diff --git a/docs/wiring-diagram.md b/docs/wiring-diagram.md
index 61736f7..b5fb999 100644
--- a/docs/wiring-diagram.md
+++ b/docs/wiring-diagram.md
@@ -10,9 +10,11 @@
 │  USB-C ──── STM32 CDC (/dev/stm32-bridge, 921600 baud)            │
 │  USB-A1 ─── RealSense D435i (USB 3.1)                             │
 │  USB-A2 ─── RPLIDAR A1M8 (via CP2102 adapter, 115200)             │
+│  USB-C* ─── SIM7600A 4G/LTE modem (ttyUSB0-2, AT cmds + PPP)     │
 │  CSI-A ──── ArduCam adapter → 2× IMX219 (front + left)            │
 │  CSI-B ──── ArduCam adapter → 2× IMX219 (rear + right)            │
 │  M.2 ───── 1TB NVMe SSD                                            │
+│  40-pin ─── ReSpeaker 2-Mic HAT (I2S + I2C, WM8960 codec)         │
 │  Pin 8 ──┐                                                         │
 │  Pin 10 ─┤ UART fallback to FC (ttyTHS0, 921600)                  │
 │  Pin 6 ──┘ GND                                                     │
@@ -149,6 +151,59 @@ BATTERY (36V) ──┬── Hoverboard ESC (36V direct)
 | USB CDC | USB-C | 921600 | Jetson primary | `/dev/stm32-bridge` |
 
 
+### 7. ReSpeaker 2-Mic HAT (on Orin 40-pin header)
+
+| Orin Pin | Signal | Function |
+|----------|--------|----------|
+| Pin 12 (GPIO 18) | I2S BCLK | Audio bit clock |
+| Pin 35 (GPIO 19) | I2S LRCLK | Audio left/right clock |
+| Pin 38 (GPIO 20) | I2S DIN | Audio data in (from mics) |
+| Pin 40 (GPIO 21) | I2S DOUT | Audio data out (to speaker) |
+| Pin 3 (GPIO 2) | I2C SDA | WM8960 codec control (i2c-7) |
+| Pin 5 (GPIO 3) | I2C SCL | WM8960 codec control (i2c-7) |
+| Pin 32 (GPIO 12) | GPIO | Button input |
+| Pin 11 (GPIO 17) | GPIO | RGB LED (APA102 data) |
+| Pin 2, 4 | 5V | Power |
+| Pin 6, 9 | GND | Ground |
+
+- **Codec:** Wolfson WM8960 (I2C addr 0x1A)
+- **Mics:** 2× MEMS (left + right) — basic stereo / sound localization
+- **Speaker:** 3W class-D amp output (JST connector)
+- **Headset:** 3.5mm TRRS jack
+- **Requires:** WM8960 device tree overlay for Jetson (community port)
+- **Use:** Voice commands (faster-whisper), wake word (openWakeWord), audio feedback, status announcements
+
+### 8. SIM7600A 4G/LTE HAT (via USB)
+
+| Connection | Detail |
+|-----------|--------|
+| Interface | USB (micro-B on HAT → USB-A/C on Orin) |
+| Device nodes | `/dev/ttyUSB0` (AT), `/dev/ttyUSB1` (PPP/data), `/dev/ttyUSB2` (GPS NMEA) |
+| Power | 5V from USB or separate 5V supply (peak 2A during TX) |
+| SIM | Nano-SIM slot on HAT |
+| Antenna | 4G LTE + GPS/GNSS (external SMA antennas — mount high on chassis) |
+
+- **Data:** PPP or QMI for internet connectivity
+- **GPS/GNSS:** Built-in receiver, NMEA sentences on ttyUSB2 — outdoor positioning
+- **AT commands:** `AT+CGPS=1` (enable GPS), `AT+CGPSINFO` (get fix)
+- **Connected via USB** (not 40-pin) — avoids UART conflict with FC fallback, flexible antenna placement
+- **Use:** Remote telemetry, 4G connectivity outdoors, GPS positioning, remote SSH/control
+
+### 9. Power Budget (USB)
+
+| Device | Interface | Power Draw |
+|--------|-----------|------------|
+| STM32 FC (CDC) | USB-C | ~0.5W (data only, FC on 5V bus) |
+| RealSense D435i | USB-A | ~1.5W (3.5W peak) |
+| RPLIDAR A1M8 | USB-A | ~2.6W (motor on) |
+| SIM7600A | USB | ~1W idle, 3W TX peak |
+| ReSpeaker HAT | 40-pin | ~0.5W |
+| **Total USB** | | **~6W typical, ~10W peak** |
+
+Orin Nano Super delivers up to 25W — USB peripherals are well within budget.
+
+---
+
 ## Data Flow
 
 ```
@@ -178,6 +233,13 @@ BATTERY (36V) ──┬── Hoverboard ESC (36V direct)
 │                │          │                     │
 │ L motor  R motor│         │  SLAM / Nav2 / AI  │
 │    🛞      🛞   │         │  Person following   │
-└────────────────┘          │  cmd_vel → FC       │
-                            └───────────────────┘
+└────────────────┘          │  Voice commands     │
+                            │  4G telemetry       │
+                            └──┬──────────┬───────┘
+                               │          │
+                    ┌──────────▼─┐   ┌────▼──────────┐
+                    │ ReSpeaker  │   │  SIM7600A     │
+                    │ 2-Mic HAT  │   │  4G/LTE + GPS │
+                    │ 🎤 🔊      │   │  📡 🛰️        │
+                    └────────────┘   └───────────────┘
 ```