LCR - portapack-mayhem/mayhem-firmware GitHub Wiki

TEDI/LCR TX generates and transmits LCR (Langage de Commande Routier — Road Command Language) frames, a French protocol used to control dynamic road equipment: variable message signs (PMV), tunnel systems, traffic cameras, emergency phones, weather stations, and related infrastructure. It uses AFSK modulation (Bell 202-compatible) over FM.

Controls

EC — Éclairage (lighting) mode. Options: Auto (A), Jour/Day (J), Nuit/Night (N), S? (S).

RGSB — The 4-character destination address code (e.g. AI10). Press the RGSB button to enter a custom address via the keyboard. In scan mode, this is overridden by the selected address list.

AM1–AM5 — Up to 5 address message slots. Each slot has a checkbox (to include it in the frame) and a Set button to enter the 7-character payload text. Only checked slots are included in the transmitted frame.

Modem Setup — Opens the modem configuration screen where you set the baudrate and repeat count. These settings are shared with other AFSK apps and persist in memory.

Scan (checkbox) — When enabled, automatically cycles through all RGSB addresses in the selected list, transmitting the configured frame to each address in sequence.

List — Selects the preconfigured RGSB address list used in scan mode. Contains a list of known addresses for the Lille road network (36 entries).

Clear — Clears all AM slot content and unchecks all checkboxes.

START / STOP — Starts or stops transmission. A progress bar and status line show repeat and scan progress (repeat/total scan_index/total).

Message Format

The transmitted LCR frame has the following structure:

<7 sync bytes> RGSB AM=1 [AM=2 ...] EC=  

Text in each AM slot is padded to 7 characters. The checksum is an XOR of all characters from the RGSB field to the EOM byte, masked to 7 bits. The complete frame is transmitted the number of times set in Modem Setup.

Preconfigured RGSB Lists

Lille (36 addresses): AI10–AI70, AJ10–AJ70, AK10, EAA0–EAD0, EbA0–EbS0

Reims (20 addresses): AI10–AI70, AJ10–AJ70, AK10–AK70 (selected), AP10

RF Parameters

Parameter Value
Modulation AFSK / FM (Bell 202-compatible)
Mark frequency 1200 Hz
Space frequency 2200 Hz
Baud rate Configurable via Modem Setup (default: 1200 bps)
Bandwidth 1.75 MHz
Sample rate 1.536 MSps
Frequency step 10 kHz

Settings Persistence

Settings are saved to tx_lcr.ini. Baudrate and repeat count are stored in shared persistent memory via Modem Setup.