Difference between revisions of "Adafruit: RTC DS1307"
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[[File:DS1307 BBB.JPG|300px|Wiring for DS1307 RTC with Beaglebone Black.
== Overview ==
== Overview ==
Revision as of 20:00, 10 December 2013
Inputs and Outputs
The RTC must be powered from the BeagleBone's 5V supply (note it must be powered from the DC adapter, or else I2C bus will hang, as there is not enough current provided by the usb bus to power the RTC). The RTC uses an I2C interface to communicate with the BBB.
On boot BBB is connected power from the DC power adapter, therefore it loads the correct /dev/rtc modules.
P9 pin # (BeagleBone pin) -> Panel pin (wire color)
1 (GND) -> GND
5 (VDD_5V) -> VCC 5 (VDD_5V) -> SQW (through 10k pullup resistor)
19 (I2C2_SCL) -> SCL
20 (I2C2_SCL) -> SDA
#!/bin/bash a=$(date +%Y) if [[ $a < 2013 ]]; then echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device echo "Retrieving time from rtc" hwclock -s -f /dev/rtc1 hwclock -w echo "Date has been read from RTC, and copied to system clock" else # Assumes if date is correct on reboot, that you are connected to network echo "Fetching time from ntp server" $(/usr/bin/ntpdate -b -s u pool.ntp.org) if [ -e /dev/rtc1 ]; then echo "Writing system clock to RTC" hwclock -w -f /dev/rtc1 else echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device echo "Writing system clock to RTC" hwclock -w -f /dev/rtc1 fi fi # Sets time zone to Eastern (GMT -5) $( ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime ) echo "The new date is:" $(date)