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 NTS part 2 Part 1: Packet format of Network Time Security I wanted to measure the overhead that NTS adds to NTP. To give a rough estimate, I modified the benchmark program included in libaes_siv
ntp NTP security (NTS) I've been hearing about Network Time Security (NTS) being in development for awhile now. With Cloudflare's release of a public NTS service, I wanted to take a closer look at the protocol and
ntp Embedded NTP client/NTP interleaved mode, part 2 Hardware transmit timestamps added to NTP client.
ntp APU2 NTP server I bought an apu2c0. I believe it will make a better NTP server than my other NTP servers.
ntp RK3328 based NTP server I got a ROC-RK3328-CC SBC because it has true gigabit ethernet, emmc, and USB3. These are all better I/O options than the latest Raspberry Pi 3 B+. I put a SATA hard
TL-MR3020 NTP server, part 2 Part 1 was about the hardware, now for the software Step 1: pps-gpio-poll package This architecture doesn't support device tree yet, so it has a special pps driver. The repo for the driver
TL-MR3020 NTP server I have a small travel router that I no longer use, and I wanted to turn it into a NTP server. The hardware is pretty well documented here: https://openwrt.org/toh/tp-link/
SDR Sharp Wireless Weather Station, part 4 part 1, part 2, part 3 Turn the receiver off between messagesTo save power and cpu, I wanted to turn the RTL-SDR off between messages. Because the next message comes at a set
SDR Sharp Wireless Weather Station, part 3 part 1, part 2, part 4 Reverse engineering the CRC In looking at the crc field, I tried a number of different things. rtl_433 crc functions First, I tried the crc7, crc8,
SDR Sharp Wireless Weather Station, part 2 part 1, part 3, part 4 rtl_433 The rtl_433 project has support for decoding a bunch of different weather station devices. Unfortunately, it doesn't support this sharp device. Turning on rtl_
SDR Sharp Wireless Weather Station, part 1 What is the goal? I have a weather station with a wireless temperature/humidity sensor. Instead of looking at the LCD on the wall, I'd like to have that data on my phone.
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 DOCSIS 3.1 and NTP Spectrum upgraded my area to DOCSIS 3.1 to offer 1G/40M service. I believe they have it configured for 1.7Gbit shared downstream (using DOCSIS 3.1) and ~100Mbit shared upstream (sharing
bluetooth BLE: micro:bit UART Experimenting with the micro:bit's Bluetooth UART support. This will explore the lower level guts of how Nordic's Bluetooth Low Energy UARTs work. There are tools to make this easier and less full
stratum2 Drift One of my goals with the RTC Pi Hats 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
TCXO TCXO aging part 2 The previous data I have on aging 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
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
