RTC keeps time between POWER OFF & ON, SD Card at start still needs work -- if card is in the slot, it is not readable until it is pulled on and then inserted.

exercises/05_SD_Card_Watcher/README.md

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+## Exercise 05: SD Card Watcher
+
+This exercise continuously watches SD card presence and prints state-change events.
+
+Watcher behavior:
+
+1. Initializes PMU and enables SD power rail (AXP2101 BLDO1).
+2. Polls for card changes with debounced state transitions.
+3. Emits events only on change:
+   - `EVENT: card inserted/mounted`
+   - `EVENT: card removed/unavailable`
+   - `EVENT: no card detected`
+4. On mount event, prints card info and runs SD write workflow.
+5. Every 15 seconds while mounted, runs a periodic write/permission check.
+6. Uses fast preferred probe (`HSPI @ 400k`) and occasional full fallback scan.
+
+Files used in this exercise:
+- `/Exercise_05_test.txt`
+- `/test/testsub1/testsubsub1/Exercise_05_test.txt`
+
+## Build
+
+```bash
+source /home/jlpoole/rnsenv/bin/activate
+pio run -e node_a
+```
+
+## Upload
+
+```bash
+source /home/jlpoole/rnsenv/bin/activate
+pio run -e node_a -t upload --upload-port /dev/ttyACM0
+```
+
+## Monitor
+
+```bash
+screen /dev/ttyACM0 115200
+```