TCXO RTC Hats
My new stratum 2 NTP server hats arrived from Macrofab today! I have a few hand
soldering things to do (32khz crystal and headers), and then I can start
calibrating them.
More issues
NIC interrupt coalesce impact on NTP
I noticed that my Odroid C2 system had a much higher round-trip time than I had
expected. It has a gigabit ethernet built into the CPU, so it should be decent.
rtt min/avg/max/mdev = 0.577/0.605/0.627/0.020 ms (10x ICMP pings)
To compare
Temperature compensation, part 2
In the last part [https://blog.dan.drown.org/temperature-compensation/], I measured the TCXO
to fit a frequency vs temperature curve.
Frequency vs Temperature curve
Below are the final curves that I went with for the two systems, and a
comparison of the median frequency at each temperature point. The
Temperature compensation
Temperature effects are usually the largest source of frequency changes in
clocks. So I have three temperature sensors on my test system
[https://blog.dan.drown.org/frequency-synchronization-without-phase-in-ntp/].
The sensors are: one built into the stm32 chip, a TMP36 sensor
[http://www.analog.com/media/en/technical-documentation/data-sheets/TMP35_36_
Frequency synchronization without phase in NTP
I've been working on my high accuracy RTC project
[https://blog.dan.drown.org/stm32f030-devboard-with-tcxo/].
Here's a picture of one of the two systems:
Connections
The TCXO devboard, BME280, and PCF RTC are all on the i2c bus. The TMP36 sensor
is hidden behind a wire
RTC comparison
Real Time Clocks
I bought two high accuracy RTC (real time clock) modules and wanted to compare
them. RTCs are useful for very low power clocks. They can run for years off of a
coin cell battery. Both of these modules are special in they claim higher
accuracy than your
Turris Omnia
My Turris Omnia arrived today!
LED colors based on Network Traffic
Video of it in action: https://youtu.be/bMkGp54xWqQ
Forum post: https://forum.turris.cz/t/led-color-based-on-bandwidth-usage/1262
Blinky Lights
The RGB LEDs can be controlled by sysfs, the "A" and "B" ones are available
stm32f030 devboard with TCXO
I'm interested in making a high accuracy real time clock (RTC). To experiment
with the hardware I need for that, I created a development board based on the
STM32F030F4P6 (which is a 20-TSSOP package) and a TCXO.
I chose that STM32 for two reasons: one, because it'
GPS PPS drift when it has no signal
Question: What happens to a GPS receiver's pulse per second (PPS) when it loses
signal for a long time?
To answer this, I first moved the antenna away from the window and put it in an
anti-static bag.
I did this on the 16th at 01:02 GMT.
Getting Fedora Server running on the Utilite Standard
I installed the Fedora ARM Server image on a Utilite Standard
[http://utilite-computer.com/web/utilite-models] (which is based on a dual-core
Freescale iMX6 1GHz). Not everything is working, but these are my notes.
download the Fedora ARM Server image from https://arm.fedoraproject.org/
There are installation instructions at