diff --git a/bsp/hc_sr04.h b/bsp/hc_sr04.h
index a4ac46b00..99ae3b906 100644
--- a/bsp/hc_sr04.h
+++ b/bsp/hc_sr04.h
@@ -28,6 +28,7 @@ void hc_sr04_init(us_callback_t us_callback, timer_callback_t timer_callback, NR
 void hc_sr04_start(void);
 void hc_sr04_stop(void);
 void hc_sr04_on_set_trigger(double duration_ms, double offset_ms);
+
 void hfclk_init(void);
 
-#endif
+#endif
\ No newline at end of file
diff --git a/bsp/nrf52833/hc_sr04.c b/bsp/nrf52833/hc_sr04.c
index e8d72a59f..54fd9181b 100644
--- a/bsp/nrf52833/hc_sr04.c
+++ b/bsp/nrf52833/hc_sr04.c
@@ -133,7 +133,7 @@ void hc_sr04_stop(void) {
 }
 
 /**
- * @brief This function is private and it sets the compare registers for US trigger timer
+ * @brief This function is public and it sets the compare registers for US trigger timer
  */
 void hc_sr04_on_set_trigger(double duration_ms, double offset_ms) {
 
@@ -214,78 +214,6 @@ void hc_sr04_timers(void) {
     NVIC_ClearPendingIRQ(TIMER0_IRQn);    // Clear the flag for any pending radio interrupt
     // enable interupts
     NVIC_EnableIRQ(TIMER0_IRQn);
-    
-    // start the US trigger timer
-    us_vars.us_on_timer->TASKS_START = (TIMER_TASKS_START_TASKS_START_Trigger << TIMER_TASKS_START_TASKS_START_Pos);
-
-}
-
-/**
- * @brief This function is public and it sets the PPI channels to allow the US trigger and US echo. Ranging starts by calling this function
- */
-void us_start(void) {
-    
-    // get endpoint addresses
-    uint32_t us_power_task_addr              = (uint32_t)&NRF_GPIOTE->TASKS_OUT[US_ON_CH];
-
-    uint32_t us_read_event_low_high_addr     = (uint32_t)&NRF_GPIOTE->EVENTS_IN[US_READ_CH_LoToHi];
-    uint32_t us_read_event_high_low_addr     = (uint32_t)&NRF_GPIOTE->EVENTS_IN[US_READ_CH_HiToLo];
-
-    uint32_t timer3_task_start_addr         = (uint32_t)&us_vars.us_read_timer->TASKS_START;
-    uint32_t timer3_task_clear_addr         = (uint32_t)&us_vars.us_read_timer->TASKS_CLEAR;
-    uint32_t timer3_task_stop_addr          = (uint32_t)&us_vars.us_read_timer->TASKS_STOP;
-    uint32_t timer3_task_capture_addr       = (uint32_t)&us_vars.us_read_timer->TASKS_CAPTURE[0];
-    
-    uint32_t timer2_events_compare_0_addr   = (uint32_t)&us_vars.us_on_timer->EVENTS_COMPARE[0];
-    uint32_t timer2_events_compare_1_addr   = (uint32_t)&us_vars.us_on_timer->EVENTS_COMPARE[1];
-
-
-    // set endpoints
-    NRF_PPI->CH[0].EEP       = timer2_events_compare_0_addr;
-    NRF_PPI->CH[0].TEP       = us_power_task_addr;
-
-    NRF_PPI->CH[1].EEP       = timer2_events_compare_1_addr;
-    NRF_PPI->CH[1].TEP       = us_power_task_addr;
-
-    NRF_PPI->CH[2].EEP       = us_read_event_low_high_addr;
-    NRF_PPI->CH[2].TEP       = timer3_task_clear_addr;
-    NRF_PPI->FORK[2].TEP     = timer3_task_start_addr;
-
-    NRF_PPI->CH[3].EEP       = us_read_event_high_low_addr;
-    NRF_PPI->CH[3].TEP       = timer3_task_capture_addr;
-    NRF_PPI->FORK[3].TEP     = timer3_task_stop_addr;
-
-    // enable channels
-    NRF_PPI->CHENSET = (PPI_CHENSET_CH0_Enabled << PPI_CHENSET_CH0_Pos) | 
-                       (PPI_CHENSET_CH1_Enabled << PPI_CHENSET_CH1_Pos) |
-                       (PPI_CHENSET_CH2_Enabled << PPI_CHENSET_CH2_Pos) |
-                       (PPI_CHENSET_CH3_Enabled << PPI_CHENSET_CH3_Pos);
-                                                      
-}
-
-/**
- * @brief This function is public and it disables the PPI channels to stop the US trigger and ranging.
- */
-void us_stop(void) {
-
-    // disable PPI channels for US ranging
-    NRF_PPI->CHENCLR = (PPI_CHENCLR_CH0_Enabled << PPI_CHENSET_CH0_Pos) | 
-                       (PPI_CHENCLR_CH1_Enabled << PPI_CHENSET_CH1_Pos) |
-                       (PPI_CHENCLR_CH2_Enabled << PPI_CHENSET_CH2_Pos) |
-                       (PPI_CHENCLR_CH3_Enabled << PPI_CHENSET_CH3_Pos);
-
-}
-
-/**
- * @brief This function is public and it enables HFCLK
- */
-void hfclk_init(void) {
-    
-    // Configure the external High-frequency Clock. (Needed for correct operation)
-    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0x00;    // Clear the flag
-    NRF_CLOCK->TASKS_HFCLKSTART    = 0x01;    // Start the clock
-    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) {;} // Wait for the clock to actually start.
-
 }
 
 //=========================== interrupt handlers ==============================
@@ -320,5 +248,4 @@ void TIMER0_IRQHandler(void){
         // Call callback defined by user.
         (*us_vars.timer_callback)();      
     }
-}
-
+}
\ No newline at end of file