# ESP32 Build Tools for Spider Runtime

Build system for compiling the Spider Runtime for the ESP32
microcontroller using the Espressif Xtensa toolchain.

---

## Requirements

- [ESP-IDF v5.x](https://dl.espressif.com/dl/esp-idf/) installed
- MSYS2 or any Unix-like shell
- `spider-runtime` repository cloned at the same level as this repo

Expected folder structure:
```
Internship/
    spider-runtime/
    spider-micro-buildtools/
        esp32/   ← you are here
```

Add the Xtensa toolchain to your PATH before building:
```bash
export PATH=$PATH:/c/Espressif/tools/xtensa-esp-elf/<version>/xtensa-esp-elf/bin
```

---

## Files

| File | Description |
|------|-------------|
| `Makefile` | Build recipe for ESP32 using `xtensa-esp-elf-g++` |
| `gen_makefile.py` | Regenerates the Makefile (run if Makefile gets corrupted) |
| `main_esp32.cpp` | ESP32 entry point, replaces the desktop `main()` |

---

## Build
```bash
make
```

Output: `out/spider_esp32.elf`

To clean and rebuild from scratch:
```bash
make cleaner
make
```

---

## Flash to ESP32

**Step 1 — Convert to flashable binary:**
```bash
xtensa-esp-elf-objcopy -O binary out/spider_esp32.elf out/spider_esp32.bin
```

**Step 2 — Connect your ESP32 via USB and find the COM port**

On Windows, check Device Manager under "Ports (COM & LPT)".

**Step 3 — Flash:**
```bash
esptool.py --chip esp32 --port COM3 --baud 115200 write_flash 0x1000 out/spider_esp32.bin
```

Replace `COM3` with your actual port.

---

## Compiler Flags

| Flag | Purpose |
|------|---------|
| `-DESP32` | Activates ESP32 detection in `distro_mcu.hpp` |
| `-DSPIDER_DISTRO_MICRO` | Enables microcontroller mode |
| `-DSPIDER_OS_NONE` | Declares bare-metal, no OS |
| `-mlongcalls` | Required for Xtensa memory layout |
| `-fno-exceptions -fno-rtti` | Disable unavailable C++ features |
| `-O0` | No optimizations, faster development builds |