LifeSize PTZ Camera VISCA-to-IR Bridge

A MicroPython-based bridge that receives standard VISCA-over-IP commands and translates them to IR signals for controlling a LifeSize 10x PTZ camera.

Architecture

This project uses a two-Pico design for reliable IR timing:

┌──────────────┐         ┌──────────────┐         ┌──────────────┐
│     PTZ      │  UDP    │  VISCA Pico  │  UART   │   IR Pico    │   IR    ┌────────┐
│  Controller  │────────►│   (W5500)    │────────►│  (38kHz PWM) │────────►│ Camera │
│  (PC/iPad)   │  52381  │  pico_visca/ │ 115200  │   pico_ir/   │         └────────┘
└──────────────┘         └──────────────┘         └──────────────┘

Why two Picos? The LifeSize camera requires precise 57.325ms gaps between IR frames for smooth movement. A dedicated IR Pico handles only timing-critical transmission, while the VISCA Pico handles network operations.

Hardware Requirements

VISCA Pico (Network Handler)

• Raspberry Pi Pico 2W
• W5500 Ethernet Module (SPI)
• 5V Relay Module (optional, for camera power)

IR Pico (IR Transmitter)

• Raspberry Pi Pico 2W
• IR LED with driver circuit (38kHz)

Connections Between Picos

VISCA Pico	IR Pico	Function
GP0 (TX)	GP1 (RX)	UART TX
GP1 (RX)	GP0 (TX)	UART RX
GND	GND	Ground

Pin Configuration

VISCA Pico

Function	GPIO
SPI SCK	GP2
SPI MOSI	GP3
SPI MISO	GP4
SPI CS	GP5
W5500 Reset	GP6
Relay	GP7
UART TX	GP0
UART RX	GP1

IR Pico

Function	GPIO
IR LED	GP15
UART TX	GP0
UART RX	GP1
Onboard LED	GP25

Network Configuration

Default settings (edit pico_visca/config.py):

• IP: 192.168.5.177
• Subnet: 255.255.255.0
• Gateway: 192.168.5.1
• VISCA Port: 52381 (UDP)

Installation

1. Install MicroPython

Flash MicroPython with WIZNET5K support to both Picos.

2. Upload VISCA Pico Code

Copy to the first Pico:

pico_visca/main.py      → main.py
pico_visca/config.py    → config.py
pico_visca/visca_parser.py → visca_parser.py
pico_visca/protocol.py  → protocol.py

3. Upload IR Pico Code

Copy to the second Pico:

pico_ir/main.py         → main.py
pico_ir/protocol.py     → protocol.py

4. Connect Hardware

1. Wire W5500 to VISCA Pico (SPI)
2. Wire IR LED circuit to IR Pico GP15
3. Connect UART between Picos (TX↔RX cross-connection)
4. Connect relay to VISCA Pico GP7 (optional)

5. Power On

Both Picos start automatically. The IR Pico sends OK after 8 seconds to enable camera IR mode.

PTZ Controller (PC Software)

Run the included GUI controller:

python3 ptz_controller.py

Features:

• Editable Bridge IP address
• Pan/Tilt/Zoom buttons
• Keyboard shortcuts (arrows, +/-, Space)
• Automatic connectivity monitoring

Supported VISCA Commands

Pan-Tilt

Direction	VISCA Command
Up	81 01 06 01 VV WW 03 01 FF
Down	81 01 06 01 VV WW 03 02 FF
Left	81 01 06 01 VV WW 01 03 FF
Right	81 01 06 01 VV WW 02 03 FF
Stop	81 01 06 01 VV WW 03 03 FF

Diagonal movements are supported by alternating pan/tilt IR commands.

Zoom

Action	VISCA Command
Zoom In	81 01 04 07 2X FF
Zoom Out	81 01 04 07 3X FF
Stop	81 01 04 07 00 FF

LifeSize IR Protocol

• Carrier: 38kHz
• Header: 2550µs mark, 2500µs space
• Bit 0: 1200µs mark, 1050µs space
• Bit 1: 1200µs mark, 2825µs space
• Frame: Device (0x98) + Command (8-bit)
• Gap: 57.325ms between frames (critical!)

IR Command Codes

Button	Code
UP	0x15
DOWN	0x1A
LEFT	0x25
RIGHT	0x2A
OK	0x1C
ZOOM IN	0x34
ZOOM OUT	0x3B

IR LED Circuit

GP15 ──[1kΩ]──┬── Base (B)
              │
            2N2222
              │
           Emitter (E) ── GND
              │
           Collector (C)
              │
            [100Ω]
              │
           IR LED (+)
              │
           IR LED (-) ── 3.3V

Troubleshooting

Camera doesn't respond to IR:

• Camera may have timed out of IR mode. Restart IR Pico or press OK button.
• Check IR LED is working (phone camera can see IR).

Jerky/stuttering movement:

• The 57.325ms gap timing may be off. Check IR_PACKET_GAP_US in protocol.py.

No network connection:

• Verify IP address matches your network subnet.
• Check W5500 wiring (SPI pins, reset pin).
• Try pinging the bridge IP.

STOP command ignored:

• Ensure IR Pico checks UART every loop iteration.

Testing

Test IR Pico Standalone

Upload pico_ir/test_ir.py for keyboard-controlled testing:

• WASD or Arrow keys: Pan/Tilt
• +/-: Zoom
• O: OK button
• Q: Quit

Debug Output

Enable debug flags in pico_visca/config.py:

DEBUG_VISCA = True   # Print VISCA commands
DEBUG_UART = True    # Print UART communication

File Structure

├── pico_visca/           # VISCA Pico (network handler)
│   ├── main.py           # Entry point, network, relay control
│   ├── config.py         # IP address, pin definitions
│   ├── visca_parser.py   # VISCA command parsing
│   └── protocol.py       # UART protocol definitions
│
├── pico_ir/              # IR Pico (timing-critical)
│   ├── main.py           # IR transmission, UART handling
│   ├── protocol.py       # UART protocol definitions
│   └── test_ir.py        # Keyboard test script
│
├── ptz_controller.py     # PC GUI controller
├── README.md             # This file
└── CLAUDE.md             # AI assistant context

License

MIT License