Implement 500ms snapshot telemetry logging and split fault events.

Switch USB backup output from per-signal files to a single wide telemetry_snapshot.csv, add fault edge writes to a dedicated Influx measurement, and migrate format assets to the sc-data-format submodule for consistent updates.

Author: sunpi

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "sc-data-format"]
+	path = sc-data-format
+	url = git@github.com:badgerloop-software/sc-data-format.git

README.md

@@ -4,7 +4,7 @@ A lightweight C daemon for Raspberry Pi that reads raw CAN frames from a SocketC
 
 | Sink | What it does |
 |------|-------------|
-| **CSV logger** | Appends every decoded sample to a per-signal `.csv` file on a USB drive |
+| **CSV logger** | Writes one unified wide snapshot CSV (`telemetry_snapshot.csv`) every 500ms |
 | **InfluxDB** | Batches samples and uploads to InfluxDB Cloud on a configurable interval |
 | **Serial radio** | Periodically serializes the latest value of every active signal and writes it to a UART radio (e.g. RFD900A) for wireless ground-station reception |
 
@@ -134,7 +134,7 @@ cp can_telem.conf.example can_telem.conf
 ```ini
 # ── Core ────────────────────────────────────────────────────────────
 can_interface          = can0
-format_file            = /home/sunpi/can-telem-cloud/format.json
+format_file            = /home/sunpi/can-telem-cloud/sc-data-format/format.json
 output_dir             = /mnt/usb
 
 # ── InfluxDB Cloud (optional) ───────────────────────────────────────
@@ -176,7 +176,7 @@ CLI flags override values in the config file.
 
 ## CSV output
 
-One file per signal at `<output_dir>/<signal_name>.csv`:
+One unified snapshot file at `<output_dir>/telemetry_snapshot.csv`:
 
 ```
 timestamp_ns,value,raw_hex
@@ -253,7 +253,7 @@ can-telem-cloud/
 │   └── db_watcher.[ch]   — SQLite DB watcher for TX signals
 ├── third_party/
 │   └── cJSON.[ch]        — JSON parser
-├── format.json           — (git submodule: sc-data-format)
+├── sc-data-format/       — git submodule containing format.json and format_exp.md
 ├── can_telem.conf.example
 └── Makefile
 ```

can_telem.conf.example

@@ -2,7 +2,7 @@
 # Keys are case-insensitive. CLI flags (-i, -f, -o) override these values.
 
 output_dir = /var/tmp/can_telem_logs
-format_file = ./format.json
+format_file = ./sc-data-format/format.json
 can_interface = can0
 
 # --- Optional: InfluxDB Cloud (HTTPS write API v2) ---