HomeEnergyMeter/main/pcnt_functions.c

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "driver/ledc.h"
#include "driver/pcnt.h"
#include "esp_attr.h"
#include "esp_log.h"
#include "config.h"

#include "soc/dport_reg.h"

#ifdef CCFG_PCNT

// Example-code: https://github.com/espressif/esp-idf/blob/master/examples/peripherals/pcnt/pulse_count_event/main/pcnt_event_example_main.c

// PCNT unit counts incomming pulses by itself, but it can only count up to 32000, then an interrupt must poccur
// So an interrupt is comming every 32kWh (1 to multiple times per day)
// Counts interrupts that occus every 32K Pulses
// The counter register is 16 bit signed so we count to 32K before doing an interrupt
// This equals to 32kWH consumed energy (at 1000 pulses per kWh)
static uint32_t Counter_32K_Pulses = 0;

// A 32-bit unsigned (with resolution 1/1000 kWh) can hold 4294967kWh which is 214 years for us, so no problem

const int pcntUnit = PCNT_UNIT_0;

uint32_t getkWh() {

    volatile uint32_t firstRead, count, bigCounter;

    // Loop until we have two identical reads of the interrupt-updated 32K-counter
    // The 32K-counter is only updated maybe once per 24h, so should not be a problem
    do {
        firstRead = Counter_32K_Pulses;
        count = DPORT_REG_READ(0x3FF57060);
        bigCounter = Counter_32K_Pulses;
    } while( firstRead != bigCounter );

    return (bigCounter * 32000) + count;
}

static void IRAM_ATTR pcnt_example_intr_handler(void *arg)
{
    Counter_32K_Pulses++;
}

void init_pcnt_unit()
{
    /* Prepare configuration for the PCNT unit */
    pcnt_config_t pcnt_config = {
        // Set PCNT input signal and control GPIOs
        .pulse_gpio_num = PCNT_INPUT_SIG_IO,
        .ctrl_gpio_num = PCNT_INPUT_CTRL_IO,
        .channel = PCNT_CHANNEL_0,
        .unit = pcntUnit,
        // What to do on the positive / negative edge of pulse input?
        .pos_mode = PCNT_COUNT_INC,   // Count up on the positive edge
        .neg_mode = PCNT_COUNT_DIS,   // Keep the counter value on the negative edge
        // What to do when control input is low or high?
        .lctrl_mode = PCNT_MODE_REVERSE, // Reverse counting direction if low
        .hctrl_mode = PCNT_MODE_KEEP,    // Keep the primary counter mode if high
        // Set the maximum and minimum limit values to watch
        .counter_h_lim = 32000,
        .counter_l_lim = 0,
    };
    /* Initialize PCNT unit */
    pcnt_unit_config(&pcnt_config);

    // How to read a periphial-register:
    //uint32_t c = p_pcnt_obj->hal.dev.hw.conf_unit[unit];
    //printf("Reg: %08x\n",(uint32_t)DPORT_REG_READ(0x3FF57000));

    //The length of ignored pulses is provided in APB_CLK clock cycles by calling pcnt_set_filter_value().
    //The current filter setting may be checked with pcnt_get_filter_value().
    //The APB_CLK clock is running at 80 MHz.

    /* Configure and enable the input filter */
    pcnt_set_filter_value(pcntUnit, 1023); // APB_CLK=80MHz * 1023 is filtered out = 0,0127875mS (????)
    pcnt_filter_enable(pcntUnit);

    /* Enable int on high count limit */
    pcnt_event_enable(pcntUnit, PCNT_EVT_H_LIM);

    /* Initialize PCNT's counter */
    pcnt_counter_pause(pcntUnit);
    pcnt_counter_clear(pcntUnit);

    /* Install interrupt service and add isr callback handler */
    pcnt_isr_service_install(0);
    pcnt_isr_handler_add(pcntUnit, pcnt_example_intr_handler, (void *)pcntUnit);

    /* Everything is set up, now go to counting */
    pcnt_counter_resume(pcntUnit);
}

#else

void init_pcnt_unit() { }
uint32_t getkWh() { return 0; }

#endif