Security+ TX

Transmits Security+ 2.0 rolling-code signals used by Chamberlain, LiftMaster, and Craftsman garage door openers and gate operators.

This is an external app and must be present on the SD card in the APPS/ folder.

🎁 Features

• Encodes and transmits Security+ 2.0 rolling-code packets (two-packet frame, Manchester OOK)
• Rolling code auto-increments after each transmission to stay in sync with the receiver
• Optional data payload field for openers that require it
• Learn mode for pairing without advancing the rolling code
• Save/load remote configurations from .SECPLUS files
• Autosave after each successful transmission

📶 Protocol

Security+ 2.0 uses OOK (On-Off Keying) with Manchester encoding at 4000 bps on 315 MHz.

Each transmission consists of two packets sent sequentially:

• Packet 1 (indicator 0b00) — encodes the first half of the rolling and fixed codes
• Packet 2 (indicator 0b01) — encodes the second half

The full transmission is repeated 3 times.

The rolling code is a 28-bit counter. The fixed code is a 40-bit device identifier. Together they form a cryptographically scrambled frame that the receiver validates. The rolling code must stay within the receiver's synchronisation window (typically ±256 counts of the last accepted value) to be accepted.

❓ User Guide

Controls

Control	Description
Open	Open a .SECPLUS file from the SECPLUS/ folder
Save	Save current data to the current file immediately
Name	Remote name (tap to edit via keyboard)
Fixed	40-bit fixed code in hex (10 digits) — permanent device identifier
Rolling	28-bit rolling code in hex (7 digits) — increments after each TX
Data	Optional 32-bit payload in hex (8 digits). Enable with the Data checkbox. Greyed out when disabled.
Learn	When checked, the rolling code does not increment after TX. Use this when pairing with a receiver or replaying a known code.
Autosave	When checked (default), the file is saved automatically after each transmission. Keeps the rolling code on disk in sync.
Progress bar	Shows transmission progress across the 3 repeat cycles.

Standard transmitter controls (frequency, LNA, VGA, AMP, TX button) are shown at the bottom.

Workflow

Transmitting a known remote:

1. Press Open and select the .SECPLUS file for the remote.
2. Verify the Fixed and Rolling codes match your remote.
3. Press TX. The rolling code increments automatically and the file is saved.

Creating a new remote entry:

1. Enter the Fixed and Rolling code values from your remote (e.g. read via SDR capture and decode).
2. Set a name and optionally enable the Data field.
3. Press Save or let Autosave handle it after the first TX.

Pairing / learning mode:

1. Enable the Learn checkbox.
2. Transmit — the rolling code stays fixed, allowing you to transmit the same code repeatedly.

📁 File Format

Remote configurations are stored as .SECPLUS files in the SECPLUS/ folder on the SD card.

The file is a single CSV line:

version;name;has_data;fixed_code;rolling_code;data

Example:

2;MyGarage;0;1A2B3C4D5E;0001F4;00000000

Field	Description
version	Protocol version — always 2 for Security+ 2.0
name	Remote name (display only)
has_data	1 if data field is used, 0 otherwise
fixed_code	40-bit fixed code in hex
rolling_code	28-bit rolling code in hex
data	32-bit optional data payload in hex

The default file SECPLUS/DEFAULT.SECPLUS is created automatically on first launch if it does not exist.