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IDProjectCategoryView StatusDate SubmittedLast Update
0000108Bananian Linux[All Projects] Kernelpublic2015-02-24 18:512015-12-25 14:43
Reporterbrandonburg 
Assigned ToNico 
PrioritynormalSeverityfeatureReproducibilityalways
StatusresolvedResolutionfixed 
Product Version15.01 
Target VersionFixed in Version 
Summary0000108: Kernel module rtc-ds1307 for the extremely accurate DS3231 RTC chip is missing
DescriptionThe kernel module "rtc-ds1307" is missing.

This driver is necessary for the extremely accurate I2C-integrated
DS3231 RTC chip. This chip provides an accurate time source for systems that are not connected to the internet. Most RTC chips are not that accurate and provide no reliable time source.

It should also be mentioned that NTP is no longer secure and its usage implies security issues (see http://www.golem.de/news/openbsd-sichere-uhrzeit-mit-ntp-und-https-1502-112370.html [^] [German language]). The DS3231 can be used as an alternative solution.

Another good reason for the "rtc-ds1307" kernel module:
The support of RTC modules helps to preserve the Banana Pi product warranty. It is not neccesary to solder a battery on the PCB. Some users have no soldering equipment.

DS3231
Accuracy ±2ppm from 0°C to +40°C
Accuracy ±3.5ppm from -40°C to +85°C
[ppm - parts per million]

Very tiny plug-in modules are already available for the Raspberry Pi. These modules can also be used on the Banana Pi on CON3 header (pins 1, 3, 5, 7):
http://forum.lemaker.org/thread-4276-1-1-my_humble_experience_with_rtc_and_bananapi.html [^]
Steps To Reproduce/sbin/modprobe rtc-ds1307
Additional InformationHint: It is possible to bend up the supercapacitor/battery on most DS3231 RTC modules, so that the supercapacitor/battery does not collide with pins on J12 header on the Banana Pi. Alternatively, insulating tape may also help to keep the supercapacitor/battery on the module away from the J12 pin header.

Functional check of DS3231 RTC module after module insertion without kernel driver:
/usr/bin/watch -n 0,4 "i2cget -y 2 0x68 0; i2cget -y 2 0x68 1; i2cget -y 2 0x68 2"
(requires: apt-get install i2c-tools )

DS3231 data sheet: http://datasheets.maxim-ic.com/en/ds/DS3231.pdf [^]
TagsDS1307, DS3231, kernel, NTP, RTC
Attached Files

- Relationships
has duplicate 0000139resolvedNico Add rtc modules 

-  Notes
(0000288)
sinuswave (reporter)
2015-10-05 19:57

 The upstream kernel package 4,2 has ds1307 module supprt.
(0000318)
Nico (manager)
2015-12-25 14:43

 Please use our mainline 4.x kernel packages.

- Issue History
Date Modified Username Field Change
2015-02-24 18:51 brandonburg New Issue
2015-02-24 18:58 brandonburg Tag Attached: DS1307
2015-02-24 18:58 brandonburg Tag Attached: DS3231
2015-02-24 18:58 brandonburg Tag Attached: kernel
2015-02-24 18:58 brandonburg Tag Attached: NTP
2015-02-24 18:58 brandonburg Tag Attached: RTC
2015-10-05 19:57 sinuswave Note Added: 0000288
2015-12-25 14:43 Nico Note Added: 0000318
2015-12-25 14:43 Nico Status new => resolved
2015-12-25 14:43 Nico Resolution open => fixed
2015-12-25 14:43 Nico Assigned To => Nico
2015-12-25 14:44 Nico Relationship added has duplicate 0000139

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