# MTG RFID Companion

A hand-held **Magic: The Gathering** companion built on an **ESP32-WROOM-32**. Tap an RFID/NFC-tagged card to a built-in reader and the device:

- renders the card's cover art and metadata on a **2.0" ST7789 TFT (240x320)**,
- flashes a **WS2812B Neopixel** in the card's mana color and plays a short **buzzer** chirp,
- keeps a **life counter** (20/40) you adjust with a rotary encoder,
- caches cards locally on **LittleFS** and refetches from the **Scryfall API** over Wi-Fi,
- runs a **SoftAP registration server** (`MTG-Companion`) so you can pair an unknown tag to a card name from your phone.

All code is **pure ESP-IDF v5.x (C) / FreeRTOS** — no Arduino.

---

## Features

| | |
| :--- | :--- |
| 🃏 RFID scanning | MFRC522, NTAG21x / MIFARE tags, 4- and 7-byte UIDs |
| 🖥️ Display | ST7789 240x320 RGB565, 5x7 text, scaled digits, streaming JPEG decode |
| 🌐 Network | Wi-Fi STA auto-connect, Scryfall HTTPS with local cache |
| 📡 Pairing | SoftAP `MTG-Companion` (192.168.4.1) web SPA for UID ↔ card name |
| 🔄 UX | EC11 rotary encoder, backlit life counter, mana-colored LED, audio cues |
| 💾 Storage | LittleFS `/spiffs` (~1.9MB) seeded with card mapping + example art |

---

## Hardware Requirements

- **ESP32-WROOM-32** dev board (4MB flash, no PSRAM required)
- **MFRC522** RFID reader (13.56 MHz, SPI)
- **ST7789** SPI TFT, 240x320 (e.g. common 2.0-2.4" breakout)
- **EC11** rotary encoder with push switch
- **WS2812B / Neopixel** (single LED)
- **Passive piezo buzzer**
- Antenna-friendly **NTAG213/NTAG215** stickers or MIFARE cards, ~3.3V–5V supply

---

## Wiring Guide

> **Do not change these GPIO assignments in code** unless you update both
> `main/hw_pins.h` and this table. The ST7789 and MFRC522 **share one SPI bus** (SPI2_HOST).

### Pin map

| Peripheral | Function | ESP32 GPIO | Notes |
| :--- | :--- | :---: | :--- |
| **Shared SPI** | SCK | **18** | SPI2_HOST (VSPI), 1 MHz modules |
| | MOSI | **23** | |
| | MISO | **19** | |
| **MFRC522** | SDA (CS) | **5** | dedicated chip select |
| | RST | **22** | hard reset |
| | 3.3V / GND | — | feed from board 3.3V rail |
| **ST7789** | CS | **15** | dedicated chip select |
| | DC (A0) | **2** | data/command |
| | RST | **4** | panel reset |
| | LED | 3.3V or 5V | optional backlight pin |
| **EC11** | CLK | **32** | interrupt input, pull-up |
| | DT | **33** | quadrature B |
| | SW | **25** | button, active low, pull-up |
| **WS2812B** | DIN | **27** | RMT Tx; supply 5V/VDD, GND common |
| **Buzzer** | SIG | **14** | LEDC PWM |

### Suggested breadboard layout

```
        ESP32-WROOM-32
  ┌────────────────────────────┐
  │ 3V3  18 ──── SCK ───────┤ MFRC522  5 ── SDA(CS)  22 ── RST
  │ GND  23 ──── MOSI ──────┤ (SPI)    3V3/GND
  │       19 ──── MISO ─────┤
  │       15 ──── CS ───────┤ ST7789   2 ── DC  4 ── RST
  │       4 ─────────────────┤ (SPI)
  │       32 ── CLK ─────────┤ EC11     33 ── DT  25 ── SW/GND
  │       27 ── Din ─────────┤ WS2812B  (5V + GND)
  │       14 ── SIG ─────────┤ Buzzer   (GND)
  └────────────────────────────┘
```

- Keep SPI signal runs short (< 10 cm) for reliable 20 MHz display transfers.
- NTAG213/215 FPC stickers need to sit flat and close to the MFRC522 antenna.
- The **WS2812B** draws up to ~60 mA; power it from the 5V rail, never from a GPIO.

---

## Getting Started

### 1. Toolchain

Install ESP-IDF **v5.5** (any 5.x works): https://docs.espressif.com/projects/esp-idf/en/latest/esp32/get-started/

Verify:

```powershell
# Windows (Espressif "ESP-IDF 5.5 PowerShell" terminal)
. C:\Espressif\Initialize-Idf.ps1        # or: . $IDF_PATH\export.ps1
idf.py --version
```

### 2. Build

```powershell
idf.py set-target esp32
idf.py build
```

The custom partition table (`partitions.csv`) reserves:

| Offset | Size | Subtype | Purpose |
| :--- | :--- | :--- | :--- |
| 0x10000 | 2 MB | app/factory | firmware |
| 0x210000 | ~1.9 MB | data/littlefs | `/spiffs` cache (seeded from `storage/`) |

### 3. Configure Wi-Fi

Two equivalent ways:

```powershell
# a) interactive menu (recommended)
idf.py menuconfig        # -> "MTG RFID Companion" -> SSID + password

# b) edit the preset file directly
#    sdkconfig.defaults.esp32
```

Leaving the SSID empty (or keeping the `YOUR_...` placeholders) disables station
mode — the SoftAP pairing server still runs, so you can use the device
without a home network.

### 4. Flash & watch

```powershell
idf.py -p COMx flash monitor      # COMx = your serial port
```

Expected boot log if everything is wired right:

```
I storage: LittleFS mounted at /spiffs: <size> bytes total ...
I storage: boot_count read back = 1 (persistence across reboots OK)
I rfid:    RC522 polling task pinned to Core 0
I display: ST7789 240x320 ready ...
I web:     SoftAP 'MTG-Companion' at 192.168.4.1, web server ready
I ui:      UI task on core 1
```

---

## Usage

### Scan a card
Place a tagged card on the reader:
1. **Mapped UID** → chirp, mana-colored LED flash, then the card view (cover art + name/type/P·T/price/mana).
2. **Unknown UID** → registration screen with the pairing address.

### Life counter
Press the encoder button to toggle **SCANNER ↔ LIFE_COUNTER**. Rotate to adjust
(20/40 preset or whatever you last set; press again to reset to the preset).

### Web pairing (registration mode)
1. Connect your phone to the `MTG-Companion` access point.
2. Open `http://192.168.4.1`.
3. Scan an unmapped card — the UID appears in the page.
4. Type / pick a Scryfall-autocomplete name → **Pair UID with card**.
5. The mapping persists to `/spiffs/mappings.json` and the card is fetched & cached.

---

## Storage Layout (`/spiffs`)

```
/spiffs/
├── mappings.json              UID -> Card Name map
├── cards/
│   ├── sample.json            example metadata
│   ├── sample.jpg             example cover art (baked into flash image)
│   ├── <UID>.json             Scryfall metadata cache
│   └── <UID>.jpg              cached cover art
```

The `storage/` folder is compiled into the LittleFS partition image at build
time (`littlefs_create_partition_image`), so a fresh flash already contains
`mappings.json` and the example art.

---

## Troubleshooting

| Symptom | Fix |
| :--- | :--- |
| Display = black / garbage | Check CS/DC/RST wiring; try toggling `esp_lcd_panel_invert_color` and `LCD_RGB_ELEMENT_ORDER_*` in `display_manager.c` |
| Colors inverted | Same toggle as above — panel clones differ |
| No UID printed on scan | Verify MFRC522 wiring, tag type (ISO14443A), antenna positioning; confirm `rfid: RC522 polling task pinned to Core 0` in the log |
| Wi-Fi never connects | Re-run `idf.py menuconfig`, confirm you replaced the `YOUR_...` placeholders |
| Can't reach 192.168.4.1 | Ensure your phone joined `MTG-Companion`, not a cached network |
| Card renders but no art | Card not cached yet — check `scryfall` log lines; art downloads are best-effort |
| App grows near 2MB | mbedTLS + HTTP pulls are large; if needed, enable `CONFIG_MBEDTLS_CERTIFICATE_BUNDLE` (smaller) |

---

## Project Layout

```
├── CMakeLists.txt              top-level; bakes LittleFS storage image
├── partitions.csv              custom partition table
├── sdkconfig.defaults          shared ESP32 defaults
├── sdkconfig.defaults.esp32    Wi-Fi credential preset (edit me)
├── storage/                    files pre-seeded into /spiffs
├── tools/                      host-side helpers (sample JPEG generator)
└── main/
    ├── hw_pins.h               GPIO assignments (authoritative)
    ├── spi_bus_manager.c       shared SPI2_HOST bus
    ├── storage_manager.c       LittleFS mount + JSON helpers
    ├── rfid_manager.c          MFRC522 / Core 0 polling
    ├── display_manager.c       ST7789 + fonts + streaming JPEG
    ├── ui_task.c               state machine + screens (Core 1)
    ├── wifi_manager.c          STA connect/reconnect
    ├── scryfall_client.c       Scryfall HTTPS + cache (net_task)
    ├── web_server.c            SoftAP pairing server
    ├── encoder.c               EC11 ISR decode
    ├── led_manager.c           WS2812B RMT
    ├── buzzer.c                LEDC PWM tones
    └── app_state.c             shared app/life-counter state
```

See `AGENTS.md` for the detailed architecture, core split, and coding
conventions used across this repository.