MIA PCB v1
A custom USB-A form-factor board designed to plug directly into a target machine and disappear — it looks like a USB drive.
Design goals
- USB-A plug built into the PCB edge (gold-plated contacts) — plugs directly into any USB-A port
- ESP32-S3-WROOM-1 (N16R8) for processing and native USB HID
- E22-900M30S for long-range LoRa comms
- MicroSD slot for payload storage
- Compact enough to leave in a machine without drawing attention
Current status
v1 has a hardware bug — A routing error on v1 boards prevents the E22 LoRa module from initializing. v2 corrects the routing error and adds BOOT/RESET buttons + an LED.
Pin mapping
| Signal | ESP32 GPIO |
|---|---|
| LORA_CS (NSS) | 8 |
| LORA_RST | 12 |
| LORA_BUSY | 13 |
| LORA_DIO1 | 14 |
| LORA_SCK | 9 |
| LORA_MOSI | 10 |
| LORA_MISO | 11 |
| SD_CS | 4 |
| SD_DETECT | 5 (optional) |
| USB_D- | 19 (native) |
| USB_D+ | 20 (native) |
Flashing v1 boards
v1 has no BOOT/RESET buttons. To enter bootloader mode:
- Bridge GPIO0 (physical pad 10 on the WROOM-1) to GND while powering on
- Release after the board enumerates
- Run
pio run -e mia_pcb -t upload
Native USB auto-reset works once firmware is installed.