nRF52810_preliminary_software_tests/main.c

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/uart.h>

#include <nrf_gpio.h>
#include <nrf_timer.h>

#define TST_CLK_PIN 17 //this is led 0 pin on nrf52-dk
#define FREQ_MEASURE_PIN 11

const struct device *uart0 = DEVICE_DT_GET(DT_NODELABEL(uart0));


struct uart_config uart_cfg = {
	.baudrate = 9600,
	.parity = UART_CFG_PARITY_NONE,
	.stop_bits = UART_CFG_STOP_BITS_1,
	.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,
	.data_bits = UART_CFG_DATA_BITS_8,
};

void send_str(const struct device *uart, char *str)
{
	int msg_len = strlen(str);

	for (int i = 0; i < msg_len; i++) {
		uart_poll_out(uart, str[i]);
	}

	printk("Device %s sent: \"%s\"\n", uart->name, str);
}

void recv_str(const struct device *uart, char *str)
{
	char *head = str;
	char c;

	while (!uart_poll_in(uart, &c)) {
		*head++ = c;
	}
	*head = '\0';

	printk("Device %s received: \"%s\"\n", uart->name, str);
}

void gpio_clock_8m(uint32_t pin_number)
{
    
    NRF_TIMER0->PRESCALER = 0; // 16MHz
    NRF_TIMER0->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Msk;
    NRF_TIMER0->CC[0] = 3; //1 for 16/2=8MHz for, 2 for 8/2=4MHz, 4 for 4/2=2MHz etc..
	NRF_TIMER0->BITMODE = (TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos);	
	//using config [1] since [0]
    NRF_GPIOTE->CONFIG[1] = GPIOTE_CONFIG_MODE_Task | (pin_number << GPIOTE_CONFIG_PSEL_Pos) |
                            (GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos);

    /*Connect TIMER event to GPIOTE out task*/
	NRF_PPI->CHEN |= 1 << 3;
    *(&(NRF_PPI->CH3_EEP)) = (uint32_t) &NRF_TIMER0->EVENTS_COMPARE[0];
    *(&(NRF_PPI->CH3_TEP)) = (uint32_t) &NRF_GPIOTE->TASKS_OUT[1];
    NRF_PPI->CHENSET |= 1 << 3;

    /*Starts clock signal*/
    NRF_TIMER0->TASKS_START = 1;
}

static void timer_init() //gate timer
{
	NRF_TIMER1->TASKS_STOP = 1; //trigger stop
	NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer; //mode timer
	NRF_TIMER1->PRESCALER = 8;	// Fhck / 2^8 
	//total gate time of timer 62500 - 1s
	NRF_TIMER1->CC[0] = 62501;	//end gate count
	NRF_TIMER1->CC[1] = 1;	//start gate count. don't start at 0 to no start on clear.
	
	NRF_TIMER1->BITMODE = (TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos);	
	
	NRF_TIMER1->TASKS_CLEAR = 1; //trigger zero timer
	NRF_TIMER1->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos); //interrupt on end gate count
	
	NRF_TIMER1->EVENTS_COMPARE[0] = 0; //rest event flag for gate end
	NRF_TIMER1->EVENTS_COMPARE[1] = 0; //rest event flag for gate start
}

static void counter_init() //actual counter
{
	NRF_TIMER2->TASKS_STOP = 1;	//trigger stop
	NRF_TIMER2->MODE = TIMER_MODE_MODE_Counter; //counter
	NRF_TIMER2->BITMODE = (TIMER_BITMODE_BITMODE_24Bit << TIMER_BITMODE_BITMODE_Pos);
	NRF_TIMER2->TASKS_CLEAR = 1; //trigger zero counter
	NRF_TIMER2->EVENTS_COMPARE[0] = 0; //reset event for compare
}

//counter input pin setting
static void gpiote_init(uint32_t pin)
{
	NRF_GPIOTE->CONFIG[0] 	= 	0x01 << 0; 								// MODE: Event
	NRF_GPIOTE->CONFIG[0] 	|= 	pin << 8;								// Pin number
	NRF_GPIOTE->CONFIG[0] 	|= 	GPIOTE_CONFIG_POLARITY_LoToHi	<< 16;		// Event rising edge 	
}

//hardware trigger: stop of counter on event of end timer1 gate
static void ppi_timer_stop_counter_init()
{
	NRF_PPI->CHEN |= 1 << 2; //channel
	*(&(NRF_PPI->CH2_EEP)) = (uint32_t)&NRF_TIMER1->EVENTS_COMPARE[0]; //attach end gate event
	*(&(NRF_PPI->CH2_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_STOP; //to counter stop trigger
	NRF_PPI->CHENSET |= 1 << 2; //set channel
}

//hardware trigger: start of counter on event of begin timer1 (gate) event.gate
static void ppi_timer_start_counter_init()
{
	NRF_PPI->CHEN |= 1 << 4;// channel
	*(&(NRF_PPI->CH4_EEP)) = (uint32_t)&NRF_TIMER1->EVENTS_COMPARE[1]; //attach gate start event
	*(&(NRF_PPI->CH4_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_START; //to counter start trigger
	NRF_PPI->CHENSET |= 1 << 4;
}


static void ppi_gpiote_counter_init()
//hardware attachment for the gpiote that was selected above
{
	NRF_PPI->CHEN |= 1 << 1;
	*(&(NRF_PPI->CH1_EEP)) = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0]; //attach pin change
	*(&(NRF_PPI->CH1_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_COUNT;//to one count
	NRF_PPI->CHENSET |= 1 << 1;
}

//gate end interrupt handler. Count is done at hardware and percice interrupt execution isnt critical
void TIMER1_IRQHandler(void) 
{
	if (NRF_TIMER1->EVENTS_COMPARE[0] != 0) //end gate event
	{
		NRF_TIMER1->EVENTS_COMPARE[0] = 0; //reset end gate flag
		NRF_TIMER1->EVENTS_COMPARE[1] = 0; //reset start gate flag
		NRF_TIMER2->TASKS_CAPTURE[0] = 1; //trigger get counter value
				
		printk("cc: %dHz\n", NRF_TIMER2->CC[0]); //report to serial console
      	
		NRF_TIMER1->TASKS_CLEAR = 1; //reset timer
		NRF_TIMER2->TASKS_CLEAR = 1; //reset counter
						
		NRF_TIMER1->TASKS_START = 1; //start next count gate		
    }
}

int main(void)
{
	char send_buf[64];

	printk("Hellowold 1!");
	/*rc = uart_configure(uart0, &uart_cfg);
	if (rc) {
		printk("Could not configure device %s", uart0->name);
	}*/

	snprintf(send_buf, 64, "Helloworld 2");
	send_str(uart0, send_buf);


	NVIC_EnableIRQ(TIMER1_IRQn); //enable timer1 interrupt
	IRQ_DIRECT_CONNECT(TIMER1_IRQn, 3, TIMER1_IRQHandler, 0); //link interrupt flag to handler
    NVIC_SetPriority(TIMER1_IRQn, 3); //set interrupt execution priority

	struct device *dev;//port container for gpio management
	dev = device_get_binding("GPIO_14"); //button SW1
	/**/
	//nrf_gpio_cfg(dev, FREQ_MEASURE_PIN, NRF_GPIO_DIR_INPUT|GPIO_ACTIVE_HIGH|GPIO_PULL_DOWN); //p0.11 freq in
	nrf_gpio_cfg_input(14, NRF_GPIO_PIN_PULLUP);

	//init freq count hardware
	counter_init();
	timer_init();
	gpiote_init(FREQ_MEASURE_PIN);
	ppi_gpiote_counter_init();
	ppi_timer_stop_counter_init();
	ppi_timer_start_counter_init();

	//test clock hardware
	gpio_clock_8m(TST_CLK_PIN);

	//start freq count task
	NRF_TIMER1->TASKS_START = 1;
	while (1) {
				//manage loop
	}
}