BlackMark
cdca5219d0
Same driver surface as the yazoalfa version — clock and alarm get/set, alarm interrupts, flag check/clear — plus oscillator-stop detection and die temperature. One source for tiny85 (software I2C) and mega328P (TWI), built against libavr in both generated and reflect mode, byte-identical .text across modes. Errors surface as std::expected instead of being dropped; weekday-rate alarms now really set the DY bit (legacy cleared it); multi-register access is one coherent bus transaction. Legacy stays on master. Co-Authored-By: Claude <noreply@anthropic.com>
30 lines
1.1 KiB
Markdown
30 lines
1.1 KiB
Markdown
# ds3231
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Maxim DS3231 RTC driver on [libavr](https://git.blackmark.me/avr/libavr):
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clock and alarm read/write, alarm interrupts, oscillator-stop detection,
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die temperature. One source runs on every libavr chip — TWI hardware on
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the mega328P, open-drain software I2C on the tinies. All bus errors
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surface as `std::expected`.
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```cpp
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using bus = dev::i2c<{.frequency = 100_kHz}>;
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using rtc = ds3231::device<bus>;
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auto now = rtc::read_clock(); // result<date_time>
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(void)rtc::set_alarm1({}, ds3231::alarm1_rate::once_per_second);
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```
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`example/main.cpp` is the full tour. Build with a libavr checkout:
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```sh
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LIBAVR_ROOT=/path/to/libavr cmake --preset attiny85-generated
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cmake --build --preset attiny85-generated
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```
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Presets cover attiny85/atmega328p in both libavr modes (generated and
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reflect). The legacy yazoalfa-based driver lives on the `master` branch.
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Differences from legacy: weekday-rate alarms now actually set the DY bit
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(the old `setAlarmHelper` always cleared it), reads/writes are single
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coherent bus transactions, and errors are reported instead of ignored.
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