Instructions to Configure DS1307 or DS1338 RTC

[arm2]

To enable support for the RTC in Raspbian Wheezy' (2012-10-28 or later),
the following lines need to be added to /etc/rc.local above the exit0 line:

modprobe i2c-bcm2708
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
modprobe rtc-ds1307
hwclock -s

These instructions should work with any DS1307 or DS1338 Real Time Clocks, it has been tested with CJE Micro's/4D RTC http://www.cjemicros.co.uk/micros/indiv ... eClock-RTC

If anyone has any problems or suggestions re this please post here.

Chris Evans (CJE Micros's & 4D)

[repton]

To enable support for the RTC in Raspbian Wheezy' (2012-10-28 or later),
the following lines need to be added to /etc/rc.local above the exit0 line:

modprobe i2c-bcm2708
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
modprobe rtc-ds1307
hwclock -s

It's important to note that if you are using a Rev2 RasPi then you need to replace i2c-0 with i2c-1.

Paul

[arm2]

Thanks for that info:

Not elegant but would

modprobe i2c-bcm2708
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
modprobe rtc-ds1307
hwclock -s

work?

I'm used to RISC OS where you could have a utility that sets a system variable and then you can have conditional execution in the boot script like:
modprobe i2c-bcm2708
IF Rev$Pi=0 THEN echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
IF Rev$Pi>0 THEN echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
modprobe rtc-ds1307
hwclock -s

[Schorschi]

On Fedora ARM on Pi...

# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
-bash: echo: write error: Invalid argument

Does not seem to work on my Model 2. However, I am still able to set and query the RTC clock. So new_device is set somehow.

[Schorschi]

Thinking more about this... I pulled my older Model 2 with only 256 MB out of obsolete drawer... and tried the same steps, making sure the Fedora ARM image was pristine... since my work bench Model 2 Fedora image has I2C, SPI, and more goodies support already loaded. Long story short the steps as document work, I don't get the invalid write error.

# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
# echo $?
0

[Schorschi]

Just an update... Fedora 18 ARM... support ds1307 has been dropped. This is a real disappointment, because I have i2c ds1307 add-on boards for a few of my Pi devices, and now it appears I have to remain on Fedora 17, or change distributions. Best I can determine, Fedora ARM team decided that since ds1307 based RTCs are not a consistent feature of ARM devices, there was no need to continue support because it establishes what they called an inconsistent platform? Whatever that means.

Reference...
https://lists.fedoraproject.org/pipermail/arm/2013-January/005066.html

[jwasch]

Is anyone aware of any updates to this issue relating to DS1307 support in Fedora 18 (Pidora)?

It appears only the command:

echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_devices

is failing, but that other commands are working okay, such as:

hwclock -r ... to "read" contents of RTC
hwclock -s ... to "set" time/date from contents of RTC
hwclock -w ... to "write" current date into RTC

This presumes performing a "modprobe rtc-ds1307".

Is the "echo ds1307 0x68" command needed for anything?

[MarkoSiroki]

I cannot run

Code: Select all

echo "ds1307 0x68" > /sys/class/i2c-adapter/i2c-1/new_device

inside bash script because it gives me error:

line 3: echo: write error: Invalid argument

. Why?!

[DirkS]

I cannot run

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echo "ds1307 0x68" > /sys/class/i2c-adapter/i2c-1/new_device

inside bash script because it gives me error:

line 3: echo: write error: Invalid argument

. Why?!

What model pi do you have?
Which OS and OS version?
Which kernel version?

[JamesT42]

Try

Code: Select all

echo "ds1307 0x68" | sudo tee /sys/class/i2c-adapter/i2c-1/new_device

[jchernus]

I'm having the same problem.

Details:

Raspberry Pi Model B
Linux raspberrypi 3.18.7+ #755 PREEMPT Thu Feb 12 17:14:31 GMT 2015 armv6l GNU/Linux

Thank in advance!

Julia

[DougieLawson]

Take a look at /boot/overlays/README if dtoverlay=i2c-rtc is documented in there then you've got kernel support.

If it's not there run sudo rpi-update (to get to 3.18.12).

Add

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dtoverlay=i2c-rtc,ds1307

to /boot/config.txt then reboot and your RTC will be running with nothing needed. No strange echo commands are needed.

[jchernus]

Thank you,

I do indeed have the following in the /boot/overlays/README

File: ds1307-rtc-overlay.dtb
Info: Configures the DS1307 Real Time Clock
Load: dtoverlay=ds1307-rtc
Params: <none>

I am able to query and set the hwclock. However, for some reason the hwclock is being set by the system clock on bootup (instead of the other way around).

It's behaviour is the following:

I set the system time to ‘Fri May 1 2015, 7:10AM’.
I set the hwclock time to ‘Fri May 1 2015, 7:10AM’.

I wait five minutes.

Times have moved forward 5 minutes appropriately (‘Fri May 1 2015, 7:15AM’).

I shut the RPi down, wait 5 minutes.

Boot up, and both are set to ‘Fri May 1 2015, 7:15AM’.
Ideally, both would show ‘Fri May 1 2015, 7:20AM’.


Do you have any idea what startup script could be causing this?

Thank you,

Julia

[DougieLawson]

You need to get rid of fake-hwclock and ensure that hwclock gets run at shutdown and again at restart.

[retknow]

I am having the same problem.
When I do

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sudo i2cdetect -y 1

it shows my DS3231 as 68

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pi@raspberrypi ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --                         

. But when I do the

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oech ds1307 0x68 >>  /sys/class/i2c-adapter/i2c-1/new_device

command I get the "permission denied" message.

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echo ds3231 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
bash: /sys/class/i2c-adapter/i2c-1/new_device: Permission denied

I have a model B+
I am quite new here, so please answer in laymen terms

[haccks]

Take a look at /boot/overlays/README if dtoverlay=i2c-rtc is documented in there then you've got kernel support.

If it's not there run sudo rpi-update (to get to 3.18.12).

Add

Code: Select all

dtoverlay=i2c-rtc,ds1307

to /boot/config.txt then reboot and your RTC will be running with nothing needed. No strange echo commands are needed.

Thanks for this. I added

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dtoverlay=i2c-rtc,ds1307

to /boot/config.txt and after reboot I checked hardware clock with

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sudo hwclock -r

. It's showing correct time but the system clock is not set with hardware clock time. What to do now?