Jetson/RTC
Contents
Basic strategy
Simply follow Santyago's great How-To posted on the forum.
https://devtalk.nvidia.com/default/topic/769727/embedded-systems/-howto-battery-backup-rtc/
- Use Santyago's Grinch Custom Kernel 19.3.4 or above
- Use an RTC module (Dallas DS3231)
- Connect the RTC module on Jetson TK1's I2C bus
Detail
Custom Kernel
Install Santyago's Grinch Custom Kernel.
RTC Module
In the How-To, Santyago shows how to wire Maxim's DS3231, a high precision I²C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. While it is possible to get the chip and wire everything by yourself, it is easier to just get a module that has the same chip.
Adafruit | DealExtreme | Victory7 |
---|---|---|
Product page | Product page | Product page |
There seems to be couple of options. You can get an RTC module with DS3231 from Adafruit, DealExtreme and some other. DS1307 based RTC module might work, but have not tried.
I used a module from a shop in Japan, this one seems to be originally made for Raspberry Pi. The interface is simple. It's just I2C, so all you need to care is VCC, GND and pins for I2C (SCL and SDA).
Connection and Securing the module on the board
I made wiring from the RTC module to back of the J3A1 headers, so that you can still insert some other things for expansion. There are GND, VCC, SCL and SDA pins from Pin #14 to #20 of J3A1 header in one row.
Pin# on J3A1 | RTC Module | |
---|---|---|
GND | 14 | GND(1) |
VCC | 16 | VCC(4) |
SCL | 18 | SCL(3) |
SDA | 20 | SDA(2) |
The RTC module from Victory7 had a 2.54mm-pitch 4-pin header to go into a breadboard. I took them out for easy mounting. (Wish this in 2mm-pitch and in the same order as pins on the J3A1 header)