Hi, I would like to know if it is possible to connect a Real-time clock (RTC) to the DragonBoard 410c. We’re interested in using the DragonBoard 410c for embedded applications where the power is disconnected frequently and there is no internet connection available. If so, can anyone recommend a specific RTC module and/or installation instructions?
Thanks and regards,
Seeed Studios has a real-time clock module based on the Dallas Semi-conductor DS1307. This module can be easily connected (through a level shifter) to the I2C0 bus on the low-speed expansion connector. I checked in the menuconfig system under real-time-clocks and there is support for the DS1307 in the kernel. you will need to modify the device tree and recompile the kernel with support turned in. At this point you will have a real-time clock that you can read.
Unfortunately I don’t have one of these modules yet so I can’t test it for you. I do not know if the system will probe and read the DS1307 to set the real-time. All I do know is it sure looks like there is support for it.
Full disclosure: I am an employee of Qualcomm Canada. Any opinions I have expressed in this or any other post may not reflect the opinions of my employer.
I managed to get a chance to test a ds1307 today. Once you connect it and make the kernel and device tree changes it works perfectly.
Connect the hardware. You need to connect 5V power and ground. The I2C signals SCL and SDA need to go through a level shifter.
Modify the device tree. in the file arch/arm64/boot/dts/qcom/msm8916.dtsi add the following under blsp_i2c0
compatible = "maxim,ds1307";
reg = <0x68>;
status = "okay";
Once you do all of this the kernel will read the time from the clock at power-up time. If you are connected to the network, the kernel will write the current time into the DS1307.
One more little thing. You need to set the real-time clock, remove the default system clock and install the real time clock.
sudo hwclk –w # write the time.
sudo update-rc.d -f fake-hwclock remove
sudo update-rc.d hwclock.sh enable
i want to ask that for RTC it this python code usefull actually i am unable to figure out.
please find the link below: