about MS5611 problem

#include <AP_Common.h>
#include <AP_Progmem.h>
#include <AP_Param.h>
#include <AP_Math.h>
#include <AP_HAL.h>
#include <AP_Buffer.h>
#include <Filter.h>
#include <AP_Baro.h>

#include <AP_HAL_AVR.h>
const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;

#if CONFIG_HAL_BOARD == HAL_BOARD_APM2

AP_Baro_MS5611 baro(&AP_Baro_MS5611::spi);
static uint32_t timer;

void setup()
{
    hal.console->println("APM2 MS5611 Barometer library test");

    hal.scheduler->delay(1000);

    /* What's this for? */
    hal.gpio->pinMode(63, HAL_GPIO_OUTPUT);
    hal.gpio->write(63, 1);
    
    baro.init();
    baro.calibrate();

    timer = hal.scheduler->micros();
}

void loop()
{
    if((hal.scheduler->micros() - timer) > 100000UL) {
        timer = hal.scheduler->micros();
        baro.read();
        uint32_t read_time = hal.scheduler->micros() - timer;
        if (!baro.healthy) {
            hal.console->println("not healthy");
            return;
        }
        hal.console->print("Pressure:");
        hal.console->print(baro.get_pressure());
        hal.console->print(" Temperature:");
        hal.console->print(baro.get_temperature());
        hal.console->print(" Altitude:");
        hal.console->print(baro.get_altitude());
        hal.console->printf(" climb=%.2f t=%u samples=%u",
                      baro.get_climb_rate(),
                      (unsigned)read_time,
                      (unsigned)baro.get_pressure_samples());
        hal.console->println();
    }
}

#else // Non-APM2
#warning AP_Baro_MS5611_test built as stub for APM1
void setup () {}
void loop () {}
#endif

AP_HAL_MAIN();

what is this function => hal.scheduler->delay(1000);?
why should need to use this ?

where can I find the reading data’s pattern ?
how long will it read the data?