58 lines
2.1 KiB
Markdown
58 lines
2.1 KiB
Markdown
|
# Real Time Clock
|
||
|
|
It is practical to have a real time clock (RTC) built into your system. With this you are more flexible and have less problems with connections and scanning of devices.
|
||
|
|
|
||
|
|
# automatic sync ntp
|
||
|
|
To automatic sync with an ntp server use
|
||
|
|
```bash
|
||
|
|
sudo timedatectl set-time "2020-04-23 8:38"
|
||
|
|
# or
|
||
|
|
timedatectl set-ntp True
|
||
|
|
```
|
||
|
|
|
||
|
|
# DS1307 RTC
|
||
|
|
- 5V DC supply
|
||
|
|
- Automatic Power-Fail detect and switch circuitry
|
||
|
|
- Consumes less than 500nA in Battery-Backup Mode with Oscillator Running
|
||
|
|
- 56-Byte, Battery-Backed, Nonvolatile (NV)RAM for data storage
|
||
|
|
- I2C ADDRESS 0x68
|
||
|
|
|
||
|
|
Pinout
|
||
|
|
| PIN | Description | Comment |
|
||
|
|
| --- | ------------------- | ------------------------------------------------ |
|
||
|
|
| BAT | Battery voltage | To monitor the battery voltage, or not connected |
|
||
|
|
| GND | Ground | Ground |
|
||
|
|
| VCC | 5V supply | Power the module and charge the battery |
|
||
|
|
| SDA | I2C data | I2C data for the RTC |
|
||
|
|
| SCL | I2C clock | I2C clock for the RTC |
|
||
|
|
| DS | Temp. Sensor output | One wire inteface |
|
||
|
|
| SQ | Square wave output | Normally not used |
|
||
|
|
|
||
|
|
## Setting up
|
||
|
|
```bash
|
||
|
|
nano /boot/config.txt
|
||
|
|
# add: dtoverlay=i2c-rtc,ds1307
|
||
|
|
reboot
|
||
|
|
i2cdetect -y 1
|
||
|
|
# You should see a wall of text appear, if UU appears instead of 68 then we have successfully loaded i2c in the Kernel driver
|
||
|
|
|
||
|
|
# Remove fake system clock
|
||
|
|
sudo apt -y remove fake-hwclock
|
||
|
|
sudo update-rc.d -f fake-hwclock remove
|
||
|
|
sudo nano /lib/udev/hwclock-set
|
||
|
|
# Find and Comment out
|
||
|
|
> if [ -e /run/systemd/system ] ; then
|
||
|
|
> exit 0
|
||
|
|
> fi
|
||
|
|
# read the time directly
|
||
|
|
sudo hwclock -D -r
|
||
|
|
# read the system time
|
||
|
|
date
|
||
|
|
```
|
||
|
|
|
||
|
|
If the time displayed by the date command is correct, you can go ahead and run the following command on your RPi. This command will write the time from the RPi to the RTC Module.
|
||
|
|
```bash
|
||
|
|
sudo hwclock -w
|
||
|
|
# and verify
|
||
|
|
sudo hwclock -r
|
||
|
|
```
|