circuitpython/ports/atmel-samd/common-hal/rtc/RTC.c
Noralf Trønnes 681399f8db atmel-samd: RTC: Improve precision when setting datetime
The prescaler is not reset when setting the counter so we can be off by
as much as 1023/1024 seconds. Fix this by resetting the RTC module.
2018-05-01 21:35:24 -04:00

105 lines
3.5 KiB
C

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Noralf Trønnes
*
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* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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*/
#include <stdlib.h>
#include <peripheral_clk_config.h>
#include <hal_init.h>
#include <hpl_gclk_base.h>
#include <hpl_pm_base.h>
#include <hal_calendar.h>
#include "py/obj.h"
#include "py/runtime.h"
#include "lib/timeutils/timeutils.h"
#include "shared-bindings/rtc/__init__.h"
static struct calendar_descriptor calendar;
void rtc_init(void) {
#ifdef SAMD21
_gclk_enable_channel(RTC_GCLK_ID, CONF_GCLK_RTC_SRC);
#endif
#ifdef SAMD51
hri_mclk_set_APBAMASK_RTC_bit(MCLK);
#endif
calendar_init(&calendar, RTC);
calendar_set_baseyear(&calendar, 2000);
calendar_enable(&calendar);
}
void common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
struct calendar_date_time datetime;
calendar_get_date_time(&calendar, &datetime);
tm->tm_year = datetime.date.year;
tm->tm_mon = datetime.date.month;
tm->tm_mday = datetime.date.day;
tm->tm_hour = datetime.time.hour;
tm->tm_min = datetime.time.min;
tm->tm_sec = datetime.time.sec;
}
void common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
// Reset prescaler to increase initial precision. Otherwise we can be up to 1 second off already.
uint32_t freqcorr = hri_rtcmode0_read_FREQCORR_reg(calendar.device.hw);
calendar_deinit(&calendar);
rtc_init();
hri_rtcmode0_write_FREQCORR_reg(calendar.device.hw, freqcorr);
struct calendar_date date = {
.year = tm->tm_year,
.month = tm->tm_mon,
.day = tm->tm_mday,
};
calendar_set_date(&calendar, &date);
struct calendar_time time = {
.hour = tm->tm_hour,
.min = tm->tm_min,
.sec = tm->tm_sec,
};
calendar_set_time(&calendar, &time);
}
// A positive value speeds up the clock by removing clock cycles.
int common_hal_rtc_get_calibration(void) {
int calibration = hri_rtcmode0_read_FREQCORR_VALUE_bf(calendar.device.hw);
if (!hri_rtcmode0_get_FREQCORR_SIGN_bit(calendar.device.hw))
calibration = -calibration;
return calibration;
}
void common_hal_rtc_set_calibration(int calibration) {
if (calibration > 127 || calibration < -127)
mp_raise_ValueError("calibration value out of range +/-127");
hri_rtcmode0_write_FREQCORR_SIGN_bit(calendar.device.hw, calibration < 0 ? 0 : 1);
hri_rtcmode0_write_FREQCORR_VALUE_bf(calendar.device.hw, abs(calibration));
}