I looked through the datasheet of the DS1307 RTC clock. The datasheet
carefully prevents mentioning the word "I2C" and I dont find any
definitive iniformation whether this "two wore bus" is compatible
with a 3.3V I2C bus as that one on the Beaglebone....
Does anyone out there has successfully used the DS1307 RTC chip
in conjunction with the Beaglbone using its native I2C bus (no bit
banging ) ???
Thank you very much for any information regarding the usage of this
I’ve successfully used the DS1338, which has the same functionality as the DS1307 but operates at 3.3V instead of 5V. I also had to enable the DS1307/DS1338 support in my kernel config, but it seems to be working just fine with the normal Linux “hwclock” commands in Angstrom.
Do you use the bare chip (self soldered) or a breakout board?
Do I have to care of diferent "versions" (like voltage, freqs et
cetera) when using a RTC on the SPI bus instead of one for the I2C?
I've successfully used the DS1338, which has the same functionality
as the DS1307 but operates at 3.3V instead of 5V. I also had to
enable the DS1307/DS1338 support in my kernel config, but it seems to
be working just fine with the normal Linux "hwclock" commands in
As a "me too":
I run the DS1339C-33# (3.3V signaling and power with internal crystal)
on my bone without issue.
. It is attached to SPI instead of I2C. Unfortunatley the
BeagleboneSRM does not tell me that much about SPI.
I think the high precision of this clock and the additional
temperature measuring makes this one also an interesting item.
Will it work on the SPI of the beaglebone or do I need additional
power eating parts.... ???
Well, I can’t really say from experience, but the kernel config looks like it natively supports the DS3234 over SPI if you recompile the kernel with that option configured. I’m not sure what your criteria is for selecting that part over the other, but why not give it a whirl and let us know how it goes?
I wired the DS1339 to I2C2 on the bone, same as the EEPROMs on capes.
The addresses won't conflict. Power came from VDD_3V3EXP. You don't
_need_ pullups on the DS1339 if you have a cape attached, but it's
recommended to use the values from the SRM for I2C devices.
Changes required to support from the kernel include modifying the
board-file to add the DS1339 platform info and then making sure
i2c2_init() gets called. Something like:
Thanks a lot Andrew for you quick reply. I will try this out. Is a
breakout board available for DS1339 ? I checked Adafruit and
Sparkfun, they only have DS3234, DS1307 & DS3231.
Not that I know of. You can buy wide SOIC perf board from Digikey or
similar for about $20 which should work well. The main issue with the
DS1339C version is that a lot of the pins all need to be tied to
ground and doing the pullups, it's easy on the perf board, but a bit
hard without (although it is doable if you're patient).