141 lines
4.8 KiB
C
141 lines
4.8 KiB
C
#include <zephyr/kernel.h>
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#include <zephyr/device.h>
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#include <nrf_gpio.h>
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#include <nrf_timer.h>
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#define TST_CLK_PIN 17 //this is led 0 pin on nrf52-dk
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#define FREQ_MEASURE_PIN 11
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void gpio_clock_8m(uint32_t pin_number)
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{
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NRF_TIMER0->PRESCALER = 0; // 16MHz
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NRF_TIMER0->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Msk;
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NRF_TIMER0->CC[0] = 3; //1 for 16/2=8MHz for, 2 for 8/2=4MHz, 4 for 4/2=2MHz etc..
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NRF_TIMER0->BITMODE = (TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos);
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//using config [1] since [0]
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NRF_GPIOTE->CONFIG[1] = GPIOTE_CONFIG_MODE_Task | (pin_number << GPIOTE_CONFIG_PSEL_Pos) |
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(GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos);
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/*Connect TIMER event to GPIOTE out task*/
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NRF_PPI->CHEN |= 1 << 3;
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*(&(NRF_PPI->CH3_EEP)) = (uint32_t) &NRF_TIMER0->EVENTS_COMPARE[0];
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*(&(NRF_PPI->CH3_TEP)) = (uint32_t) &NRF_GPIOTE->TASKS_OUT[1];
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NRF_PPI->CHENSET |= 1 << 3;
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/*Starts clock signal*/
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NRF_TIMER0->TASKS_START = 1;
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}
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static void timer_init() //gate timer
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{
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NRF_TIMER1->TASKS_STOP = 1; //trigger stop
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NRF_TIMER1->MODE = TIMER_MODE_MODE_Timer; //mode timer
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NRF_TIMER1->PRESCALER = 8; // Fhck / 2^8
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//total gate time of timer 62500 - 1s
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NRF_TIMER1->CC[0] = 62501; //end gate count
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NRF_TIMER1->CC[1] = 1; //start gate count. don't start at 0 to no start on clear.
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NRF_TIMER1->BITMODE = (TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos);
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NRF_TIMER1->TASKS_CLEAR = 1; //trigger zero timer
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NRF_TIMER1->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos); //interrupt on end gate count
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NRF_TIMER1->EVENTS_COMPARE[0] = 0; //rest event flag for gate end
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NRF_TIMER1->EVENTS_COMPARE[1] = 0; //rest event flag for gate start
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}
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static void counter_init() //actual counter
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{
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NRF_TIMER2->TASKS_STOP = 1; //trigger stop
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NRF_TIMER2->MODE = TIMER_MODE_MODE_Counter; //counter
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NRF_TIMER2->BITMODE = (TIMER_BITMODE_BITMODE_24Bit << TIMER_BITMODE_BITMODE_Pos);
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NRF_TIMER2->TASKS_CLEAR = 1; //trigger zero counter
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NRF_TIMER2->EVENTS_COMPARE[0] = 0; //reset event for compare
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}
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//counter input pin setting
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static void gpiote_init(uint32_t pin)
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{
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NRF_GPIOTE->CONFIG[0] = 0x01 << 0; // MODE: Event
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NRF_GPIOTE->CONFIG[0] |= pin << 8; // Pin number
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NRF_GPIOTE->CONFIG[0] |= GPIOTE_CONFIG_POLARITY_LoToHi << 16; // Event rising edge
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}
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//hardware trigger: stop of counter on event of end timer1 gate
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static void ppi_timer_stop_counter_init()
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{
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NRF_PPI->CHEN |= 1 << 2; //channel
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*(&(NRF_PPI->CH2_EEP)) = (uint32_t)&NRF_TIMER1->EVENTS_COMPARE[0]; //attach end gate event
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*(&(NRF_PPI->CH2_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_STOP; //to counter stop trigger
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NRF_PPI->CHENSET |= 1 << 2; //set channel
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}
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//hardware trigger: start of counter on event of begin timer1 (gate) event.gate
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static void ppi_timer_start_counter_init()
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{
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NRF_PPI->CHEN |= 1 << 4;// channel
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*(&(NRF_PPI->CH4_EEP)) = (uint32_t)&NRF_TIMER1->EVENTS_COMPARE[1]; //attach gate start event
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*(&(NRF_PPI->CH4_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_START; //to counter start trigger
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NRF_PPI->CHENSET |= 1 << 4;
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}
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static void ppi_gpiote_counter_init()
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//hardware attachment for the gpiote that was selected above
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{
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NRF_PPI->CHEN |= 1 << 1;
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*(&(NRF_PPI->CH1_EEP)) = (uint32_t)&NRF_GPIOTE->EVENTS_IN[0]; //attach pin change
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*(&(NRF_PPI->CH1_TEP)) = (uint32_t)&NRF_TIMER2->TASKS_COUNT;//to one count
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NRF_PPI->CHENSET |= 1 << 1;
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}
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//gate end interrupt handler. Count is done at hardware and percice interrupt execution isnt critical
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void TIMER1_IRQHandler(void)
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{
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if (NRF_TIMER1->EVENTS_COMPARE[0] != 0) //end gate event
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{
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NRF_TIMER1->EVENTS_COMPARE[0] = 0; //reset end gate flag
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NRF_TIMER1->EVENTS_COMPARE[1] = 0; //reset start gate flag
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NRF_TIMER2->TASKS_CAPTURE[0] = 1; //trigger get counter value
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printk("cc: %dHz\n", NRF_TIMER2->CC[0]); //report to serial console
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NRF_TIMER1->TASKS_CLEAR = 1; //reset timer
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NRF_TIMER2->TASKS_CLEAR = 1; //reset counter
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NRF_TIMER1->TASKS_START = 1; //start next count gate
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}
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}
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int main(void)
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{
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NVIC_EnableIRQ(TIMER1_IRQn); //enable timer1 interrupt
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IRQ_DIRECT_CONNECT(TIMER1_IRQn, 3, TIMER1_IRQHandler, 0); //link interrupt flag to handler
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NVIC_SetPriority(TIMER1_IRQn, 3); //set interrupt execution priority
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struct device *dev;//port container for gpio management
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dev = device_get_binding("GPIO_14"); //button SW1
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/**/
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//nrf_gpio_cfg(dev, FREQ_MEASURE_PIN, NRF_GPIO_DIR_INPUT|GPIO_ACTIVE_HIGH|GPIO_PULL_DOWN); //p0.11 freq in
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nrf_gpio_cfg_input(14, NRF_GPIO_PIN_PULLUP);
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//init freq count hardware
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counter_init();
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timer_init();
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gpiote_init(FREQ_MEASURE_PIN);
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ppi_gpiote_counter_init();
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ppi_timer_stop_counter_init();
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ppi_timer_start_counter_init();
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//test clock hardware
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gpio_clock_8m(TST_CLK_PIN);
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//start freq count task
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NRF_TIMER1->TASKS_START = 1;
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while (1) {
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//manage loop
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}
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}
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