ds1307
—
64 x 8, serial, i2c real-time clock
device iic
device iicbus
device ds1307
The ds1307
serial real-time clock (RTC) is a low-power,
full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM.
The ds1307
has a built-in power-sense
circuit that detects power failures and automatically switches to the backup
supply. Timekeeping operation continues while the part operates from the
backup supply.
Access to ds1307
settings is made with the
sysctl(8)
interface:
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
- If set to 1, the SQW pin drives a square-wave of
dev.ds1307.%d.sqw_freq frequency. If set to 0, the
output level of SQW pin is controlled by
dev.ds1307.%d.sqw_out.
- dev.ds1307.%d.sqw_freq
- Select the frequency of the SQW pin when the square-wave output is enabled
on dev.ds1307.%d.sqwe. It can be set to 1, 4096,
8192 and 32768.
- dev.ds1307.%d.sqw_out
- Set the output level of the SQW pin when
dev.ds1307.%d.sqwe is set to 0.
Please check the ds1307
datasheet for more
details.
On a
device.hints(5)
based system, such as MIPS
, these values are
configurable for ds1307
:
- hint.ds1307.%d.at
- The
iicbus(4)
that the
ds1307
is connected to.
- hint.ds1307.%d.addr
- The i2c address of
ds1307
.
On a
FDT(4)
based system the following properties must be set:
- compatible
- Must always be set to "dallas,ds1307" or
"maxim,ds1307".
- reg
- The i2c address of
ds1307
. The default address for
ds1307
is 0xd0.
The ds1307
driver first appeared in
FreeBSD 11.0.
The ds1307
driver and this manual page were written by
Luiz Otavio O Souza
<loos@FreeBSD.org>.