16_t ch4 = SFHSS_convert_channel(CH_AETR[ch_offset+3]);
     
     packet[0]  = 0x81; // can be 80, 81, 81 for Orange, only 81 for XK
     packet[1]  = rx_tx_addr[0];
diff --git a/Multiprotocol/SLT_nrf24l01.ino b/Multiprotocol/SLT_nrf24l01.ino
index e97ae54..0622b55 100644
--- a/Multiprotocol/SLT_nrf24l01.ino
+++ b/Multiprotocol/SLT_nrf24l01.ino
@@ -111,9 +111,8 @@ static void __attribute__((unused)) SLT_build_packet()
 {
 	// aileron, elevator, throttle, rudder, gear, pitch
 	uint8_t e = 0; // byte where extension 2 bits for every 10-bit channel are packed
-	const uint8_t ch[]={AILERON, ELEVATOR, THROTTLE, RUDDER};
 	for (uint8_t i = 0; i < 4; ++i) {
-		uint16_t v = convert_channel_10b(ch[i]);
+		uint16_t v = convert_channel_10b(CH_AETR[i]);
 		packet[i] = v;
 		e = (e >> 2) | (uint8_t) ((v >> 2) & 0xC0);
 	}