RadioLink Surface protocol: initial commit

Lua_scripts/MultiChan.txt

@@ -136,6 +136,7 @@
 72,0,Q90C,Std,0,FMode,VTX+
 50,0,Redpine,Fast,0,sCH5,sCH6,sCH7,sCH8,sCH9,sCH10,sCH11,sCH12,sCH13,sCH14,sCH15,sCH16
 50,1,Redpine,Slow,0,sCH5,sCH6,sCH7,sCH8,sCH9,sCH10,sCH11,sCH12,sCH13,sCH14,sCH15,sCH16
+74,0,RadioLink,Surface,0,CH5,CH6,CH7,CH8,FS_CH1,FS_CH2,FS_CH3,FS_CH4,FS_CH5,FS_CH6,FS_CH7,FS_CH8
 21,0,SFHSS,Std,0,CH5,CH6,CH7,CH8
 19,0,Shenqi,Cycle,1
 68,0,Skyartec,Std,0,CH5,CH6,CH7

Lua_scripts/MultiChannelsUpdater.lua

@@ -278,6 +278,15 @@ local function Multi_Init()
     ch_order = math.floor(ch_order/4)
     channel_names[bitand(ch_order,3)+1] = stick_names[1]
   end
+ 
+  --Exceptions on first 4 channels...
+  if ( protocol == 74 and sub_protocol == 0 ) then -- RadioLink Surface
+    channel_names[1] = "ST"
+    channel_names[2] = "THR"
+    channel_names[3] = "CH3"
+    channel_names[4] = "CH4"
+  end
+ 
   --Check MultiChan.txt
   local f = io.open("/SCRIPTS/TOOLS/MultiChan.txt", "r")
   if f == nil then return end

Multiprotocol/Multi.txt

@@ -71,3 +71,4 @@
 71,JJRC345
 72,Q90C
 73,Kyosho
+74,RadioLink,Surface

Multiprotocol/Multi_Names.ino

@@ -87,6 +87,7 @@ const char STR_FRSKYR9[]	="FrSkyR9";
 const char STR_PROPEL[]		="Propel";
 const char STR_SKYARTEC[]	="Skyartc";
 const char STR_KYOSHO[]		="Kyosho";
+const char STR_RLINK[]		="RadLink";
 const char STR_TEST[]		="Test";
 const char STR_FAKE[]		="Fake";
 
@@ -140,6 +141,7 @@ const char STR_SUBTYPE_WFLY[] =       "\x06""WFR0xS";
 const char STR_SUBTYPE_HOTT[] =       "\x07""Sync\0  ""No_Sync";
 const char STR_SUBTYPE_PELIKAN[] =    "\x04""Pro\0""Lite";
 const char STR_SUBTYPE_V761[] =       "\x03""3CH""4CH";
+const char STR_SUBTYPE_RLINK[] =      "\x07""Surface";
 
 enum
 {
@@ -324,6 +326,9 @@ const mm_protocol_definition multi_protocols[] = {
 	#if defined(REDPINE_CC2500_INO)
 		{PROTO_REDPINE,    STR_REDPINE,   2, STR_SUBTYPE_REDPINE,   OPTION_RFTUNE  },
 	#endif
+	#if defined(RLINK_CC2500_INO)
+		{PROTO_RLINK,      STR_RLINK,     1, STR_SUBTYPE_RLINK,     OPTION_RFTUNE  },
+	#endif
 	#if defined(SCANNER_CC2500_INO)
 	//	{PROTO_SCANNER,    STR_SCANNER,   0, NO_SUBTYPE,            OPTION_NONE    },
 	#endif

Multiprotocol/Multiprotocol.h

@@ -19,7 +19,7 @@
 #define VERSION_MAJOR		1
 #define VERSION_MINOR		3
 #define VERSION_REVISION	1
-#define VERSION_PATCH_LEVEL	42
+#define VERSION_PATCH_LEVEL	43
 
 //******************
 // Protocols
@@ -100,6 +100,7 @@ enum PROTOCOLS
 	PROTO_JJRC345	= 71,	// =>NRF24L01
 	PROTO_Q90C		= 72,	// =>NRF24L01 or CC2500
 	PROTO_KYOSHO	= 73,	// =>A7105
+	PROTO_RLINK		= 74,	// =>CC2500
 
 	PROTO_FAKE		= 126,	// =>CC2500+NRF24L01
 	PROTO_TEST		= 127,	// =>CC2500
@@ -801,6 +802,7 @@ Serial: 100000 Baud 8e2      _ xxxx xxxx p --
 				JJRC345		71
 				Q90C		72
 				KYOSHO		73
+				RLINK		74
    BindBit=>		0x80	1=Bind/0=No
    AutoBindBit=>	0x40	1=Yes /0=No
    RangeCheck=>		0x20	1=Yes /0=No

Multiprotocol/Multiprotocol.ino

@@ -768,7 +768,7 @@ bool Update_All()
 	update_led_status();
 	#if defined(TELEMETRY)
 		#if ( !( defined(MULTI_TELEMETRY) || defined(MULTI_STATUS) ) )
-			if((protocol == PROTO_BAYANG_RX) || (protocol == PROTO_AFHDS2A_RX) || (protocol == PROTO_FRSKY_RX) || (protocol == PROTO_SCANNER) || (protocol==PROTO_FRSKYD) || (protocol==PROTO_BAYANG) || (protocol==PROTO_NCC1701) || (protocol==PROTO_BUGS) || (protocol==PROTO_BUGSMINI) || (protocol==PROTO_HUBSAN) || (protocol==PROTO_AFHDS2A) || (protocol==PROTO_FRSKYX) || (protocol==PROTO_FRSKYX2) || (protocol==PROTO_DSM) || (protocol==PROTO_CABELL) || (protocol==PROTO_HITEC) || (protocol==PROTO_HOTT) || (protocol==PROTO_PROPEL) || (protocol==PROTO_DEVO) || (protocol==PROTO_DSM_RX) || (protocol==PROTO_FRSKY_R9))
+			if((protocol == PROTO_BAYANG_RX) || (protocol == PROTO_AFHDS2A_RX) || (protocol == PROTO_FRSKY_RX) || (protocol == PROTO_SCANNER) || (protocol==PROTO_FRSKYD) || (protocol==PROTO_BAYANG) || (protocol==PROTO_NCC1701) || (protocol==PROTO_BUGS) || (protocol==PROTO_BUGSMINI) || (protocol==PROTO_HUBSAN) || (protocol==PROTO_AFHDS2A) || (protocol==PROTO_FRSKYX) || (protocol==PROTO_FRSKYX2) || (protocol==PROTO_DSM) || (protocol==PROTO_CABELL) || (protocol==PROTO_HITEC) || (protocol==PROTO_HOTT) || (protocol==PROTO_PROPEL) || (protocol==PROTO_DEVO) || (protocol==PROTO_DSM_RX) || (protocol==PROTO_FRSKY_R9) || (protocol==PROTO_RLINK))
 		#endif
 				if(IS_DISABLE_TELEM_off)
 					TelemetryUpdate();
@@ -1254,6 +1254,14 @@ static void protocol_init()
 						remote_callback = ESKY150V2_callback;
 						break;
 				#endif
+				#if defined(RLINK_CC2500_INO)
+					case PROTO_RLINK:
+						PE1_off;
+						PE2_on;	//antenna RF2
+						next_callback = initRLINK();
+						remote_callback = RLINK_callback;
+						break;
+				#endif
 			#endif
 			#ifdef CYRF6936_INSTALLED
 				#if defined(DSM_CYRF6936_INO)
@@ -2191,7 +2199,7 @@ void pollBoot()
 #if defined(TELEMETRY)
 void PPM_Telemetry_serial_init()
 {
-	if( (protocol==PROTO_FRSKYD) || (protocol==PROTO_HUBSAN) || (protocol==PROTO_AFHDS2A) || (protocol==PROTO_BAYANG)|| (protocol==PROTO_NCC1701) || (protocol==PROTO_CABELL)  || (protocol==PROTO_HITEC) || (protocol==PROTO_BUGS) || (protocol==PROTO_BUGSMINI) || (protocol==PROTO_PROPEL)
+	if( (protocol==PROTO_FRSKYD) || (protocol==PROTO_HUBSAN) || (protocol==PROTO_AFHDS2A) || (protocol==PROTO_BAYANG)|| (protocol==PROTO_NCC1701) || (protocol==PROTO_CABELL)  || (protocol==PROTO_HITEC) || (protocol==PROTO_BUGS) || (protocol==PROTO_BUGSMINI) || (protocol==PROTO_PROPEL) || (protocol==PROTO_RLINK)
 	#ifdef TELEMETRY_FRSKYX_TO_FRSKYD
 		 || (protocol==PROTO_FRSKYX) || (protocol==PROTO_FRSKYX2)
 	#endif

Multiprotocol/RadioLink_cc2500.ino

@@ -0,0 +1,209 @@
+/*
+ This project is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Multiprotocol is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Multiprotocol.  If not, see <http://www.gnu.org/licenses/>.
+ */
+// Radiolink surface protocol. TXs: RC4GS,RC6GS. Compatible RXs:R7FG(Std),R6FG,R6F,R8EF,R8FM,R8F,R4FGM 
+
+#if defined(RLINK_CC2500_INO)
+
+#include "iface_cc2500.h"
+
+#define RLINK_FORCE_ID
+
+#define RLINK_TX_PACKET_LEN	33
+#define RLINK_RX_PACKET_LEN	15
+#define RLINK_TX_ID_LEN		4
+
+enum {
+	RLINK_DATA	= 0x00,
+	RLINK_RX1	= 0x01,
+	RLINK_RX2	= 0x02,
+};
+
+const PROGMEM uint8_t RLINK_init_values[] = {
+  /* 00 */ 0x5B, 0x06, 0x5C, 0x07, 0xAB, 0xCD, 0x40, 0x04,
+  /* 08 */ 0x45, 0x00, 0x00, 0x06, 0x00, 0x5C, 0x62, 0x76,
+  /* 10 */ 0x7A, 0x7F, 0x13, 0x23, 0xF8, 0x44, 0x07, 0x30,
+  /* 18 */ 0x18, 0x16, 0x6C, 0x43, 0x40, 0x91, 0x87, 0x6B,
+  /* 20 */ 0xF8, 0x56, 0x10, 0xA9, 0x0A, 0x00, 0x11
+};
+
+static void __attribute__((unused)) RLINK_init()
+{
+	rf_ch_num=(random(0xfefefefe)&0x0F)+1;		// 0x01..0x10
+	memcpy(hopping_frequency,"\x12\xBA\x66\x72\x1E\x42\x06\x4E\x36\xAE\x8A\xA2\x2A\x7E\x96\x5A",16);
+	hopping_frequency[rf_ch_num]=0xC6;
+	#ifdef RLINK_FORCE_ID
+		memcpy(rx_tx_addr,"\x3A\x99\x22\x3A",RLINK_TX_ID_LEN);
+	#endif
+}
+
+static void __attribute__((unused)) RLINK_rf_init()
+{
+	CC2500_Strobe(CC2500_SIDLE);
+
+	for (uint8_t i = 0; i < 39; ++i)
+		CC2500_WriteReg(i, pgm_read_byte_near(&RLINK_init_values[i]));
+
+	prev_option = option;
+	CC2500_WriteReg(CC2500_0C_FSCTRL0, option);
+	
+	CC2500_SetTxRxMode(TX_EN);
+	CC2500_SetPower();
+}
+
+static void __attribute__((unused)) RLINK_tune_freq()
+{
+	if ( prev_option != option )
+	{
+		CC2500_WriteReg(CC2500_0C_FSCTRL0, option);
+		prev_option = option ;
+	}
+}
+
+static void __attribute__((unused)) RLINK_TIMING_RFSEND_packet()
+{
+	uint32_t pseudo=0, bits = 0;
+	uint8_t bitsavailable = 0;
+	uint8_t idx = 6;
+
+	CC2500_Strobe(CC2500_SIDLE);
+
+	// packet length
+	packet[0] = RLINK_TX_PACKET_LEN;
+	// header
+	packet[1] = packet_count>3?0x03:0x01;	// packet type: 0x01 normal, 0x03 request telemetry
+	//if(RX_num) packet[1] |= ((RX_num+2)<<4)+4;	// RX number limited to 10 values, 0 is a wildcard
+	
+	// ID
+	memcpy(&packet[2],rx_tx_addr,RLINK_TX_ID_LEN);
+
+	// pack 16 channels on 11 bits values between 170 and 1876, 1023 middle. The last 8 channels are failsafe values associated to the first 8 values.
+	for (uint8_t i = 0; i < 16; i++)
+	{
+		uint32_t val = convert_channel_16b_nolimit(i,170,1876);		// allow extended limits
+		if (val & 0x8000)
+			val = 0;
+		else if (val > 2047)
+			val=2047;
+
+		bits |= val << bitsavailable;
+		bitsavailable += 11;
+		while (bitsavailable >= 8) {
+			packet[idx++] = bits & 0xff;
+			bits >>= 8;
+			bitsavailable -= 8;
+		}
+	}
+	
+	// hop
+	pseudo=((pseudo * 0xAA) + 3) % 0x7673;	// calc next pseudo random value
+	CC2500_WriteReg(CC2500_0A_CHANNR, hopping_frequency[pseudo &0x0F]);
+	packet[28]= pseudo;
+	packet[29]= pseudo >> 8;
+	packet[30]= 0x00;						// unknown
+	packet[31]= 0x00;						// unknown
+	packet[32]= rf_ch_num;					// value equal to 0xC6 in the RF table
+	
+	// check
+	uint8_t sum=0;
+	for(uint8_t i=0;i<33;i++)
+		sum+=packet[i];
+	packet[33]=sum;
+
+	// send packet
+	CC2500_WriteData(packet, RLINK_TX_PACKET_LEN+1);
+	
+	// packets type
+	packet_count++;
+	if(packet_count>6) packet_count=0;
+}
+
+#define RLINK_TIMING_PROTO	20000
+#define RLINK_TIMING_RFSEND	10223
+#define RLINK_TIMING_CHECK	2000
+uint16_t RLINK_callback()
+{
+	switch(phase)
+	{
+		case RLINK_DATA:
+			#ifdef MULTI_SYNC
+				telemetry_set_input_sync(RLINK_TIMING_PROTO);
+			#endif
+			RLINK_tune_freq();
+			RLINK_TIMING_RFSEND_packet();
+#if not defined RLINK_HUB_TELEMETRY
+				return RLINK_TIMING_PROTO;
+#else
+			if(packet[1]==0x01)
+				return RLINK_TIMING_PROTO;
+			phase++;										// RX1
+			return RLINK_TIMING_RFSEND;
+		case RLINK_RX1:
+			CC2500_Strobe(CC2500_SIDLE);
+			CC2500_Strobe(CC2500_SFRX);
+			CC2500_SetTxRxMode(RX_EN);
+			CC2500_Strobe(CC2500_SRX);
+			phase++;										// RX2
+			return RLINK_TIMING_PROTO-RLINK_TIMING_RFSEND-RLINK_TIMING_CHECK;
+		case RLINK_RX2:
+			len = CC2500_ReadReg(CC2500_3B_RXBYTES | CC2500_READ_BURST) & 0x7F;	
+			if (len == RLINK_RX_PACKET_LEN + 1 + 2)			//Telemetry frame is 15 bytes + 1 byte for length + 2 bytes for RSSI&LQI&CRC
+			{
+				//debug("Telem:");
+				CC2500_ReadData(packet_in, len);
+				if(packet_in[0]==RLINK_RX_PACKET_LEN && (packet_in[len-1] & 0x80) && memcmp(&packet[2],rx_tx_addr,RLINK_TX_ID_LEN)==0 && packet_in[6]==0x03)
+				{//Correct telemetry received: length, CRC, ID and type
+					//Debug
+					//for(uint8_t i=0;i<len;i++)
+					//	debug(" %02X",packet_in[i]);
+					TX_RSSI = packet_in[len-2];
+					if(TX_RSSI >=128)
+						TX_RSSI -= 128;
+					else
+						TX_RSSI += 128;
+					RX_RSSI=packet_in[7];					//Should be packet_in[7]-256 but since it's an uint8_t...
+					v_lipo1=packet_in[8];
+					v_lipo2=packet_in[9];
+					telemetry_link=1;						//Send telemetry out
+					pps_counter++;
+					packet_count=0;
+				}
+				//debugln("");
+			}
+			if (millis() - pps_timer >= 2000)
+			{//1 packet every 20ms
+				pps_timer = millis();
+				debugln("%d pps", pps_counter);
+				TX_LQI = pps_counter;						//Max=100%
+				pps_counter = 0;
+			}
+			CC2500_SetTxRxMode(TX_EN);
+			phase=RLINK_DATA;								// DATA
+			return RLINK_TIMING_CHECK;
+#endif
+	}
+	return 0;
+}
+
+uint16_t initRLINK()
+{
+	BIND_DONE;	// Not a TX bind protocol
+	RLINK_init();
+	RLINK_rf_init();
+	packet_count = 0;
+	phase = RLINK_DATA;
+	return 10000;
+}
+
+#endif

Multiprotocol/Telemetry.ino

@@ -531,7 +531,7 @@ void frsky_link_frame()
 		telemetry_link |= 2 ;		// Send hub if available
 	}
 	else
-	{//PROTO_HUBSAN, PROTO_AFHDS2A, PROTO_BAYANG, PROTO_NCC1701, PROTO_CABELL, PROTO_HITEC, PROTO_BUGS, PROTO_BUGSMINI, PROTO_FRSKYX, PROTO_FRSKYX2, PROTO_PROPEL, PROTO_DEVO
+	{//PROTO_HUBSAN, PROTO_AFHDS2A, PROTO_BAYANG, PROTO_NCC1701, PROTO_CABELL, PROTO_HITEC, PROTO_BUGS, PROTO_BUGSMINI, PROTO_FRSKYX, PROTO_FRSKYX2, PROTO_PROPEL, PROTO_DEVO, PROTO_RLINK
 		frame[1] = v_lipo1;
 		frame[2] = v_lipo2;
 		frame[3] = RX_RSSI;
@@ -952,7 +952,7 @@ void TelemetryUpdate()
 	#endif
 
 		if( telemetry_link & 1 )
-		{	// FrSkyD + Hubsan + AFHDS2A + Bayang + Cabell + Hitec + Bugs + BugsMini + NCC1701 + PROPEL
+		{	// FrSkyD + Hubsan + AFHDS2A + Bayang + Cabell + Hitec + Bugs + BugsMini + NCC1701 + PROPEL + RLINK
 			// FrSkyX telemetry if in PPM
 			frsky_link_frame();
 			return;

Multiprotocol/Validate.h

@@ -243,6 +243,7 @@
 	#undef	HITEC_CC2500_INO
 	#undef	HOTT_CC2500_INO
 	#undef	REDPINE_CC2500_INO
+	#undef	RLINK_CC2500_INO
 	#undef	SCANNER_CC2500_INO
 	#undef	SFHSS_CC2500_INO
 	#undef	SKYARTEC_CC2500_INO
@@ -332,6 +333,7 @@
 	#undef BAYANG_RX_NRF24L01_INO
 	#undef DEVO_HUB_TELEMETRY
 	#undef PROPEL_HUB_TELEMETRY
+	#undef RLINK_HUB_TELEMETRY
 	#undef DSM_RX_CYRF6936_INO
 #else
 	#if defined(MULTI_TELEMETRY) && defined(MULTI_STATUS)
@@ -371,6 +373,9 @@
 	#if not defined(CABELL_NRF24L01_INO)
 		#undef CABELL_HUB_TELEMETRY
 	#endif
+	#if not defined(RLINK_CC2500_INO)
+		#undef RLINK_HUB_TELEMETRY
+	#endif
 	#if not defined(HUBSAN_A7105_INO)
 		#undef HUBSAN_HUB_TELEMETRY
 	#endif
@@ -398,7 +403,7 @@
 	#if not defined(HOTT_CC2500_INO)
 		#undef HOTT_FW_TELEMETRY
 	#endif
-	#if not defined(HOTT_FW_TELEMETRY) && not defined(DSM_TELEMETRY) && not defined(SPORT_TELEMETRY) && not defined(HUB_TELEMETRY) && not defined(HUBSAN_HUB_TELEMETRY) && not defined(BUGS_HUB_TELEMETRY) && not defined(NCC1701_HUB_TELEMETRY) && not defined(BAYANG_HUB_TELEMETRY) && not defined(CABELL_HUB_TELEMETRY) && not defined(AFHDS2A_HUB_TELEMETRY) && not defined(AFHDS2A_FW_TELEMETRY) && not defined(MULTI_TELEMETRY) && not defined(MULTI_STATUS) && not defined(HITEC_HUB_TELEMETRY) && not defined(HITEC_FW_TELEMETRY) && not defined(SCANNER_TELEMETRY) && not defined(FRSKY_RX_TELEMETRY) && not defined(AFHDS2A_RX_TELEMETRY) && not defined(BAYANG_RX_TELEMETRY) && not defined(DEVO_HUB_TELEMETRY) && not defined(PROPEL_HUB_TELEMETRY)
+	#if not defined(HOTT_FW_TELEMETRY) && not defined(DSM_TELEMETRY) && not defined(SPORT_TELEMETRY) && not defined(HUB_TELEMETRY) && not defined(HUBSAN_HUB_TELEMETRY) && not defined(BUGS_HUB_TELEMETRY) && not defined(NCC1701_HUB_TELEMETRY) && not defined(BAYANG_HUB_TELEMETRY) && not defined(CABELL_HUB_TELEMETRY) && not defined(RLINK_HUB_TELEMETRY) && not defined(AFHDS2A_HUB_TELEMETRY) && not defined(AFHDS2A_FW_TELEMETRY) && not defined(MULTI_TELEMETRY) && not defined(MULTI_STATUS) && not defined(HITEC_HUB_TELEMETRY) && not defined(HITEC_FW_TELEMETRY) && not defined(SCANNER_TELEMETRY) && not defined(FRSKY_RX_TELEMETRY) && not defined(AFHDS2A_RX_TELEMETRY) && not defined(BAYANG_RX_TELEMETRY) && not defined(DEVO_HUB_TELEMETRY) && not defined(PROPEL_HUB_TELEMETRY)
 		#undef TELEMETRY
 		#undef INVERT_TELEMETRY
 		#undef MULTI_TELEMETRY

Multiprotocol/_Config.h

@@ -197,6 +197,7 @@
 #define	SFHSS_CC2500_INO
 #define	SKYARTEC_CC2500_INO
 #define	REDPINE_CC2500_INO
+#define	RLINK_CC2500_INO
 
 //The protocols below need a NRF24L01 to be installed
 #define	ASSAN_NRF24L01_INO
@@ -313,6 +314,7 @@
 #define NCC1701_HUB_TELEMETRY		// Use FrSkyD Hub format to send telemetry to TX
 #define PROPEL_HUB_TELEMETRY		// Use FrSkyD Hub format to send telemetry to TX
 #define CABELL_HUB_TELEMETRY		// Use FrSkyD Hub format to send telemetry to TX
+#define RLINK_HUB_TELEMETRY			// Use FrSkyD Hub format to send telemetry to TX
 #define HITEC_HUB_TELEMETRY			// Use FrSkyD Hub format to send basic telemetry to the radios which can decode it like er9x, erskyTX and OpenTX
 #define HITEC_FW_TELEMETRY			// Forward received telemetry packets to be decoded by erskyTX and OpenTX
 #define SCANNER_TELEMETRY			// Forward spectrum scanner data to TX
@@ -699,6 +701,8 @@ const PPM_Parameters PPM_prot[14*NBR_BANKS]=	{
 	PROTO_REDPINE
 		RED_FAST
 		RED_SLOW
+	PROTO_RLINK
+		NONE
 	PROTO_SCANNER
 		NONE
 	PROTO_SFHSS

Protocols_Details.md

@@ -117,6 +117,7 @@ CFlie|38|CFlie||||||||NRF24L01|
 [Q2X2](Protocols_Details.md#Q2X2---29)|29|Q222|Q242|Q282||||||NRF24L01|
 [Q303](Protocols_Details.md#Q303---31)|31|Q303|CX35|CX10D|CX10WD|||||NRF24L01|XN297
 [Q90C](Protocols_Details.md#Q90C---72)|72|Q90C*||||||||NRF24L01|XN297
+[RadioLink](Protocols_Details.md#RadioLink---74)|74|Surface||||||||CC2500|
 [Redpine](Protocols_Details.md#Redpine---50)|50|FAST|SLOW|||||||NRF24L01|
 [Scanner](Protocols_Details.md#Scanner---54)|54|||||||||CC2500|
 [SFHSS](Protocols_Details.md#SFHSS---21)|21|SFHSS||||||||CC2500|
@@ -545,6 +546,24 @@ You should definitively upgrade your receivers/sensors to the latest firmware ve
 ## Scanner - *54*
 2.4GHz scanner accessible using the OpenTX 2.3 Spectrum Analyser tool.
 
+## RadioLink - *74*
+
+Extended limits
+
+Option for this protocol corresponds to fine frequency tuning. This value is different for each Module and **must** be accurate otherwise the link will not be stable.
+Check the [Frequency Tuning page](/docs/Frequency_Tuning.md) to determine it.
+
+CH1|CH2|CH3|CH4|CH5|CH6|CH7|CH8|CH9|CH10|CH11|CH12|CH13|CH14|CH15|CH16
+---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---
+CH1|CH2|CH3|CH4|CH5|CH6|CH7|CH8|FS_CH1|FS_CH2|FS_CH3|FS_CH4|FS_CH5|FS_CH6|FS_CH7|FS_CH8
+
+FS=FailSafe
+
+### Sub_protocol Surface - *0*
+Surface protocol. TXs: RC4GS,RC6GS. Compatible RXs:R7FG(Std),R6FG,R6F,R8EF,R8FM,R8F,R4FGM
+
+CH1=Steering, CH2=Throttle, CH8=Gyro gain
+
 ## SFHSS - *21*
 Models: Futaba RXs and XK models.