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dhalbertdhalbert
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Merge pull request adafruit#11491 from tannewt/zephyr_rtc
Implement RTC on Zephyr
2 parents eec31fe + 3156883 commit 35210c2

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‎ports/zephyr-cp/boards/st/stm32wba65i_dk1/board.overlay‎

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status = "okay";
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};
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/* The board's &rtc node is already status-okay in the upstream devicetree, so
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* alias it so the rtc module picks it up like other RTC boards do. */
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/ {
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aliases {
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rtc = &rtc;
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};
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};
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/* The USB device controller (zephyr_udc0, including the OTG HS PHY and the
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* HSE/VOS clocking it needs) and the joystick-selector boot button are
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* defined in the mcuboot fork's dts/st/stm32wba65i_dk1.dtsi, which sysbuild

‎ports/zephyr-cp/common-hal/rtc/RTC.c‎

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// This file is part of the CircuitPython project: https://circuitpython.org
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//
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// SPDX-FileCopyrightText: Copyright (c) 2026 Scott Shawcroft for Adafruit Industries
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//
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// SPDX-License-Identifier: MIT
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#include <errno.h>
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#include "py/obj.h"
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#include "py/runtime.h"
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#include "shared/timeutils/timeutils.h"
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#include "shared-bindings/rtc/RTC.h"
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#include "common-hal/rtc/RTC.h"
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#include "bindings/zephyr_kernel/__init__.h"
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#include <zephyr/devicetree.h>
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#include <zephyr/device.h>
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#include <zephyr/drivers/rtc.h>
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// The RTC driver already initializes its device at Zephyr boot time, so there
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// is nothing for the port to start up: time is simply read from and written
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// to the devicetree `rtc` device.
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static const struct device *const rtc_dev = DEVICE_DT_GET(DT_ALIAS(rtc));
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// Zephyr stores calibration in parts per billion. CircuitPython's calibration
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// unit is approximately one part per million.
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#define CALIBRATION_PPM_TO_ZEPHYR (1000)
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void common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
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struct rtc_time zephyr_tm;
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int ret = rtc_get_time(rtc_dev, &zephyr_tm);
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if (ret == -ENODATA) {
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// The RTC has never been set (no battery-backed hardware and no
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// seeded time). Report the start of the CircuitPython epoch,
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// 2000-01-01, instead of failing; users set it with
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// rtc.RTC().datetime.
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timeutils_seconds_since_2000_to_struct_time(0, tm);
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return;
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}
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CHECK_ZEPHYR_RESULT(ret);
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tm->tm_year = zephyr_tm.tm_year + 1900;
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tm->tm_mon = zephyr_tm.tm_mon + 1;
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tm->tm_mday = zephyr_tm.tm_mday;
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tm->tm_hour = zephyr_tm.tm_hour;
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tm->tm_min = zephyr_tm.tm_min;
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tm->tm_sec = zephyr_tm.tm_sec;
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// tm_wday and tm_yday are filled in by struct_time_from_tm.
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}
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void common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
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struct rtc_time zephyr_tm = {
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.tm_year = tm->tm_year - 1900,
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.tm_mon = tm->tm_mon - 1,
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.tm_mday = tm->tm_mday,
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.tm_hour = tm->tm_hour,
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.tm_min = tm->tm_min,
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.tm_sec = tm->tm_sec,
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};
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CHECK_ZEPHYR_RESULT(rtc_set_time(rtc_dev, &zephyr_tm));
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}
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int common_hal_rtc_get_calibration(void) {
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#ifdef CONFIG_RTC_CALIBRATION
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int32_t zephyr_calibration;
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int ret = rtc_get_calibration(rtc_dev, &zephyr_calibration);
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if (ret == -ENOSYS || ret == -ENOTSUP) {
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mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_calibration);
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}
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CHECK_ZEPHYR_RESULT(ret);
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return zephyr_calibration / CALIBRATION_PPM_TO_ZEPHYR;
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#else
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// The Zephyr RTC calibration syscall only exists with
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// CONFIG_RTC_CALIBRATION, which is off unless a driver needs it.
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mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_calibration);
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#endif
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}
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void common_hal_rtc_set_calibration(int calibration) {
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#ifdef CONFIG_RTC_CALIBRATION
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int ret = rtc_set_calibration(rtc_dev, (int32_t)calibration * CALIBRATION_PPM_TO_ZEPHYR);
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if (ret == -ENOSYS || ret == -ENOTSUP) {
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mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_calibration);
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}
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CHECK_ZEPHYR_RESULT(ret);
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#else
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mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_calibration);
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#endif
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}

‎ports/zephyr-cp/common-hal/rtc/RTC.h‎

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// This file is part of the CircuitPython project: https://circuitpython.org
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//
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// SPDX-FileCopyrightText: Copyright (c) 2026 Scott Shawcroft for Adafruit Industries
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//
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// SPDX-License-Identifier: MIT
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#pragma once
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// The RTC device is selected by the devicetree `rtc` alias, following
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// Zephyr's own RTC sample (samples/drivers/rtc). The rtc module is only
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// enabled (CIRCUITPY_RTC=1) when the alias exists and CONFIG_RTC is on, so
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// common-hal/rtc/RTC.c can always DEVICE_DT_GET(DT_ALIAS(rtc)).

‎ports/zephyr-cp/common-hal/rtc/__init__.c‎

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// This file is part of the CircuitPython project: https://circuitpython.org
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//
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// SPDX-FileCopyrightText: Copyright (c) 2026 Scott Shawcroft for Adafruit Industries
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//
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// SPDX-License-Identifier: MIT

‎ports/zephyr-cp/cptools/zephyr2cp.py‎

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@@ -731,6 +731,7 @@ def zephyr_dts_to_cp_board(board_id, portdir, builddir, zephyrbuilddir, mpconfig
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config_bt_found = False
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config_adc_enabled = False
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config_dac_enabled = False
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config_rtc_enabled = False
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config_present = True
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config = zephyrbuilddir / ".config"
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if not config.exists():
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config_adc_enabled = line.strip().endswith("=y")
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elif line.startswith("CONFIG_DAC="):
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config_dac_enabled = line.strip().endswith("=y")
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elif line.startswith("CONFIG_RTC="):
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config_rtc_enabled = line.strip().endswith("=y")
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runners = zephyrbuilddir / "runners.yaml"
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runners = yaml.safe_load(runners.read_text())
@@ -1693,6 +1696,21 @@ def zephyr_dts_to_cp_board(board_id, portdir, builddir, zephyrbuilddir, mpconfig
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board_info["analogio"] = (adc_present and config_adc_enabled) or (
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dac_present and config_dac_enabled
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)
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board_info["rtc"] = False
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# RTC needs both a devicetree `rtc` alias pointing at the RTC device
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# (the same selection Zephyr's own RTC sample uses) and the Zephyr RTC
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# driver layer enabled (CONFIG_RTC).
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rtc_node = device_tree.alias2node.get("rtc")
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if rtc_node is not None:
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rtc_status = rtc_node.props.get("status")
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rtc_present = rtc_status is None or rtc_status.to_string() == "okay"
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if rtc_present and config_rtc_enabled:
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board_info["rtc"] = True
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elif rtc_present:
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logger.warning(
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"Devicetree has a status-okay 'rtc' alias but CONFIG_RTC is "
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"not enabled, so the rtc module is disabled."
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)
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board_info["usb_num_endpoint_pairs"] = usb_num_endpoint_pairs
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# Detect NVM partition size from the device tree.

‎ports/zephyr-cp/prj.conf‎

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CONFIG_EVENTS=y
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# Enable the RTC driver layer so boards with a status-okay `rtc` devicetree
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# alias (e.g. native_sim's rtc-emul, STM32, RP2040, SmartBond) get a working
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# rtc module via common-hal/rtc. Boards without the alias only pay for the
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# tiny RTC core (syscall table + rtc_utils).
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CONFIG_RTC=y
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CONFIG_SERIAL=y
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# Fail quickly on hung I2C devices (probe/scan also uses this timeout)

‎ports/zephyr-cp/supervisor/port.c‎

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#include "common-hal/audiobusio/I2SOut.h"
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#endif
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#if CIRCUITPY_RTC
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#include "shared-bindings/rtc/__init__.h"
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#endif
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#include <stdlib.h>
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#include <zephyr/autoconf.h>
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i2sout_reset();
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#endif
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#if CIRCUITPY_RTC
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rtc_reset();
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#endif
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#if defined(CONFIG_ARCH_POSIX)
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native_sim_reset_port_count++;
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if (native_sim_port_resets != INT32_MAX &&

‎ports/zephyr-cp/tests/test_rtc.py‎

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# SPDX-FileCopyrightText: 2026 Scott Shawcroft for Adafruit Industries
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# SPDX-License-Identifier: MIT
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"""Test the rtc module against native_sim's emulated RTC.
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On a fresh boot the RTC has never been set (the emulated driver has no
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battery backup), so reading it must give the start of the CircuitPython
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epoch, 2000-01-01, rather than an error. Setting the datetime must update
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what time.localtime() reports, and the RTC must advance on its own.
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"""
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import pytest
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RTC_SET_CODE = """\
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import rtc
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import time
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r = rtc.RTC()
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t = time.localtime()
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print("UNSET:", t.tm_year, t.tm_mon, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec)
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r.datetime = time.struct_time((2025, 7, 4, 12, 34, 56, 4, -1, -1))
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t = time.localtime()
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print("SET:", t.tm_year, t.tm_mon, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec)
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time.sleep(2)
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t = time.localtime()
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print("ADVANCED:", t.tm_year, (t.tm_hour, t.tm_min, t.tm_sec) != (12, 34, 56))
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try:
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r.calibration = 1
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except NotImplementedError:
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print("CALIBRATION NOT SUPPORTED")
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"""
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@pytest.mark.circuitpy_drive({"code.py": RTC_SET_CODE})
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@pytest.mark.duration(30)
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def test_rtc_set_and_get(circuitpython):
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"""Setting rtc.RTC().datetime updates time.localtime() and advances."""
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circuitpython.serial.wait_for("UNSET: 2000 1 1", timeout=30)
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circuitpython.serial.wait_for("SET: 2025 7 4 12 34 56", timeout=30)
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circuitpython.serial.wait_for("ADVANCED: 2025 True", timeout=30)
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circuitpython.serial.wait_for("CALIBRATION NOT SUPPORTED", timeout=30)

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