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Phase 8 — SD log

Append CSV samples to the 3V3 6-pin TF/SPI mini reader while the Phase 7 climate UI keeps updating. Shared SPI clock/MOSI with the TFT; dedicated SD CS and MISO.

Firmware

Changed. New folder firmware/08-sd-log/ · src/main.cpp. Uses SdFat on the shared SPI bus (not the AVR arduino-libraries/SD package).

Behaviour Value
TFT UI same Climate screen @ ~1 Hz
CSV path /climate.csv
Append interval 60 s (LOG_PERIOD_MS — raise toward 300000 for 5 min)
Timestamp uptime_ms (no RTC in v1)

Preconditions

  • Checkpoint 7 passed (TFT live + serial match)
  • microSD already FAT32 on the host (Prerequisites §4) — label CLIMATE on this bench
  • Card seated in the Temu 6-pin reader
  • Unplug USB while seating SD jumpers

8.1 SD wires

Phase 8 - microSD SPI

This bench silk (header order): 3V3 · CS · MOSI · CLK · MISO · GND. Some boards print M0SI / MIS0 (zero for letter O).

S3 Module silk
3V3 3V3
GPIO13 CS
GPIO11 MOSI (already on TFT SDA)
GPIO12 CLK (same as SCK; already on TFT SCL)
GPIO14 MISO
GND GND

Match by label, not assumed left-to-right on a different pack. Never share CS with TFT CS (GPIO10). Power from 3V3 only.

8.2 Flash

Stop any serial monitor on COM first.

cd firmware/08-sd-log
pio run -e esp32-s3-n16r8 -t upload --upload-port /dev/ttyACM0

Connected to ESP32-S3 on /dev/ttyACM0:
…
Hash of data verified.
Hard resetting via RTS pin...
========================= [SUCCESS] Took 19.44 seconds =========================

pio device monitor -b 115200 --port /dev/ttyACM0

weather sd-log — phase 8
I2C SDA=8 SCL=18  TFT CS=10  SD CS=13 MISO=14
UI ~1 Hz; CSV append every 60 s -> /climate.csv
SD ready
UI live
temp_c=25.48  humidity=85.0  pressure_hpa=1010.28
sd append /climate.csv uptime_ms=1205

This bench: FAT32 card mounts; first CSV append right after boot, then about every 60 s.

Example row

uptime_ms,temp_c,humidity,pressure_hpa
60012,25.40,85.0,1010.30

8.3 Validate

  1. TFT Climate UI still updates (~1 Hz).
  2. Serial shows SD ready, then sd append /climate.csv … about once a minute.
  3. Power down, pull the card, open /climate.csv on the host — header + growing rows.

8.4 If SD fails

  • SD begin failed → reseat card; re-check FAT32 on the host (Prerequisites §4); CS is GPIO13 not TFT CS
  • Host reader shows SIZE 0B → card not detected; try another card/reader before blaming SPI
  • Reader stays cool on 3V3 (5V kills many modules)
  • MISO must be GPIO14 (TFT does not need MISO; the card does)
  • Shared CLK/MOSI still seated to the TFT from Phase 6
  • Try a shorter CS/MISO jumper; another card

UI-only without a card is OK for bring-up — fix the reader before calling the checkpoint done.

Checkpoint 8

  • [x] File /climate.csv grows while powered (sd append on serial)
  • [ ] CSV opens cleanly on the host (header + rows) — pull card and confirm once
  • [x] TFT UI still live with SPI shared (Phase 9 bench photo)
  • [x] Logged in lab-log.md

Stop here until checkpoint passes.

Next: Phase 9 — TFT views