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#32 Addint the hc_sr04_stop function and making hc_sr04_on_set_trigge…
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…r public
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@trifuns
trifuns committed Jun 21, 2022
1 parent 7609738 commit 8f82166
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Showing 2 changed files with 36 additions and 38 deletions.
2 changes: 2 additions & 0 deletions bsp/hc_sr04.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@ typedef void(*timer_callback_t)(void);

void hc_sr04_init(us_callback_t us_callback, timer_callback_t timer_callback, NRF_TIMER_Type *us_on, NRF_TIMER_Type *us_read);
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);

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72 changes: 34 additions & 38 deletions bsp/nrf52833/hc_sr04.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,30 +28,24 @@
#define US_READ_CH_LoToHi 1UL
#define US_READ_CH_HiToLo 2UL

// Defines for setting up the trigger pulse width and frequency
#define PULSE_DURATION_MS 0.01
#define PULSE_OFFSET_MS 200
// Timer0 interrupt prioprity
#define TIMER0_INT_PRIORITY 2


//=========================== prototypes =======================================

void hc_sr04_gpio(void);
void hc_sr04_timers(void);
void hc_sr04_on_set_trigger(double duration_ms, double offset_ms);

//=========================== variables =======================================

typedef struct {

us_callback_t us_callback; // Function pointer, stores the callback to use in the GPIOTE_IRQn handler.
timer_callback_t timer_callback; // Function pointer, stores the callback to use in the GPIOTE_IRQn handler.

NRF_TIMER_Type *us_on_timer; // Pointer to the TIMER structure used for triggering US sensor
NRF_TIMER_Type *us_read_timer; // Pointer to the TIMER structure used for reading the range on the US sensor

volatile uint32_t us_reading; // Variable to store pulse duration of the US echo pin

} us_vars_t;

static us_vars_t us_vars;
Expand All @@ -78,22 +72,17 @@ void hc_sr04_init(us_callback_t us_callback, timer_callback_t timer_callback, NR

// initialize timers for US on and US read
hc_sr04_timers();

// initial timer settings for the trigger pulse
hc_sr04_on_set_trigger(PULSE_DURATION_MS, PULSE_OFFSET_MS);

}

/**
* @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 hc_sr04_start(void) {

void hc_sr04_start(void) {
// get endpoint addresses
uint32_t us_power_task_addr = (uint32_t)&NRF_GPIOTE->TASKS_OUT[US_ON_CH];
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 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;
Expand Down Expand Up @@ -129,16 +118,39 @@ void hc_sr04_start(void) {
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 disables the PPI channels to stop the US trigger and ranging.
*/
void hc_sr04_stop(void) {
// Stop the US ON timer
us_vars.us_on_timer->TASKS_STOP = (TIMER_TASKS_STOP_TASKS_STOP_Trigger << TIMER_TASKS_STOP_TASKS_STOP_Pos);

// 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 private and it sets the compare registers for US trigger timer
*/
void hc_sr04_on_set_trigger(double duration_ms, double offset_ms) {

// Set compare values for US on
us_vars.us_on_timer->CC[0] = offset_ms * 1000; // first compare register for setting the offset and start of the pulse
us_vars.us_on_timer->CC[1] = (offset_ms + duration_ms) * 1000; // second compare for pulse duration

}

/**
* @brief This function is public and it enables HFCLK
*/
void hfclk_init(void) {

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.

}

//=========================== private ==========================================
Expand All @@ -147,7 +159,6 @@ void hfclk_init(void) {
* @brief Function for initializing GPIOTE for US trigger and US echo signals.
*/
void hc_sr04_gpio(void) {

//configure US_ON as an output PIN which toggles
NRF_GPIOTE->CONFIG[US_ON_CH] = (GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |
(US_ON_PIN << GPIOTE_CONFIG_PSEL_Pos) |
Expand Down Expand Up @@ -175,14 +186,12 @@ void hc_sr04_gpio(void) {

NVIC_ClearPendingIRQ(GPIOTE_IRQn); // Clear the flag for any pending radio interrupt
NVIC_EnableIRQ(GPIOTE_IRQn);

}

/**
* @brief This function is private and it sets up the Bitmode and Prescaler for US trigger and US echo timers
*/
void hc_sr04_timers(void) {

// configure the Timer for US on
us_vars.us_on_timer->BITMODE = TIMER_BITMODE_BITMODE_32Bit;
us_vars.us_on_timer->PRESCALER = 4UL;
Expand All @@ -191,33 +200,20 @@ void hc_sr04_timers(void) {
us_vars.us_read_timer->BITMODE = TIMER_BITMODE_BITMODE_32Bit;
us_vars.us_read_timer->PRESCALER = 4UL;

}

/**
* @brief This function is private and it sets the compare registers for US trigger timer
*/
void hc_sr04_on_set_trigger(double duration_ms, double offset_ms) {

// Set compare values for US on
us_vars.us_on_timer->CC[0] = offset_ms * 1000; // first compare register for setting the offset and start of the pulse
us_vars.us_on_timer->CC[1] = (offset_ms + duration_ms) * 1000; // second compare for pulse duration

// set Timer to clear after the trigger pulse
// set ON Timer to clear after the trigger pulse
us_vars.us_on_timer->SHORTS = (TIMER_SHORTS_COMPARE1_CLEAR_Enabled << TIMER_SHORTS_COMPARE1_CLEAR_Pos);

// Configure the Interruptions
// Configure the Interruptions for the Timer0 used as the ON US sensor timer
NVIC_DisableIRQ(TIMER0_IRQn);

// enable interrupts on Compare 1
us_vars.us_on_timer->INTENSET = (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos);

NVIC_SetPriority(TIMER0_IRQn, TIMER0_INT_PRIORITY);

NVIC_ClearPendingIRQ(TIMER0_IRQn); // Clear the flag for any pending radio interrupt

// enable interupts
NVIC_EnableIRQ(TIMER0_IRQn);

}

//=========================== interrupt handlers ==============================
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