329 lines
7.7 KiB
Plaintext
329 lines
7.7 KiB
Plaintext
Great, thanks for sharing the gap analysis — this is actually a **very solid foundation** already. What’s missing now is not “features”, but **industrial-grade decisions, architectures, and concrete implementation patterns** that close those gaps in a *reliable, production-ready* way on **ESP32-S3 + ESP-IDF v5.4**.
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Below is a **structured proposal** that:
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* Closes the **critical & high gaps**
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* Uses **industrial best practices**
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* Stays **realistic for ESP32-S3**
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* Avoids “maker-grade” shortcuts
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I’ll group this by **system layer**, not by gap ID — that’s how real systems are engineered.
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---
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# 1️⃣ Communication Architecture (Industrial-Grade Proposal)
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## 1.1 Primary & Secondary Communication Stack
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### ✅ Final Decision
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| Role | Technology | Why (Industrial Rationale) |
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| ---------------------------------- | --------------------------- | -------------------------------------------- |
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| **Primary uplink** | **Wi-Fi 802.11n (2.4 GHz)** | Existing infra, high throughput for OTA |
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| **Peer-to-peer** | **ESP-NOW** | Deterministic, low latency, no AP dependency |
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| **Long-range fallback (optional)** | **LoRa (external module)** | Farm-scale resilience |
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> ⚠️ Zigbee on ESP32-S3 is **not industrial-mature** in ESP-IDF. ESP-NOW is far more reliable.
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---
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## 1.2 Application Protocol (This Is a Big Gap)
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### ❌ Avoid
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* Raw TCP sockets
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* Custom binary protocols without versioning
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### ✅ Use
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**MQTT over TLS 1.2**
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| Item | Decision |
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| ----------- | ------------------------------- |
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| Broker | Main Hub / Edge Gateway |
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| QoS | QoS 1 (at least once) |
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| Retain | Config topics only |
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| Payload | CBOR (binary, versioned) |
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| Topic model | `/farm/{site}/{house}/{node}/…` |
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📌 **Why MQTT?**
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* Store-and-forward
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* Built-in keepalive
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* Industrial tooling & monitoring
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* ESP-IDF native support (stable)
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---
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## 1.3 Heartbeat & Liveness (Formalized)
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```text
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Heartbeat interval: 10 s
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Missed heartbeats: 3 → offline
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Payload:
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{
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uptime,
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fw_version,
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free_heap,
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rssi,
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error_bitmap
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}
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```
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This directly feeds **predictive maintenance**.
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---
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# 2️⃣ Security Model (Non-Negotiable for Industrial Systems)
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## 2.1 Root of Trust (ESP32-S3 Strength)
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### Mandatory Features
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✅ Secure Boot V2
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✅ Flash Encryption
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✅ eFuse-based version anti-rollback
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> **No exceptions.** This is where “industrial” starts.
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---
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## 2.2 Device Identity & Authentication
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### Proposed Model (Used in Industry)
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| Item | Implementation |
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| ------------ | ------------------------------------- |
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| Identity | **Device-unique X.509 certificate** |
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| Private key | Stored in **eFuse / encrypted flash** |
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| Auth | **Mutual TLS (mTLS)** |
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| Provisioning | Factory or secure onboarding mode |
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📌 **Key insight**
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ESP32-S3 can handle **1 device cert perfectly**. Do **NOT** try to manage large cert chains on-device.
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---
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## 2.3 Key Lifecycle (Often Ignored — You Shouldn’t)
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| Phase | Mechanism |
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| ------------- | ------------------------- |
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| Manufacturing | Inject device cert + key |
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| Operation | TLS session keys only |
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| Rotation | Broker-side cert rotation |
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| Revocation | CRL or broker denylist |
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---
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# 3️⃣ OTA Strategy (Industrial Safe Updates)
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## 3.1 Partition Layout (Recommended)
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For **8MB flash**:
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```text
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bootloader
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partition_table
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factory (optional minimal rescue)
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ota_0 (3.5 MB)
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ota_1 (3.5 MB)
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nvs (64 KB, encrypted)
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phy_init
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coredump (64 KB)
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```
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---
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## 3.2 OTA Policy (Formal)
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| Step | Rule |
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| ------------ | --------------------------- |
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| Download | HTTPS / MQTT chunks |
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| Chunk size | 4096 bytes |
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| Integrity | SHA-256 full image |
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| Validation | Boot + health report |
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| Confirmation | App must confirm within 60s |
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| Failure | Automatic rollback |
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This closes **GAP-OTA-001/002/003** cleanly.
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---
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# 4️⃣ Sensor & Data Acquisition (Reliability Focus)
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## 4.1 Sensor Abstraction Layer (SAL)
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This is **critical** for long-term maintainability.
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```c
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sensor_read()
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sensor_calibrate()
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sensor_validate()
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sensor_health_check()
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```
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Each sensor driver **must implement** this interface.
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---
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## 4.2 Approved Industrial Sensor Strategy
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### Example (CO₂)
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| Primary | Backup |
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| ---------------- | ------------------ |
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| Sensirion SCD41 | Senseair S8 |
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| I²C | UART |
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| Self-calibration | Manual calibration |
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📌 **Rule:**
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Every *critical parameter* → **two qualified sensor options**
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---
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## 4.3 Warm-Up & Validity States
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Define sensor states explicitly:
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```text
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INIT → WARMUP → STABLE → DEGRADED → FAILED
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```
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Never publish raw values without a **validity flag**.
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---
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## 4.4 Filtering (Simple & Robust)
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**Recommended Default**
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* Median filter (N=5)
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* Rate-of-change limiter
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* Physical bounds check
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This avoids Kalman overengineering.
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---
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# 5️⃣ Data Persistence & Reliability
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## 5.1 SD Card (Industrial Pattern)
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| Aspect | Decision |
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| ------------- | -------------------------- |
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| FS | FAT32 |
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| Mode | SDMMC 4-bit |
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| Structure | Circular time-bucket files |
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| Write pattern | Append-only |
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| Flush | On power-loss interrupt |
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📌 **Never write small files frequently** → SD wear.
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---
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## 5.2 NVS Usage Rules
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| Data | Location |
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| ----------- | --------------------- |
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| Calibration | NVS (encrypted) |
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| Constants | NVS |
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| Counters | RAM + periodic commit |
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| Logs | SD / flash partition |
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---
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# 6️⃣ Diagnostics & Maintainability
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## 6.1 Diagnostic Code System
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**Proposed Format**
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```
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0xSCCC
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S = Severity (1–4)
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CCC = Subsystem code
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```
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| Range | Subsystem |
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| ------ | --------- |
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| 0x1xxx | DAQ |
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| 0x2xxx | COM |
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| 0x3xxx | SEC |
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| 0x4xxx | OTA |
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| 0x5xxx | HW |
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This allows **fleet analytics**, not just debugging.
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---
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## 6.2 Watchdogs (Layered)
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| Watchdog | Purpose |
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| ------------- | ------------------- |
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| Task WDT | Deadlocks |
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| Interrupt WDT | ISR hangs |
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| RTC WDT | Total system freeze |
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**10s / 3s / 30s** is a good baseline.
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---
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# 7️⃣ Power & Fault Handling (Farm Reality)
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## 7.1 Brownout & Power Loss
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| Feature | Implementation |
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| --------------- | -------------------- |
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| Brownout detect | 3.0 V |
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| ISR action | Flag + flush buffers |
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| Recovery | Clean reboot |
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Optional but recommended:
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* Supercap for 1–2 seconds
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* External RTC battery
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---
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# 8️⃣ GPIO & Hardware Discipline
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## Mandatory Rules
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❌ No strapping pins
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❌ No shared I²C without pull-up audit
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❌ No ADC2 for Wi-Fi systems
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Create **one canonical GPIO map document** — no exceptions.
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---
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# 9️⃣ What You Have vs What You Need
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### You already have:
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✅ Good functional coverage
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✅ Clear system intent
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✅ ESP32-S3 (excellent choice)
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### What this proposal adds:
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✅ Determinism
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✅ Security maturity
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✅ Fleet-scale maintainability
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✅ Industrial fault tolerance
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---
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## 🚜 Bottom Line
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Your system is **no longer a prototype** — it’s becoming an **industrial embedded product**.
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If you want, next we can:
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* Turn this into a **formal system architecture diagram**
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* Define a **FreeRTOS task model**
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* Design a **factory provisioning workflow**
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* Or map this directly to **ESP-IDF components & Kconfig options**
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Just tell me where you want to go next.
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