stm32 - Dan's notes

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

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]

ntp

Embedded NTP client/NTP interleaved mode, part 5

I'll test what happens when I plug my embedded NTP client directly into my NTP servers, bypassing the Ethernet switch. This ends my long running embedded NTP client series. The systems involved Embedded

stm32

Embedded NTP client/NTP interleaved mode, part 4

Part 3 [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-3/] ended with an unexplained 3us offset, this post will reduce that. Verifying PTP clock sync I wanted to measure the NTP client's PTP clock sync

ntp

Embedded NTP client/NTP interleaved mode, part 3

Previous posts: part 1 [https://blog.dan.drown.org/archmax-ntp-client/], part 2 [https://blog.dan.drown.org/embedded-ntp-client-ntp-interleaved-mode-part-2/] In this post, I wrap up my embedded NTP client and use it to measure

stm32mp1

STM32MP1 NTP server, part 2

Previous post: https://blog.dan.drown.org/stm32mp1-ntp-server/ [https://blog.dan.drown.org/stm32mp1-ntp-server/] I figured out my offset problem, which was not a PLL problem like I thought. Connman has a NTP

ntp

STM32MP1 NTP server

Previous post: Debian for STM32MP1 [https://blog.dan.drown.org/debian-for-stm32mp1/] NIC Hardware Timestamps First step: enable hardware timestamps in chrony.conf: chrony configuration for hardware timestampsNext, enable chrony's measurements log, and verify

stm32

Debian for STM32MP1

I bought a STM32MP1 dev board [https://www.st.com/en/evaluation-tools/stm32mp157a-dk1.html] because it has a gigabit NIC with 1588 PTP timestamps as well as hardware timers that can timestamp PPS

arduino

2 button keyboard

I wanted a simple keyboard with play and pause media keys to make it convenient to control my music. To handle the USB, I used a STM32F103 based "blue pill" board because they're

ntp

Embedded NTP client/NTP interleaved mode, part 2

Hardware transmit timestamps added to NTP client.

ntp

Embedded NTP client/NTP interleaved mode

NTP client with hardware timestamps

gps

GPS module measurements, part 2

After the previous tests [https://blog.dan.drown.org/gps-module-measurements/], I ordered another GPS antenna to improve the signal conditions. They're just the cheap puck style antennas with SMA connectors ($10 on Amazon)

gps

GPS module measurements

Starting point I got a u-blox NEO-6M and I wanted to compare it to my NS-T. Since I don't have a frequency counter, I decided to try creating one myself. The hardware I

ntp

PPS over USB

Goal For keeping your system clock on time, you can't beat the Pulse Per Second (PPS) signals available from $10 GPS modules. They typically have better than 100 nanosecond accuracy [https://blog.dan.

ntp

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:

stm32

GNUK: Open Source GPG/SSH hardware key storage

I noticed the GNUK [https://www.fsij.org/category/gnuk.html] project had support for the STM32 Blue Pill [http://wiki.stm32duino.com/index.php?title=Blue_Pill]. I've been looking for an

ntp

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/

ntp

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.

time

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

time

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

time

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

rtc

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

stm32

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