diff --git a/main.c b/main.c
index 67fe4a0..eaaf20c 100644
--- a/main.c
+++ b/main.c
@@ -38,8 +38,8 @@
 
 extern uint32_t minFreq;
 extern uint32_t maxFreq;
-float frequencyStart;
-float frequencyStop;
+uint32_t frequencyStart;
+uint32_t frequencyStop;
 int32_t frequencyExtra;
 #define START_MIN minFreq
 #define STOP_MAX maxFreq
@@ -133,6 +133,7 @@ static THD_FUNCTION(Thread1, arg)
   ui_process();
 
   while (1) {
+//  START_PROFILE
     if (sweep_mode&(SWEEP_ENABLE|SWEEP_ONCE)) {
 //      if (dirty)
         completed = sweep(true);
@@ -151,6 +152,7 @@ static THD_FUNCTION(Thread1, arg)
 //      if (setting.mode != -1)
         __WFI();
     }
+//  STOP_PROFILE
     // Run Shell command in sweep thread
     if (shell_function) {
       operation_requested = OP_NONE; // otherwise commands  will be aborted
diff --git a/sa_cmd.c b/sa_cmd.c
index 6c2d0d2..2130e29 100644
--- a/sa_cmd.c
+++ b/sa_cmd.c
@@ -274,36 +274,18 @@ VNA_SHELL_FUNCTION(cmd_v)
     shell_printf("VFO %d\r\n", VFO);
 }
 
-int xtoi(char *t)
-{
-
-  int v=0;
-  while (*t) {
-    if ('0' <= *t && *t <= '9')
-      v = v*16 + *t - '0';
-    else if ('a' <= *t && *t <= 'f')
-      v = v*16 + *t - 'a' + 10;
-    else if ('A' <= *t && *t <= 'F')
-      v = v*16 + *t - 'A' + 10;
-    else
-      return v;
-    t++;
-  }
-  return v;
-}
-
 VNA_SHELL_FUNCTION(cmd_y)
 {
   int rvalue;
   int lvalue = 0;
   if (argc != 1 && argc != 2) {
-    shell_printf("usage: y {addr(0-95)} [value(0-FF)]\r\n");
+    shell_printf("usage: y {addr(0-95)} [value(0-0xFF)]\r\n");
     return;
   }
-  rvalue = xtoi(argv[0]);
+  rvalue = my_atoui(argv[0]);
   SI4432_Sel = VFO;
   if (argc == 2){
-    lvalue = xtoi(argv[1]);
+    lvalue = my_atoui(argv[1]);
     SI4432_Write_Byte(rvalue, lvalue);
   } else {
     lvalue = SI4432_Read_Byte(rvalue);
@@ -359,7 +341,7 @@ return;             // Don't use!!!!
   SI4432_Init();
   shell_printf("SI4432 init done\r\n");
   if (argc == 1) {
-    rvalue = xtoi(argv[0]);
+    rvalue = my_atoui(argv[0]);
     set_switches(rvalue);
     set_mode(rvalue);
     shell_printf("SI4432 mode %d set\r\n", rvalue);
@@ -389,10 +371,10 @@ VNA_SHELL_FUNCTION(cmd_a)
 {
   (void)argc;
   if (argc != 1) {
-    shell_printf("a=%d\r\n", frequencyStart);
+    shell_printf("a=%u\r\n", frequencyStart);
     return;
   }
-  int32_t value = my_atoi(argv[0]);
+  uint32_t value = my_atoui(argv[0]);
   frequencyStart = value;
 }
 
@@ -401,10 +383,10 @@ VNA_SHELL_FUNCTION(cmd_b)
 {
   (void)argc;
   if (argc != 1) {
-    shell_printf("b=%d\r\n", frequencyStop);
+    shell_printf("b=%u\r\n", frequencyStop);
     return;
   }
-  int32_t value = my_atoi(argv[0]);
+  uint32_t value = my_atoui(argv[0]);
   frequencyStop = value;
 }
 
@@ -443,20 +425,25 @@ VNA_SHELL_FUNCTION(cmd_s)
 
 void sweep_remote(void)
 {
-  int old_step = setting.frequency_step;
-  uint32_t f_step = (frequencyStop-frequencyStart)/ points;
-  setting.frequency_step = f_step;
+  uint32_t i;
+  uint32_t step = (points - 1);
+  uint32_t span = frequencyStop - frequencyStart;
+  uint32_t delta = span / step;
+  uint32_t error = span % step;
+  uint32_t f = frequencyStart - setting.frequency_IF, df = step>>1;
+  uint32_t old_step = setting.frequency_step;
+  setting.frequency_step = delta;
   streamPut(shell_stream, '{');
   dirty = true;
-  for (int i = 0; i<points; i++) {
+  for (i = 0; i <= step; i++, f+=delta) {
     if (operation_requested)
       break;
-    float val = perform(false, i, frequencyStart - setting.frequency_IF + f_step * i, false);
+    float val = perform(false, i, f, false);
     streamPut(shell_stream, 'x');
     int v = val*2 + 256;
     streamPut(shell_stream, (uint8_t)(v & 0xFF));
     streamPut(shell_stream, (uint8_t)((v>>8) & 0xFF));
-  // enable led
+    df+=error;if (df >=step) {f++;df -= step;}
   }
   streamPut(shell_stream, '}');
   setting.frequency_step = old_step;
diff --git a/si4432.c b/si4432.c
index 7e17dd6..bab4a4d 100644
--- a/si4432.c
+++ b/si4432.c
@@ -24,6 +24,9 @@
 #include <math.h>
 #include "si4432.h"
 
+#pragma GCC push_options
+#pragma GCC optimize ("O2")
+
 #define CS_SI0_HIGH     palSetPad(GPIOC, GPIO_RX_SEL)
 #define CS_SI1_HIGH     palSetPad(GPIOC, GPIO_LO_SEL)
 #define CS_PE_HIGH      palSetPad(GPIOC, GPIO_PE_SEL)
@@ -40,9 +43,10 @@
 
 #define SPI2_SDI_HIGH   palSetPad(GPIOB, GPIO_SPI2_SDI)
 #define SPI2_SDI_LOW    palClearPad(GPIOB, GPIO_SPI2_SDI)
+#define SPI2_RESET      palClearPort(GPIOB, (1<<GPIO_SPI2_CLK)|(1<<GPIO_SPI2_SDI))
 
-#define SPI2_SDO    ((palReadPort(GPIOB)>>GPIO_SPI2_SDO)&1)
-
+#define SPI2_SDO       ((palReadPort(GPIOB)>>GPIO_SPI2_SDO)&1)
+#define SPI2_portSDO   (palReadPort(GPIOB)&(1<<GPIO_SPI2_SDO))
 
 //#define MAXLOG 1024
 //unsigned char SI4432_logging[MAXLOG];
@@ -51,10 +55,11 @@
 //#define SI4432_log(X)   { if (log_index < MAXLOG)  SI4432_logging[log_index++] = X; }
 #define SI4432_log(X)
 
-void shiftOut(uint8_t val)
+static void shiftOut(uint8_t val)
 {
   SI4432_log(SI4432_Sel);
   SI4432_log(val);
+#if 0
   uint8_t i = 0;
   do {
     if (val & 0x80)
@@ -65,20 +70,32 @@ void shiftOut(uint8_t val)
     SPI2_CLK_HIGH;
     SPI2_CLK_LOW;
   }while((++i) & 0x07);
+#else
+  uint8_t i = 0;
+  do {
+    if (val & 0x80)
+      SPI2_SDI_HIGH;
+    SPI2_CLK_HIGH;
+    SPI2_RESET;
+    val<<=1;
+  }while((++i) & 0x07);
+#endif
 }
 
-uint8_t shiftIn(void) {
-  uint8_t value = 0;
+static uint8_t shiftIn(void)
+{
+  uint32_t value = 0;
   uint8_t i = 0;
   do {
+    value<<=1;
     SPI2_CLK_HIGH;
-    value = (value<<1)|SPI2_SDO;
+    value|=SPI2_portSDO;
     SPI2_CLK_LOW;
   }while((++i) & 0x07);
-  return value;
+  return value>>GPIO_SPI2_SDO;
 }
 
-void shiftInBuf(uint8_t *buf, uint16_t size) {
+static void shiftInBuf(uint8_t *buf, uint16_t size, uint16_t delay) {
   uint8_t i = 0;
   do{
     uint8_t value = 0;
@@ -88,10 +105,12 @@ void shiftInBuf(uint8_t *buf, uint16_t size) {
       SPI2_CLK_LOW;
     }while((++i) & 0x07);
     *buf++=value;
+    if (delay)
+      my_microsecond_delay(delay);
   }while(--size);
 }
 
-void shiftOutBuf(uint8_t *buf, uint16_t size) {
+static void shiftOutBuf(uint8_t *buf, uint16_t size) {
   uint8_t i = 0;
   do{
     uint8_t val = *buf++;
@@ -376,25 +395,19 @@ void SI4432_Fill(int s, int start)
 {
   SI4432_Sel = s;
   int sel = SI_nSEL[SI4432_Sel];
-#if 1
-  float t = setting.sweep_time - calc_min_sweep_time(); // Time to delay in mS
-  if (t < 0)
-    t = 0;
-  int ti = t * 1000 / 290.0;                         // Now in uS per point      if (t < 30000)
-  for (int i=start; i<sweep_points; ) {
-    SPI2_CLK_LOW;
+  float t = setting.sweep_time - calc_min_sweep_time();    // Time to delay in mS for all sweep
+  uint32_t ti = t < 0 ? 0 : t * 1000 / (sweep_points - 1); // Now in uS per point      if (t < 30000)
+  SPI2_CLK_LOW;
+  int i = 0;
+  do {
     palClearPad(GPIOC, sel);
     shiftOut( 0x26 );
-    age[i++]=(char)shiftIn();
+    age[i]=(char)shiftIn();
     palSetPad(GPIOC, sel);
+    if (++i >= sweep_points) break;
     if (ti)
       my_microsecond_delay(ti);
-  }
-#else
-  palClearPad(GPIOC, sel);
-  shiftInBuf((uint8_t*)age, sweep_points);
-  palSetPad(GPIOC, sel);
-#endif
+  } while(1);
   buf_index = start;
   buf_read = true;
 }
@@ -1055,3 +1068,5 @@ void ADF4351_prep_frequency(int channel, unsigned long freq, int drive)  // freq
 
 
 #endif
+
+#pragma GCC pop_options