diff --git a/src/board_ersky9x.h b/src/board_ersky9x.h
index e5de85e56..6981ac24f 100644
--- a/src/board_ersky9x.h
+++ b/src/board_ersky9x.h
@@ -40,6 +40,7 @@
 
 extern "C" {
 extern void init_SDcard();
+extern void sdInit();
 extern void sdPoll10mS();
 }
 
diff --git a/src/eeprom_arm.cpp b/src/eeprom_arm.cpp
index d1dbda47e..c90fef6e5 100644
--- a/src/eeprom_arm.cpp
+++ b/src/eeprom_arm.cpp
@@ -466,7 +466,7 @@ bool ee32LoadGeneral()
 
 void eeLoadModel(uint8_t id)
 {
-  uint16_t size ;
+  uint16_t size;
 
   if (id<MAX_MODELS) {
 
@@ -474,6 +474,8 @@ void eeLoadModel(uint8_t id)
       pausePulses();
     }
 
+    pauseMixerCalculations();
+
     size =  File_system[id+1].size ;
 
     memset(&g_model, 0, sizeof(g_model));
@@ -508,6 +510,9 @@ void eeLoadModel(uint8_t id)
 
     resetProto();
     resetAll();
+
+    resumeMixerCalculations();
+    // TODO pulses should be started after mixer calculations ...
   }
 }
 
diff --git a/src/ersky9x/diskio.c b/src/ersky9x/diskio.c
index ee1a5f70b..bea741193 100644
--- a/src/ersky9x/diskio.c
+++ b/src/ersky9x/diskio.c
@@ -874,6 +874,60 @@ void sdPoll10mS()
   }
 }
 
+void sdInit()
+{
+  Sd_rca = 0;
+  sdErrorCount = 0;
+
+  Card_state = SD_ST_EMPTY;
+  if (!CardIsConnected())
+    return;
+
+  Card_state = SD_ST_INIT1;
+  sdCmd0();
+
+  Card_state = SD_ST_INIT2;
+  sdCmd8(1);
+
+  Card_state = SD_ST_IDLE;
+  sdMemInit(1, &Cmd_A41_resp);
+
+  Card_state = SD_ST_READY;
+  uint8_t retry;
+  for (retry=0; retry<10; retry++) {
+    if (!sdCmd2()) break;
+    CoTickDelay(1);  // 2ms
+  }
+
+  if (retry == 10)
+    return;
+
+  Card_state = SD_ST_IDENT;
+
+  for (retry=0; retry<10; retry++) {
+    if (!sdCmd3()) break;
+    CoTickDelay(1);  // 2ms
+  }
+
+  if (retry == 10)
+    return;
+
+  Card_state = SD_ST_STBY;
+  sdCmd9();
+  sdCmd7(); // Select Card
+
+  Card_state = SD_ST_TRAN;
+  sdAcmd51();
+  sdAcmd6(); // Set bus width to 4 bits, and speed to 9 MHz
+
+  // Should check the card can do this ****
+  Card_state = SD_ST_DATA;
+
+  f_mount(0, &g_FATFS_Obj);
+  retrieveAvailableAudioFiles();
+  Card_state = SD_ST_MOUNTED;
+}
+
 // Checks for card ready for read/write
 // returns 1 for YES, 0 for NO
 uint32_t sd_card_ready( void )
diff --git a/src/model_menus.cpp b/src/model_menus.cpp
index d7c4486f4..7186cb679 100644
--- a/src/model_menus.cpp
+++ b/src/model_menus.cpp
@@ -1328,25 +1328,6 @@ bool reachExpoMixCountLimit(uint8_t expo)
   return false;
 }
 
-#if defined(PCBV4)
-inline void pauseMixerCalculations()
-{
-  cli();
-  TIMSK5 &= ~(1<<OCIE5A);
-  sei();
-}
-
-inline void resumeMixerCalculations()
-{
-  cli();
-  TIMSK5 |= (1<<OCIE5A);
-  sei();
-}
-#else
-#define pauseMixerCalculations()
-#define resumeMixerCalculations()
-#endif
-
 void deleteExpoMix(uint8_t expo, uint8_t idx)
 {
   pauseMixerCalculations();
@@ -1553,12 +1534,6 @@ void menuProcExpoOne(uint8_t event)
         lcd_outdezAtt(EXPO_ONE_2ND_COLUMN+3*FW, y, ed->weight, attr|INFLIGHT((int8_t&)ed->weight));
         if (attr) CHECK_INFLIGHT_INCDEC_MODELVAR(event, (int8_t&)ed->weight, 0, 100, 0, STR_DRWEIGHT);
         break;
-#if defined(PCBARM)
-      case EXPO_FIELD_EXPO:
-        lcd_outdezAtt(EXPO_ONE_2ND_COLUMN+3*FW, y, ed->expo, attr|INFLIGHT(ed->expo));
-        if (attr) CHECK_INFLIGHT_INCDEC_MODELVAR(event, ed->expo, -100, 100, 0, STR_DREXPO);
-        break;
-#else
       case EXPO_FIELD_EXPO:
         if (ed->curveMode==MODE_EXPO || ed->curveParam==0) {
           ed->curveMode = MODE_EXPO;
@@ -1569,20 +1544,7 @@ void menuProcExpoOne(uint8_t event)
           lcd_putsAtt(EXPO_ONE_2ND_COLUMN, y, STR_NA, attr);
         }
         break;
-#endif
 #if defined(CURVES)
-#if defined(PCBARM)
-      case EXPO_FIELD_CURVE:
-        putsCurve(EXPO_ONE_2ND_COLUMN, y, ed->curve, attr);
-        if (attr) {
-          CHECK_INCDEC_MODELVAR(event, ed->curve, 0, CURVE_BASE+MAX_CURVES-1);
-          if (ed->curve>=CURVE_BASE && event==EVT_KEY_FIRST(KEY_MENU)) {
-            s_curveChan = ed->curve - CURVE_BASE;
-            pushMenu(menuProcCurveOne);
-          }
-        }
-        break;
-#else
       case EXPO_FIELD_CURVE:
         if (ed->curveMode!=MODE_EXPO || ed->curveParam==0) {
           putsCurve(EXPO_ONE_2ND_COLUMN, y, ed->curveParam, attr);
@@ -1600,7 +1562,6 @@ void menuProcExpoOne(uint8_t event)
         }
         break;
 #endif
-#endif
 #if defined(FLIGHT_PHASES)
       case EXPO_FIELD_FLIGHT_PHASE:
         ed->phases = editPhases(EXPO_ONE_2ND_COLUMN-2*FW, y, event, ed->phases, attr);
@@ -2000,17 +1961,10 @@ void menuProcExpoMix(uint8_t expo, uint8_t _event_)
               CHECK_INCDEC_MODELVAR(_event, ed->weight, 0, 100);
             }
 
-#if defined(PCBARM)
-            if (ed->curve)
-              putsCurve(EXPO_LINE_EXPO_POS-3*FW, y, ed->curve);
-            else if (ed->expo)
-              lcd_outdezAtt(EXPO_LINE_EXPO_POS, y, ed->expo, 0);
-#else
             if (ed->curveMode == MODE_CURVE)
               putsCurve(EXPO_LINE_EXPO_POS-3*FW, y, ed->curveParam);
             else
               lcd_outdezAtt(EXPO_LINE_EXPO_POS, y, ed->curveParam, 0);
-#endif
 
 #if defined(PCBARM)
             if (ed->name[0]) {
diff --git a/src/myeeprom.h b/src/myeeprom.h
index 7fddc85e2..cd8df55c2 100644
--- a/src/myeeprom.h
+++ b/src/myeeprom.h
@@ -172,12 +172,12 @@ PACK(typedef struct t_EEGeneral {
 PACK(typedef struct t_ExpoData {
   uint8_t mode;         // 0=end, 1=pos, 2=neg, 3=both
   uint8_t chn;
-  int8_t  curve;        // 0=no curve, 1-6=std curves, 7-22=CV1-CV16
   int8_t  swtch;
   uint16_t phases;
   int8_t  weight;
+  uint8_t curveMode;
   char    name[6];
-  int8_t  expo;
+  int8_t  curveParam;
 }) ExpoData;
 #else
 PACK(typedef struct t_ExpoData {
diff --git a/src/open9x.cpp b/src/open9x.cpp
index 85a02466f..ccefa2a16 100644
--- a/src/open9x.cpp
+++ b/src/open9x.cpp
@@ -32,10 +32,6 @@
  */
 
 #if defined(PCBARM) && !defined(SIMU)
-extern "C" {
-#include <CoOS.h>
-}
-
 #define MIXER_STACK_SIZE    500
 #define MENUS_STACK_SIZE    1000
 #define AUDIO_STACK_SIZE    500
@@ -54,6 +50,7 @@ OS_FlagID audioFlag;
 
 OS_MutexID sdMutex;
 OS_MutexID audioMutex;
+OS_MutexID mixerMutex;
 
 /*OS_TID btTask;
 OS_STK btStack[BT_STACK_SIZE];
@@ -433,19 +430,12 @@ void applyExpos(int16_t *anas)
       int16_t v = anas2[ed.chn];
       if((v<0 && ed.mode&1) || (v>=0 && ed.mode&2)) {
         cur_chn = ed.chn;
-#if defined(PCBARM)
-        if (ed.curve)
-          v = applyCurve(v, ed.curve);
-        if (ed.expo)
-          v = expo(v, ed.expo);
-#else
         if (ed.curveParam) {
           if (ed.curveMode == MODE_CURVE)
             v = applyCurve(v, ed.curveParam);
           else
             v = expo(v, ed.curveParam);
         }
-#endif
         v = ((int32_t)v * ed.weight) / 100;
         anas[cur_chn] = v;
       }
@@ -998,8 +988,6 @@ void doSplash()
     lcdSetRefVolt(contrast);
 #endif
 
-    clearKeyEvents();
-
 #ifndef SIMU
     for(uint8_t i=0; i<32; i++)
       getADC_filt(); // init ADC array
@@ -3116,8 +3104,6 @@ inline void open9xInit(OPEN9X_INIT_ARGS)
   }
 #endif
 
-  clearKeyEvents(); //make sure no keys are down before proceeding
-
   lcdSetRefVolt(g_eeGeneral.contrast);
   backlightOn();
 
@@ -3149,7 +3135,9 @@ void mixerTask(void * pdata)
 
       if (s_current_protocol < PROTO_NONE) {
         if (tick10ms) checkTrims();
+        CoEnterMutexSection(mixerMutex);
         doMixerCalculations(tmr10ms, tick10ms);
+        CoLeaveMutexSection(mixerMutex);
       }
 
       heartbeat |= HEART_TIMER10ms;
@@ -3717,13 +3705,15 @@ int main(void)
   init_rotary_sw();
 #endif
 
-#ifndef PCBARM
+#if !defined(PCBARM)
   open9xInit(mcusr);
 #endif
 
 #if defined(PCBARM)
   CoInitOS();
 
+  sdInit();
+
   // btFlag = CoCreateFlag(TRUE, FALSE);          // Auto-reset, start FALSE
   // btTimer = CoCreateTmr(TMR_TYPE_PERIODIC, 1000/(1000/CFG_SYSTICK_FREQ), 1000/(1000/CFG_SYSTICK_FREQ), btTimerHandle);
 
@@ -3737,6 +3727,7 @@ int main(void)
 
   sdMutex = CoCreateMutex();
   audioMutex = CoCreateMutex();
+  mixerMutex = CoCreateMutex();
 
   CoStartOS();
 #else
diff --git a/src/open9x.h b/src/open9x.h
index 0d12e1b8b..38ff7ca83 100644
--- a/src/open9x.h
+++ b/src/open9x.h
@@ -729,6 +729,42 @@ template<class t> FORCEINLINE t limit(t mi, t x, t ma) { return min(max(mi,x),ma
 uint16_t isqrt32(uint32_t n);
 #endif
 
+#if defined(PCBARM)
+#if !defined(SIMU)
+extern "C" {
+#include <CoOS.h>
+}
+#endif
+
+extern OS_MutexID mixerMutex;
+inline void pauseMixerCalculations()
+{
+  CoEnterMutexSection(mixerMutex);
+}
+
+inline void resumeMixerCalculations()
+{
+  CoLeaveMutexSection(mixerMutex);
+}
+#elif defined(PCBV4)
+inline void pauseMixerCalculations()
+{
+  cli();
+  TIMSK5 &= ~(1<<OCIE5A);
+  sei();
+}
+
+inline void resumeMixerCalculations()
+{
+  cli();
+  TIMSK5 |= (1<<OCIE5A);
+  sei();
+}
+#else
+#define pauseMixerCalculations()
+#define resumeMixerCalculations()
+#endif
+
 /// Markiert einen EEPROM-Bereich als dirty. der Bereich wird dann in
 /// eeCheck ins EEPROM zurueckgeschrieben.
 void eeWriteBlockCmp(const void *i_pointer_ram, uint16_t i_pointer_eeprom, size_t size);
diff --git a/src/sdcard.h b/src/sdcard.h
index e303a2a34..c40748888 100644
--- a/src/sdcard.h
+++ b/src/sdcard.h
@@ -68,8 +68,6 @@ inline const pm_char *SDCARD_ERROR(FRESULT result)
     return STR_SDCARD_ERROR;
 }
 
-extern void sdPoll10mS();
-
 #if defined(PCBARM) && !(defined(SIMU))
 extern "C" {
 extern uint32_t sd_card_ready();
diff --git a/src/simpgmspace.h b/src/simpgmspace.h
index 0c3634357..b03fe5516 100644
--- a/src/simpgmspace.h
+++ b/src/simpgmspace.h
@@ -295,6 +295,7 @@ void eeprom_read_block (void *pointer_ram,
 #define wdt_reset() sleep(1/*ms*/)
 #define board_init()
 
+#define OS_MutexID int
 #define CoSetFlag(...)
 #define CoClearFlag(...)
 #define CoSetTmrCnt(...)