275 lines
11 KiB
Markdown
275 lines
11 KiB
Markdown
# SC-F001 Firmware
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**Solar-powered automated crop harvesting robot** built on the ESP32. Drives a carriage horizontally via a drive motor, lifts/lowers a cutting head via a jack motor, with an auxiliary "fluffer" motor always running during operation. The firmware handles motor sequencing, safety interlocks, remote control, data logging, and a WiFi web interface.
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**Primary operational cycle:** Idle → Move Start Delay → Jack Up → Drive → Jack Down → Idle
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---
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## Hardware Platform
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**MCU:** ESP32 (Xtensa dual-core), ESP-IDF framework
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**GPIO Map:**
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| GPIO | Function |
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|------|----------|
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| 13 | Button interrupt (active low, pull-up) |
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| 14 | Jack position sensor / encoder |
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| 16 | Drive encoder |
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| 19 | Aux sensor 2 (reserved) |
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| 21/22 | I2C SDA/SCL (400kHz) → TCA9555 I/O expander |
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| 25 | 433MHz RF receiver (RMT input) |
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| 26 | Solar charger bulk enable (RTC GPIO) |
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| 27 | Safety sensor (active low) |
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| 32/33 | External 32.768 kHz RTC crystal (on PCB, not used — see RTC section) |
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| 36 (VP) | ADC: drive current sense |
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| 39 (VN) | ADC: battery voltage |
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| 34 | ADC: jack current sense |
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| 35 | ADC: aux current sense |
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**TCA9555 (I2C at 0x21):**
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- Port 0 (input): 2 physical buttons + 2 additional inputs
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- Port 1 (output): 3× H-bridge relay pairs (DRIVE, JACK, AUX) + LEDs
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**Motor / Bridge Specs:**
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- `BRIDGE_DRIVE` — 100A max, ACS37220 sense chip (13.2 mV/A, inverted polarity)
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- `BRIDGE_JACK` — 30A max, ACS37042 sense chip (44 mV/A)
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- `BRIDGE_AUX` — 30A max, ACS37042 sense chip (44 mV/A)
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---
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## Software Architecture
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```
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app_main()
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├── rtc_xtal_init() Button GPIO setup
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├── i2c_init() TCA9555 init (relays off, LEDs off)
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├── adc_init() ADC1 calibration (12dB attenuation, line-fit)
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├── storage_init() Flash params
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├── log_init() Circular log buffer
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├── solar_run_fsm() (called in main loop too)
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├── uart_init() Serial JSON API task
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├── sensors_init() GPIO ISR setup for sensors/encoders
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├── fsm_init() Control FSM task (priority 10, 20ms tick)
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├── rf_433_init() 433MHz RMT receiver task
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├── bt_hid_init() BLE HID host scanner task
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└── webserver_init() WiFi softAP + HTTP + mDNS + DNS
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Main loop (50ms):
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i2c_poll_buttons()
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fsm_request() based on button events
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solar_run_fsm()
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drive_leds() status animation
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rtc_check_shutdown_timer() → soft idle on inactivity (180s)
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```
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**FreeRTOS Tasks:**
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| Task | Created by | Priority | Tick | Purpose |
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|------|-----------|----------|------|---------|
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| `app_main` (main loop) | system | 1 (default) | 50ms | Button polling, LED animation, solar FSM, shutdown timer |
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| `control_task` | `fsm_init()` | 10 | 20ms | FSM state machine, relay control, ADC current monitoring, e-fuse |
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| UART task | `uart_init()` | default | event-driven | Serial JSON command processing |
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| RF 433 task | `rf_433_init()` | default | event-driven | RMT receive + keycode matching |
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| BT HID task | `bt_hid_init()` | default | event-driven | BLE HID host scanning + button mapping |
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| httpd workers | `webserver_init()` | default | event-driven | HTTP request handling (multiple workers spawned by esp_http_server) |
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---
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## Key Files
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| File | Purpose |
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|------|---------|
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| `main.c` | Entry point, 50ms main loop, factory reset, LED animation |
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| `control_fsm.c/h` | State machine, relay control, current monitoring, calibration |
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| `power_mgmt.c/h` | ADC reading, e-fuse thermal algorithm, battery voltage |
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| `sensors.c/h` | GPIO ISR-based sensor debouncing, encoder counters |
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| `i2c.c/h` | TCA9555 relay/LED/button control |
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| `storage.c/h` | 48-param NVM table + circular binary log buffer |
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| `comms.c/h` | Unified GET/POST JSON API (shared by HTTP and UART) |
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| `webserver.c/h` | WiFi softAP, HTTP server, embedded gzip webpage |
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| `uart_comms.c/h` | Serial JSON interface (115200 8N1) |
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| `rf_433.c/h` | 433MHz OOK receiver, keycode learn/match |
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| `bt_hid.c/h` | BLE HID host, media remote button mapping |
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| `rtc.c/h` | Unix time, harvest alarms, soft idle, inactivity timer |
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| `solar.c/h` | Simple FLOAT/BULK solar charge state machine |
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| `sc_err.h` | Error code definitions |
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| `log_test.c/h` | Flash log unit tests |
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| `hard_ui.c` | Legacy LCD code (unused/obsolete) |
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---
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## Control FSM States
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```
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STATE_IDLE
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STATE_MOVE_START_DELAY (1s)
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STATE_JACK_UP_START (detect current spike → jack engaged)
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STATE_JACK_UP (continue until timer/e-fuse)
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STATE_DRIVE_START_DELAY (1s)
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STATE_DRIVE (encoder-based distance control)
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STATE_DRIVE_END_DELAY (1s)
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STATE_JACK_DOWN (reverse until e-fuse/sensor)
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→ back to STATE_IDLE
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STATE_UNDO_JACK_START (emergency: reverse jack, run until e-fuse/sensor)
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→ back to STATE_IDLE
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CAL_JACK_DELAY / CAL_JACK_MOVE (jack calibration sequence)
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CAL_DRIVE_DELAY / CAL_DRIVE_MOVE (drive calibration sequence)
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```
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**Guards before START:**
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- Remaining distance > 0 (leash protection)
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- Battery V ≥ `LOW_PROTECTION_V` (default 10V)
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- Safety sensor active (debounced stable)
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- All e-fuses not tripped
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**FSM Loop (20ms tick in `control_task()`):**
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1. `process_bridge_current()` — ADC → EMA → auto-zero → e-fuse
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2. `process_battery_voltage()` — ADC → EMA
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3. `sensors_check()` — drain ISR queue, update counters/debounce
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4. State machine transitions (timer + sensor + efuse checks)
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5. `drive_relays()` — write relay output from current state
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6. `send_fsm_log()` — 39-byte timestamped entry to flash
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---
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## E-Fuse Algorithm (`power_mgmt.c`)
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Per bridge, each 20ms tick:
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1. Raw ADC → EMA filter (α = `ADC_ALPHA_ISENS`)
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2. Auto-zero: learn zero offset when motor is off + grace period expired
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3. Grace period: 250ms after relay closes (ignores startup inrush)
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4. **Instant trip:** I ≥ `EFUSE_KINST` × I_nom (default 2×)
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5. **Thermal trip:** heat accumulates as I²·Δt; dissipates at τ_cool rate
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6. **Auto-reset:** after `EFUSE_TCOOL` seconds of cooling (default 5s)
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---
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## Safety Sensor Debouncing (Asymmetric)
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```
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LOW (safe): 1000ms make time → slow to declare safe (SAFETY_MAKE_US)
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HIGH (break): 300ms break time → fast to kill operation (SAFETY_BREAK_US)
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```
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Safety break → immediate `STATE_UNDO_JACK_START`.
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---
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## Communication Interfaces
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### WiFi (softAP)
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- SSID/password/channel configurable via params (`WIFI_SSID`, `WIFI_PASS`, `WIFI_CHANNEL`)
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- mDNS hostname: `sc.local`
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- Captive portal DNS: all queries → 192.168.4.1
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- HTTP port 80
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### HTTP API (port 80)
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| Endpoint | Method | Description |
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|----------|--------|-------------|
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| `/` | GET | Embedded gzip HTML webpage |
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| `/get` | GET | JSON system status |
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| `/post` | POST | JSON commands + parameter updates |
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| `/log` | GET | Binary log download (4B JSON len + JSON + 8B offsets + log data) |
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| `/ota` | POST | Firmware update upload |
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### UART (115200 8N1)
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- `GET` → same as HTTP GET /get
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- `POST: {json}` → same as HTTP POST /post
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- `RTCDEBUG` → dump RTC timekeeping state (time, backup, sleep entry, clock source)
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- `HELP` → command reference
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- Shares `comms_handle_get()` / `comms_handle_post()` with HTTP
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### 433MHz RF (GPIO25, RMT)
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- 24-bit OOK codes (P_HIGH≈1040µs, P_LOW≈340µs, margin 70µs)
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- 8 stored keycodes → FSM_OVERRIDE_* commands
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- Learn mode: capture next RX → temp buffer → user commits via web
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### Bluetooth HID Host
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- Scans for BLE HID devices (service UUID 0x1812)
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- Tries saved BDA first, then scans for best RSSI
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- Button mapping:
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- VOL_UP → Jack Up (override pulse)
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- VOL_DOWN → Jack Down
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- PREV → Drive Reverse
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- NEXT → Drive Forward
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---
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## Storage Layout
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**Flash partition "storage":**
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```
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0x0000 – 0x0FFF Parameters (4 sectors, CRC32-protected, 48 params)
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0x1000 – end Circular log buffer (head/tail tracked)
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```
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**Log entry format (39 bytes typical):**
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```
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[0:8] Timestamp ms (u64 BE)
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[8:12] Battery voltage (f32)
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[12:16] Drive current (f32)
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[16:20] Jack current (f32)
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[20:24] Aux current (f32)
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[24:26] Drive encoder count (i16)
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[26] Sensor states (packed)
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[27:31] Drive heat (f32)
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[31:35] Jack heat (f32)
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[35:39] Aux heat (f32)
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```
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**Key Parameters:**
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- Motion: `DRIVE_DIST`, `JACK_DIST`, `DRIVE_KT`, `JACK_KT`, `DRIVE_KE`
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- E-fuse: `EFUSE_INOM_1/2/3`, `EFUSE_HEAT_THRESH`, `EFUSE_KINST`, `EFUSE_TCOOL`
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- Safety: `SAFETY_BREAK_US`, `SAFETY_MAKE_US`, `LOW_PROTECTION_V`
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- RF: `KEYCODE_0` … `KEYCODE_7`
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- WiFi: `WIFI_SSID`, `WIFI_PASS`, `WIFI_CHANNEL`
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- Schedule: `NUM_MOVES`, `MOVE_START`, `MOVE_END` (seconds-since-midnight)
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---
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## RTC & Timekeeping
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**Time source:** `esp_timer` (40 MHz APB crystal, ~20 ppm accuracy). The external 32.768 kHz crystal on GPIO32/33 is present on the PCB but **not used** — deep sleep is disabled (soft idle instead), so RTC slow clock accuracy is irrelevant. The RTC slow clock uses the default internal RC oscillator.
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**`rtc_xtal_init()` in `rtc.c`:** Configures the button GPIO (GPIO13); no crystal bootstrap or sleep wakeup sources.
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**Time persistence across resets:** `sync_unix_us` and `sync_rtc_us` are `RTC_DATA_ATTR` (survive software resets — panics, WDT). On restart, `rtc_restore_time()` recovers time via the RTC hardware counter (which runs in the RTC domain and survives resets). RC oscillator drift (~±5%) is negligible over a <30s crash restart (~1.5s worst case).
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**Diagnosing time issues:** Run `RTCDEBUG` over UART. Reports current time, sync time, elapsed since sync, next alarm, uptime, and soft idle state.
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---
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## Power Management
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- **Battery voltage:** GPIO39, divider → `V = raw × V_SENS_K + V_SENS_OFFSET` (defaults: K=0.00766̄, offset=0.4)
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- **Solar charger:** GPIO26 (RTC hold) — FLOAT/BULK FSM, bulk for 20s when V < 5V for 5s
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- **Inactivity shutdown:** 180s → **soft idle** (WiFi/BT off, LEDs off — not deep sleep). Button press exits soft idle.
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- **RTC_DATA_ATTR:** Sync timestamps, alarm times, charge state — survive software resets (panics, WDT)
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---
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## Error Codes (`sc_err.h`)
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```c
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SC_ERR_EFUSE_TRIP_1 = 0x201 // Drive overcurrent/overheat
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SC_ERR_EFUSE_TRIP_2 = 0x202 // Jack
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SC_ERR_EFUSE_TRIP_3 = 0x203 // Aux
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SC_ERR_SAFETY_TRIP = 0x210 // Safety sensor break
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SC_ERR_LEASH_HIT = 0x211 // Distance limit reached
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SC_ERR_RTC_NOT_SET = 0x220 // Clock not synchronized
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SC_ERR_LOW_BATTERY = 0x230 // Voltage below threshold
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```
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---
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## Build System
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- **Framework:** ESP-IDF (>=5.0)
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- **Component deps** (`main/idf_component.yml`): `espressif/mdns ~1.9.1`
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- **IDF requires:** `driver`, `esp_http_server`, `esp_netif`, `lwip`, `json`, `esp_timer`, `esp_adc`, `app_update`, `esp_wifi`, `nvs_flash`, `mdns`, `bt`, `esp_hid`
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- **Webpage:** `webpage.html` → `webpage_compile.py` → `webpage_gzip.h` (embedded gzip binary). **Must re-run `webpage_compile.py` after any HTML edit before building.**
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- **Version:** `version.h.in` filled by CMake from git tags → `FIRMWARE_VERSION`, `BUILD_DATE`
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- **Factory reset:** Hold GPIO13 button on cold boot → full parameter + log erase
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