PrincessPi/Precision-Timekeeping-Fuckery
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clean up clean up everybody everywhere clean up clean up come on everybody do your share

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Princess Pi
2026-03-28 06:11:46 -06:00
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Grandfatherclock.md
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# Version 3:
# Version 3
## To Figure Out
@@ -11,17 +11,18 @@
6. Best GPS Antenna+Cable for it
7. PPS Settings
8. UART Speed settings
9. Any pulse out (32kHz maybe?)
9. Any pulse out (32kHz/ maybe?)
2. [Pulsar Clock](Pulsar-Clock.md)
1. all daaat shit lmao
## Hardware
1. Raspberry Pi 5 16GB
1. Raspberry OS Lite
2. Will need to carefully use real time priority, maybe even pinned to a core?
3. gpsd, etc?
4. reading pulses/etc
5. uart?
```bash
sudo taskset -cp 2 1234 # set task pid 1234 pin to core 2
@@ -30,44 +31,82 @@ sudo taskset -cp 2 1234 # set task pid 1234 pin to core 2
```bash
sudo chrt -f -p 90 1234 # set pid 1234 to priority 90 (1-99  highest)
```
1. RTC 32khz pulses
1. RTC 32khz pulses (31.25us period)
2. pulsar readings
3. RTC set/read
3. RTC set/read over i2c
4. GPS Module PPS
1. gpsd, etc?
5. NVME hat for NVME boot (? IF NOT INTERFERE WITH GPIO SHIT)
1. NVME SSD (? IF NOT INTERFERE WITH GPIO SHIT)
6. **Custom Hat**
1. 1. [RTC](https://www.adafruit.com/product/3013#tutorials) x2
1. [Adafruit DS3231 RTC Precision I2C Breakout Module](https://www.adafruit.com/product/3013#tutorials) x1
[CR1220](https://www.adafruit.com/products/380) x1 (Battery)
7. [Gen 10 Timekeeping Specific GPS Module - NEO-F10T](https://gnss.store/collections/neo-f10t-timing-gnss-modules)
1. [CR1220](https://www.adafruit.com/products/380) x2 (Battery)
1. Gen 10 Timekeeping Specific GPS Module - NEO-F10T
1.  [Buy Varieties (Europe)](https://gnss.store/collections/neo-f10t-timing-gnss-modules)
1.  [Buy Varieties (Europe)](https://gnss.store/collections/neo-f10t-timing-gnss-modules)
1. Make sure battery TYPE and APPLICATION is figured out
1. Make sure battery TYPE and APPLICATION is figured out
1. May have to solder in holder or something
2. Make sure GPIO pins are FUCKING 2.54mm AND 3.3v OR 5v
1. use goldddd ones~
3. Make sure antenna connector is gonna work
1. GPS cable
2. GPS antenna
2. [Product Summary](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_ProductSummary_UBX-22025534.pdf)
2. May have to solder in holder or something
8. GPS Module
1\. [Gen 10 Timekeeping Specific GPS Module - NEO-F10T](https://gnss.store/collections/neo-f10t-timing-gnss-modules)
3. [Data Sheet](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_DataSheet_UBX-22022576.pdf)
1. [Product Summary](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_ProductSummary_UBX-22025534.pdf)
2. [Data Sheet](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_DataSheet_UBX-22022576.pdf)
3. [Hardware Integration Guide](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_IntegrationManual_UBX-22018271.pdf)
4. [Chip Product Page](https://www.u-blox.com/en/product/neo-f10t-module)
4. [Hardware Integration Guide](https://content.u-blox.com/sites/default/files/documents/NEO-F10T_IntegrationManual_UBX-22018271.pdf)
```
2. Make sure GPIO pins are FUCKING 2.54mm AND 3.3v OR 5v
1. use goldddd pinssss~
3. GPS cable
1. check connectors
2. check adaptors
3. check variety
1. speed/length
2. check length
4. GPS antenna
1. check protos
2. check bands
3. check features
4. check connectors
```
5. [Chip Product Page](https://www.u-blox.com/en/product/neo-f10t-module)
## RPI5 Wiring
- [GPIO Simple Pinout](https://vilros.com/pages/raspberry-pi-5-pinout)
- [GPIO Detailed Pinout](https://pinout.xyz/pinout/3v3_power)
### Wiring of Note
- CLK/PCM/GPIO18/PIN12:
- CLK in/out up to 10mHz (1ns period)
- ![9824306b308e6d2d21274a5bfe933c6b.png](../../_resources/9824306b308e6d2d21274a5bfe933c6b.png)
- only one i2c port?
- mostly all 3v3?
- PCM is kinda like DAC?
- GPIO Read?
- PWM?
- find sum DAC/ADC? sumtin?
- **May have to nix double RTC Module**
### Wiring
- UART (GPS Module, tinker with speed)
- I2C (RTC)
- CLK/PCM/GPIO READ? (RTC 32khz pulse - 31.25us period)
## Operation Flow
Both RTCs loaded time over I2C, both inputting 32kHz signal via GPIO
Both RTCs loaded time over I2C, both inputting 32kHz (31.25us period) signal via GPIO
Dual RTC time, GPS time, system time, GPS PPS, dual 32kHz signals, pulsar readings:
RTC time, GPS time, system time, GPS PPS, 32kHz (31.25us period) signal, pulsar readings:
- tested off each other
- deltas per pulse (errors) (add to Grafana)
@@ -75,18 +114,14 @@ Dual RTC time, GPS time, system time, GPS PPS, dual 32kHz signals, pulsar readin
- stored in histograms, constantly updating (add to Grafana)
- dial in desired confidence interval over time (add to Grafana)
- divisor/multiplier for 32kHz pulses to make them ONE BEAT constantly updated (displayed in Grafana)
- one 32kHz oscillator (the most reliable) will be dubbed the "master universal beat pulse", made into pulse by divisor/multiplier based on previous calculations
- 32kHz oscillator (31.25us period) (or most reliable) will be dubbed the "master universal beat pulse", made into pulse by divisor/multiplier based on previous calculations
- and will serve as source of truth for UBT web display
- sanity tested against network sources
1. Test both RTC times against GPS time
2. Test system time against GPS time
3. Test system time against network time
4. Sanity Checks
1. Time reported vs time actual (net)
2. Cable/system delay calculated vs delay measured
3. Readability check
@@ -97,8 +132,4 @@ Dual RTC time, GPS time, system time, GPS PPS, dual 32kHz signals, pulsar readin
## Maybe
1. Play with PPS (dial faster?)
2. Play with UART speed (dial faster?)