Dan's notes (Page 7)

More issues

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. A graph of historical data would be nice as well. What am I starting with?

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), and I've put them on my windowsill. There's something wrong with

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 have on hand is a 72MHz STM32 devboard. I used the input capture hardware on

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 the legacy DOCSIS 3.0 upstream channels). This is unverified because the modem (a Technicolor TC4400-AM) has

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 of guts, but they hide the details. Device one: micro:bit, code: https:

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

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.drown.org/gps-module-measurements-part-3/]. GPIO PPS is one of the best ways to get that timing

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

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 the OpenPGP smartcard protocol, and has space for 3 keys. The keys are named: "