> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man4/ds1307.4.md).

# ds1307.4

`ds1307` — 64 x 8 串行 I2C 实时时钟（RTC）

## 名称

`ds1307`

## 概要

`device iic device iicbus device ds1307`

## 描述

`ds1307` 串行实时时钟（RTC）是一种低功耗、全二进制编码十进制（BCD）时钟/日历，外加 56 字节的 NV SRAM。

`ds1307` 具有内置电源检测电路，可检测电源故障并自动切换到备用电源。当器件由备用电源供电时，计时操作继续进行。

通过 [sysctl(8)](/man/man8/sysctl.8.md) 接口访问 `ds1307` 设置：

```sh
dev.ds1307.0.%desc: Maxim DS1307 RTC
dev.ds1307.0.%driver: ds1307
dev.ds1307.0.%location: addr=0xd0
dev.ds1307.0.%pnpinfo: name=rtc compat=maxim,ds1307
dev.ds1307.0.%parent: iicbus1
dev.ds1307.0.sqwe: 1
dev.ds1307.0.sqw_freq: 32768
dev.ds1307.0.sqw_out: 0
```

**`dev.ds1307.%d.sqwe`** 若设为 1，SQW 引脚输出频率为 `dev.ds1307.%d.sqw_freq` 的方波。若设为 0，SQW 引脚的输出电平由 `dev.ds1307.%d.sqw_out` 控制。

**`dev.ds1307.%d.sqw_freq`** 在 `dev.ds1307.%d.sqwe` 上启用方波输出时选择 SQW 引脚的频率。可设为 1、4096、8192 和 32768。

**`dev.ds1307.%d.sqw_out`** 当 `dev.ds1307.%d.sqwe` 设为 0 时设置 SQW 引脚的输出电平。

更多详情请查阅 `ds1307` 数据手册。

在基于 [device.hints(5)](/man/man5/device.hints.5.md) 的系统（如 `MIPS`）上，这些值可为 `ds1307` 配置：

**`hint.ds1307.%d.at`** `ds1307` 所连接的 [iicbus(4)](/man/man4/iicbus.4.md)。

**`hint.ds1307.%d.addr`** `ds1307` 的 i2c 地址。

在基于 FDT(4) 的系统上，必须设置以下属性：

**`compatible`** 必须始终设为"dallas,ds1307"或"maxim,ds1307"。

**`reg`** `ds1307` 的 i2c 地址。`ds1307` 的默认地址为 0xd0。

## 参见

[fdt(4)](/man/man4/fdt.4.md), [iic(4)](/man/man4/iic.4.md), [iicbus(4)](/man/man4/iicbus.4.md), [sysctl(8)](/man/man8/sysctl.8.md)

## 历史

`ds1307` 驱动首次出现于 FreeBSD 11.0。

## 作者

`ds1307` 驱动及本手册页由 Luiz Otavio O Souza <loos@FreeBSD.org> 编写。


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