树莓派2 Model B安装Hwclock RTC DS3231模块技术求助

Hey there! Let's walk through your DS3231 RTC setup and fix the key issues in your current process, plus cover the critical steps you might be missing.

First, Correct Your Existing Mistakes #

Looking at your steps, there's one obvious error that'll block your DS3231 from working:

• In step 3, you added dtoverlay=i2c-rtc,ds1307 to /boot/config.txt — but you're using a DS3231 chip! The overlay parameter must match your exact RTC model. Let's fix that first.

Full Step-by-Step Correct Setup #

1. Fix the Device Tree Overlay #

Run this command to edit the config file:

sudo nano /boot/config.txt

Replace the incorrect line with:

dtoverlay=i2c-rtc,ds3231

Save and exit with Ctrl+O, press Enter, then Ctrl+X.

2. Clean Up Module Loading #

Your /etc/modules entry can be adjusted for clarity and correctness. Run:

sudo nano /etc/modules

Add these lines (one per module, instead of combining them):

i2c-bcm2708
i2c-dev

Save and exit.

3. Disable the Fake Hardware Clock (Critical for Wheezy) #

Raspbian Wheezy uses a fake software-based clock by default, which will conflict with your physical DS3231. Let's disable it completely:

# Stop the running service
sudo /etc/init.d/fake-hwclock stop
# Prevent it from starting on boot
sudo update-rc.d fake-hwclock remove
# Optional but recommended: Uninstall the package
sudo apt-get remove fake-hwclock

4. Update the hwclock Configuration #

You already made a backup of /etc/default/hwclock — great move! Now tweak the active config to use your RTC:

sudo nano /etc/default/hwclock

Ensure these lines are set correctly:

HWCLOCKACCESS=yes
HWCLOCKPARS=
SHOWCLOCK=no
HCTOSYS_DEVICE=/dev/rtc0

Save and exit.

5. Reboot and Verify the RTC #

Reboot your Pi to apply all changes:

sudo reboot

After reboot, check if the DS3231 is detected on the I2C bus:

sudo i2cdetect -y 1

You should see 68 in the output — that's the default I2C address of the DS3231.

Next, set your system time and write it to the RTC:

# Replace with your current local time
sudo date -s "2024-05-20 14:30:00"
# Write system time to RTC
sudo hwclock -w

Verify the RTC is reading the correct time:

sudo hwclock -r

This should return the time you just set.

6. Test Persistence (Optional) #

To make sure the RTC keeps time without power:

• Power off your Pi, disconnect it from power for 5-10 minutes
• Power it back on, run sudo hwclock -r — the time should still be accurate.

内容的提问来源于stack exchange，提问作者Rohit