If the returned date and time is not correct, or “hwclock” returns an error, use the “-w”
option to set the hardware clock to the current time:
$
sudo hwclock -w
Then recheck the time stored in the hardware clock to ensure it matches. Linux may have
failed to automatically update the hardware clock after the last reboot if its internal
registers contained invalid values.
If the RTC still doesn’t work, you should check if the Pi sees the RTC chip on the I
2
C bus.
Run these two commands:
$
sudo modprobe -r rtc_ds1307
$
sudo i2cdetect 1
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-1.
I will probe address range 0x03-0x77.
Continue? [Y/n]
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- --
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6f
70: -- -- -- -- -- -- -- —
You should see “6f” in the address list. This is the address of the RTC.
If the RTC address is detected, double check your software installation for issues at the
Linux modules level.
Run the “lsmod” command to list the loaded modules and check that “i2c_dev” and
“i2c_bcm2708” are both listed.
If the RTC address is not detected, the cause could be a hardware problem, on the Strato
board or the Raspberry Pi. If you have another Pi or Strato board, try swapping them to
isolate the faulty board.
Configuring the serial port
On Raspberry Pi 3 and 4, the main UART (ttyAMA0) is used by default for Bluetooth, and
the TX/RX pins on the GPIO connector are controlled by a limited function Mini UART
(ttyS0).
To route the main UART to the RX/TX pins that are connected to the Strato Pi serial ports
you could disable Bluetooth. Edit /boot/config.txt and add these lines at the end of the file:
# Disable Bluetooth
dtoverlay=pi3-disable-bt
You may also run the following command to disable the Bluetooth HCI UART driver:
sudo systemctl disable hciuart
Alternatively, you may use the pi3-miniuart-bt overlay to switch Bluetooth to use the mini
UART (ttyS0), and restore ttyAMA0 to GPIOs 14 and 15. Refer to the Raspberry Pi UARTs
documentation page for additional information.
https://www.raspberrypi.org/documentation/configuration/uart.md
18
Strato Pi UPS User Guide
