diff --git a/doc/InFrequencyShifting.xlsx b/doc/InFrequencyShifting.xlsx
new file mode 100644
index 0000000..09f5e83
Binary files /dev/null and b/doc/InFrequencyShifting.xlsx differ
diff --git a/my_src/inverter.c b/my_src/inverter.c
index 78f21df..6a11a87 100644
--- a/my_src/inverter.c
+++ b/my_src/inverter.c
@@ -21,10 +21,9 @@ extern TIM_HandleTypeDef htim5;
 
 
 #define NUM_OF_SINE_SLOT 30
+const uint32_t SLOT_WIDTH = 1500;
 const uint32_t FREQ_IN = 1E6;
 const float PI = 3.14159;
-float slotAngle = 180.0 / NUM_OF_SINE_SLOT;
-float sineValues[NUM_OF_SINE_SLOT];
 uint16_t IV[NUM_OF_SINE_SLOT];
 
 volatile uint32_t timer1Cnt;
@@ -49,8 +48,10 @@ volatile uint8_t phaseOrder[NUM_OF_TIMER];
 
 void inverterBegin() {
 	for (uint8_t i = 0; i < NUM_OF_SINE_SLOT; i++) {
+		float slotAngle = 180.0 / NUM_OF_SINE_SLOT;
 		float angle = i * slotAngle;
-		sineValues[i] = sinf(angle / 180 * PI);
+		float sineValues = sinf(angle / 180 * PI);
+		IV[i] = (uint16_t)(sineValues[i] * 0.9 * SLOT_WIDTH);
 	}
 
 	timerSupport[0].handle = &htim2;
@@ -62,6 +63,7 @@ void inverterBegin() {
 	timerSupport[0].channel = TIM_CHANNEL_1;
 	timerSupport[0].startMarkPort = LED0_GPIO_Port;
 	timerSupport[0].startMarkPin = LED0_Pin;
+	__HAL_TIM_SET_AUTORELOAD(timerSupport[0].handle, SLOT_WIDTH);
 
 	timerSupport[1].handle = &htim5;
 	timerSupport[1].running = false;
@@ -72,6 +74,7 @@ void inverterBegin() {
 	timerSupport[1].channel = TIM_CHANNEL_2;
 	timerSupport[1].startMarkPort = LED1_GPIO_Port;
 	timerSupport[1].startMarkPin = LED1_Pin;
+	__HAL_TIM_SET_AUTORELOAD(timerSupport[1].handle, SLOT_WIDTH);
 
 	timerSupport[2].handle = &htim4;
 	timerSupport[2].running = false;
@@ -82,15 +85,31 @@ void inverterBegin() {
 	timerSupport[2].channel = TIM_CHANNEL_1;
 	timerSupport[2].startMarkPort = LED2_GPIO_Port;
 	timerSupport[2].startMarkPin = LED2_Pin;
+	__HAL_TIM_SET_AUTORELOAD(timerSupport[2].handle, SLOT_WIDTH);
+
+	__HAL_TIM_SET_AUTORELOAD(&htim1, SLOT_WIDTH);
 }
 
-void inverterStart(uint8_t freqOut, direction_t direction) {
-	inverterStop();
-
-	uint16_t slotWidth = (FREQ_IN / (freqOut * NUM_OF_SINE_SLOT * 4));
-	for (uint8_t i = 0; i < NUM_OF_SINE_SLOT; i++) {
-		IV[i] = (uint16_t)(sineValues[i] * 0.9 * slotWidth);
+void inverterIncFrequency() {
+	uint16_t currPsc = htim1->Instance->PSC;
+	currPsc++;
+	htim1->Instance->PSC = currPsc;
+	for (uint8_t i = 0; i < NUM_OF_TIMER; i++) {
+		timerSupport[i].handle->Instance->PSC = currPsc;
 	}
+}
+
+void inverterDecFrequency() {
+	uint16_t currPsc = htim1->Instance->PSC;
+	currPsc--;
+	htim1->Instance->PSC = currPsc;
+	for (uint8_t i = 0; i < NUM_OF_TIMER; i++) {
+		timerSupport[i].handle->Instance->PSC = currPsc;
+	}
+}
+
+void inverterStart(direction_t direction) {
+	inverterStop();
 
 	if (direction == CLOCKWISE) {
 		phaseOrder[0] = 0;
@@ -107,11 +126,9 @@ void inverterStart(uint8_t freqOut, direction_t direction) {
 		timerSupport[i].slotCnt = 0;
 		timerSupport[i].running = false;
 		HAL_GPIO_WritePin(timerSupport[i].bridgePolarityPort, timerSupport[i].bridgePolarityPin, GPIO_PIN_RESET);
-		__HAL_TIM_SET_AUTORELOAD(timerSupport[i].handle, slotWidth);
 	}
 
 	timer1Cnt = 0;
-	__HAL_TIM_SET_AUTORELOAD(&htim1, slotWidth);
 	HAL_TIM_Base_Start_IT(&htim1);
 	__HAL_TIM_ENABLE_IT(&htim1, TIM_IT_UPDATE);
 }
diff --git a/my_src/inverter.h b/my_src/inverter.h
index dc29e28..f5f8b75 100644
--- a/my_src/inverter.h
+++ b/my_src/inverter.h
@@ -12,8 +12,10 @@
 typedef enum { CLOCKWISE, COUNTERCLOCKWISE } direction_t;
 
 void inverterBegin();
-void inverterStart(uint8_t freqOut, direction_t direction);
+void inverterStart(direction_t direction);
 void inverterStop();
+void inverterIncFrequency();
+void inverterDecFrequency();
 
 
 #endif /* INVERTER_H_ */
diff --git a/my_src/main2.c b/my_src/main2.c
index 9ed0f95..ce34e65 100644
--- a/my_src/main2.c
+++ b/my_src/main2.c
@@ -44,26 +44,13 @@ void my_errorHandler() {
 	HAL_GPIO_WritePin(ERROR_PIN_GPIO_Port, ERROR_PIN_Pin, GPIO_PIN_SET);
 }
 
-void testSwitchFrequency1(void *handle) {
-	inverterStart(100, CLOCKWISE);
-}
-void testSwitchFrequency2(void *handle) {
-	inverterStart(50, CLOCKWISE);
-}
-
-void testSwitchFrequency3(void *handle) {
-	static uint8_t f = 1;
-	inverterStart(f, CLOCKWISE);
-	f++;
+void testSwitchFrequency(void *handle) {
+	inverterIncFrequency();
 }
 void my_setup_2() {
 	inverterBegin();
-
-	inverterStart(1, CLOCKWISE);
-//	schAdd(testSwitchFrequency1, NULL, 5000, 0);
-//	schAdd(testSwitchFrequency2, NULL, 10000, 0);
-//	schAdd(testSwitchFrequency1, NULL, 15000, 0);
-	schAdd(testSwitchFrequency3, NULL, 0, 5000);
+	inverterStart(CLOCKWISE);
+	schAdd(testSwitchFrequency, NULL, 0, 5000);
 }