New FrSkyX protocol

diff --git a/src/protocol/frskyx_cc2500.c b/src/protocol/frskyx_cc2500.c
index 5cfd12e..8aa8bf5 100644
--- a/src/protocol/frskyx_cc2500.c
+++ b/src/protocol/frskyx_cc2500.c
@@ -219,6 +219,8 @@ static u16 scaleForPXX(u8 chan, u8 failsafe)
     
     chan_val = chan_val * STICK_SCALE / CHAN_MAX_VALUE + 1024;
 
+    if (chan == 11 && !failsafe) chan_val = Telemetry.value[TELEM_FRSKY_RSSI];
+
     if (chan_val > 2046)   chan_val = 2046;
     else if (chan_val < 1) chan_val = 1;

diff --git a/src/config/model.h b/src/config/model.h
index a227ba7..3a75cde 100644
--- a/src/config/model.h
+++ b/src/config/model.h
@@ -21,7 +21,7 @@ const char *MODEL_TEMPLATE;
 #define UNKNOWN_ICON ("media/noicon" IMG_EXT)

 //This cannot be computed, and must be manually updated
-#define NUM_PROTO_OPTS 4
+#define NUM_PROTO_OPTS 5
 #define VIRT_NAME_LEN 10

 struct Model {
diff --git a/src/protocol/frskyx_cc2500.c b/src/protocol/frskyx_cc2500.c
index 5cfd12e..b02ae73 100644
--- a/src/protocol/frskyx_cc2500.c
+++ b/src/protocol/frskyx_cc2500.c
@@ -42,6 +42,7 @@ static const char * const frskyx_opts[] = {
   _tr_noop("AD2GAIN"),  "0", "2000", "655361", NULL,       // big step 10, little step 1
   _tr_noop("Freq-Fine"),  "-127", "127", NULL,
   _tr_noop("Format"),  "FCC", "EU", NULL,
+  _tr_noop("RSSIChan"),  "None", "LastChan", NULL,
   NULL
 };
 enum {
@@ -49,6 +50,7 @@ enum {
     PROTO_OPTS_AD2GAIN,
     PROTO_OPTS_FREQFINE,
     PROTO_OPTS_FORMAT,
+    PROTO_OPTS_RSSICHAN,
     LAST_PROTO_OPT,
 };
 ctassert(LAST_PROTO_OPT <= NUM_PROTO_OPTS, too_many_protocol_opts);
@@ -217,7 +219,10 @@ static u16 scaleForPXX(u8 chan, u8 failsafe)
     else
         chan_val = Channels[chan];

-    chan_val = chan_val * STICK_SCALE / CHAN_MAX_VALUE + 1024;
+    if (Model.proto_opts[PROTO_OPTS_RSSICHAN] && (chan == Model.num_channels - 1) && !failsafe)
+        chan_val = Telemetry.value[TELEM_FRSKY_RSSI] * 21;      // Max RSSI value seems to be 99, scale it to around 2000
+    else
+        chan_val = chan_val * STICK_SCALE / CHAN_MAX_VALUE + 1024;

     if (chan_val > 2046)   chan_val = 2046;
     else if (chan_val < 1) chan_val = 1;