stm32 Debian for STM32MP1 I bought a STM32MP1 dev board because it has a gigabit NIC with 1588 PTP timestamps as well as hardware timers that can timestamp PPS events without interrupt latency and jitter. I am
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.
gps GPS module measurements, part 2 After the previous tests, I ordered another GPS antenna to improve the signal conditions. They're just the cheap puck style antennas with SMA connectors ($10 on Amazon), and I've put them on my
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. GPIO PPS is
ntp TCXO RTC Hats: aging & RTC frequency I'm focusing on oscillator aging and RTC frequency in this post. See also: initial data, picture, other stratum 2 posts I've been letting these boards run to see what happens. My TCXO's aging
stm32 GNUK: Open Source GPG/SSH hardware key storage I noticed the GNUK project had support for the STM32 Blue Pill. I've been looking for an open source hardware key storage for GPG/SSH keys, so I tried it out. GNUK supports
ntp TCXO RTC Hats: Initial data The TCXO RTC hats are collecting data. I'm focusing on the RTC part in this post. See also: other stratum 2 posts Required picture This hat is on an Odroid C2. The GPS
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, 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
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. The sensors are: one built into the stm32 chip, a TMP36
time Frequency synchronization without phase in NTP I've been working on my high accuracy RTC project. 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
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