37 lines
916 B
Markdown
37 lines
916 B
Markdown
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## Exercise 04: SD Card
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This exercise loops forever. Each cycle:
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1. Prints `Sleeping 10 seconds` and waits 10 seconds.
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2. Detects and mounts the SD card.
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3. Prints card and filesystem info (type/size/used).
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4. Writes `/Exercise_04_test.txt` with:
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- `This is a test`
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5. Ensures nested directories exist:
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- `/test/testsub1/testsubsub1`
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6. Writes nested file:
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- `/test/testsub1/testsubsub1/Exercise_04_test.txt`
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7. If either target file already exists, prints warning, erases it, then recreates it.
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8. Demonstrates permission behavior:
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- Notes FAT does not provide Unix `chmod/chown`.
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- Shows access behavior via `FILE_READ` vs `FILE_WRITE` modes.
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## Build
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```bash
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source /home/jlpoole/rnsenv/bin/activate
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pio run -e node_a
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```
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## Upload
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```bash
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source /home/jlpoole/rnsenv/bin/activate
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pio run -e node_a -t upload --upload-port /dev/ttyACM0
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```
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## Monitor
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```bash
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screen /dev/ttyACM0 115200
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```
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