Topic

rtc

A collection of 10 issues

TCXO RTC Raspberry Pi Hat, part 2

The motivation for this project is NTP servers in datacenters - it can be expensive to get a GPS antenna on top of other people's buildings with a wire running down into your rack. The question is, how do you maximize the accuracy of a stratum 2 NTP

TCXO RTC Raspberry Pi Hat

History I'm bringing my RTC Hats [https://blog.dan.drown.org/tag/stratum2/] back online (source code [https://github.com/ddrown/stm32-input-capture-f031] and hardware design [https://github.com/ddrown/stm32-input-capture-f031/tree/master/hardware] is on github). I originally designed it for frequency synchronization without phase alignment [https://blog.

Drift

One of my goals with the RTC Pi Hats [https://blog.dan.drown.org/tag/stratum2/] was to have a more stable local frequency. This is useful when you can't reach your upstream clock. GPS modules lose signal from time to time, especially when your antenna is less

TCXO aging part 2

The previous data I have on aging [https://blog.dan.drown.org/tcxo-rtc-hats-aging-rtc-frequency/] covered 10 days, and now I want to come back to this now that more time has passed. This data is from the same Pi Hat hardware as that post. The datasheet specification for aging with these

TCXO RTC Hats: aging & RTC frequency

I'm focusing on oscillator aging and RTC frequency in this post. See also: initial data [https://blog.dan.drown.org/tcxo-rtc-hats-initial-data/], picture [https://blog.dan.drown.org/tcxo-rtc-hats/], other stratum 2 posts [https://blog.dan.drown.org/tag/stratum2/] I've been letting these boards run to

TCXO RTC Hats: Initial data

The TCXO RTC hats [https://blog.dan.drown.org/tcxo-rtc-hats/] are collecting data. I'm focusing on the RTC part in this post. See also: other stratum 2 posts [https://blog.dan.drown.org/tag/stratum2/] Required picture This hat is on an Odroid C2. The GPS module on

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.

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