First commit

drivers/timer_count/timer_count.c

@@ -0,0 +1,153 @@
+#include "timer_count.h"
+
+#define MEAS_PIN 11
+#define OSCILLATOR_INIT_DELAY_MS 5
+#define USER_NODE DT_PATH(zephyr_user)
+static const struct gpio_dt_spec hum_en = GPIO_DT_SPEC_GET(USER_NODE, hum_en_gpios);
+
+uint32_t count = 0;
+uint32_t timer_status = 0;
+
+void configure_clock_pin(uint32_t pin_number){
+    nrf_gpio_cfg(
+        pin_number,
+        NRF_GPIO_PIN_DIR_INPUT,
+        NRF_GPIO_PIN_INPUT_CONNECT,
+        NRF_GPIO_PIN_PULLUP,
+        NRF_GPIO_PIN_S0S1,
+        NRF_GPIO_PIN_NOSENSE);
+		*(volatile uint32_t *)(NRF_GPIOTE_BASE + 0x600 + (4 * pin_number)) = 1;
+}
+
+void timer_init() //gate timer
+{
+	NRF_TIMER1->TASKS_STOP = 1; //trigger stop
+	NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer; //mode timer
+	NRF_TIMER1->PRESCALER = 4;	// Fhck / 2^8 -1MHz
+	//total gate time of timer 10000 - 100mS
+	NRF_TIMER1->CC[0] = 50000;	//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_32Bit << 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) //Pin must be in port 0
+{
+	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
+		count = NRF_TIMER2->CC[0];
+      	
+		NRF_TIMER1->TASKS_CLEAR = 1; //reset timer
+		NRF_TIMER2->TASKS_CLEAR = 1; //reset counter
+
+        timer_status = STATE_FINISHED;
+		NRF_TIMER1->TASKS_STOP = 1; //stop
+		gpio_pin_set_dt(&hum_en, 0);
+		//NRF_TIMER1->TASKS_START = 1; //start next count gate		
+    }
+}
+
+void configure_measurement()
+{
+
+	int ret = 0;
+	NVIC_ClearPendingIRQ(TIMER1_IRQn);
+	NVIC_EnableIRQ(TIMER1_IRQn); //enable timer1 interrupt
+	IRQ_CONNECT(TIMER1_IRQn, 5, TIMER1_IRQHandler, 0, 0); //link interrupt flag to handler
+
+	if (!device_is_ready(hum_en.port)) {
+        printk("hum_en device not ready\n");
+        return;
+    }
+	    ret = gpio_pin_configure_dt(&hum_en, GPIO_OUTPUT_ACTIVE); if (ret < 0)
+    {
+        printk("Failed to configure hum_en\n");
+        return;
+    }
+
+	configure_clock_pin(MEAS_PIN);
+
+	counter_init();
+	timer_init();
+	gpiote_init(MEAS_PIN);
+	ppi_gpiote_counter_init();
+	ppi_timer_stop_counter_init();
+	ppi_timer_start_counter_init();
+
+}
+
+void make_measurement()
+{
+	if( timer_status == STATE_RUNNING) {
+		//manage error here
+		return;
+	}
+
+    gpio_pin_set_dt(&hum_en, 1);
+    k_sleep(K_MSEC(OSCILLATOR_INIT_DELAY_MS));
+
+    timer_status = STATE_RUNNING;
+	NRF_TIMER1->TASKS_START = 1;
+}
+
+uint32_t read_measurement(){
+    if(timer_status != STATE_FINISHED) {
+        return -timer_status;
+    }
+    else{
+        return count;
+    }
+}

drivers/timer_count/timer_count.h

@@ -0,0 +1,22 @@
+#ifndef TIMER_COUNT_H
+#define TIMER_COUNT_H
+
+#include <stdint.h>
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/sys/printk.h>
+#include <zephyr/drivers/gpio.h>
+
+#include <hal/nrf_gpio.h>
+
+#define STATE_DISABLED 0
+#define STATE_RUNNING 1
+#define STATE_FINISHED 2
+
+void configure_clock_pin(uint32_t);
+void TIMER1_IRQHandler(void);
+void configure_measurement();
+void make_measurement();
+uint32_t read_measurement();
+
+# endif