Meck/Serial Settings Guide.md

Meck Serial Settings Guide

Configure your T-Deck Pro's Meck firmware over USB serial — no companion app needed. Plug in a USB-C cable, open a serial terminal, and you have full access to every setting on the device.

Getting Started

What You Need

• T-Deck Pro running Meck firmware
• USB-C cable
• A serial terminal application:
  • Windows: PuTTY, TeraTerm, or the Arduino IDE Serial Monitor
  • macOS: screen, CoolTerm, or the Arduino IDE Serial Monitor
  • Linux: screen, minicom, picocom, or the Arduino IDE Serial Monitor

Connection Settings

Parameter	Value
Baud rate	115200
Data bits	8
Parity	None
Stop bits	1
Line ending	CR (carriage return) or CR+LF

Quick Start (macOS / Linux)

screen /dev/ttyACM0 115200

On macOS the port is typically /dev/cu.usbmodem*. On Linux it is usually /dev/ttyACM0 or /dev/ttyUSB0.

Quick Start (Arduino IDE)

Open Tools → Serial Monitor, set baud to 115200 and line ending to Carriage Return or Both NL & CR.

Once connected, type help and press Enter to confirm everything is working.

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Command Reference

All commands follow a simple pattern: get to read, set to write.

Viewing Settings

Command	Description
get all	Dump every setting at once
get name	Device name
get freq	Radio frequency (MHz)
get bw	Bandwidth (kHz)
get sf	Spreading factor
get cr	Coding rate
get tx	TX power (dBm)
get radio	All radio params in one line
get utc	UTC offset (hours)
get notify	Keyboard flash notification (on/off)
get largefont	Larger font mode (on/off)
get gps	GPS status and interval
get pin	BLE pairing PIN
get path.hash.mode	Path hash size (0=1-byte, 1=2-byte, 2=3-byte)
get rxdelay	Rx delay base (0=disabled)
get af	Airtime factor
get multi.acks	Redundant ACKs (0 or 1)
get int.thresh	Interference threshold (0=disabled)
get tx.fail.reset	TX fail reset threshold (0=disabled, default 3)
get rx.fail.reboot	RX stuck reboot threshold (0=disabled, default 3)
get gps.baud	GPS baud rate (0=compile-time default)
get channels	List all channels with index numbers
get presets	List all radio presets with parameters
get pubkey	Device public key (hex)
get firmware	Firmware version string
clock	Current RTC time (UTC + epoch)

4G variant only:

Command	Description
get modem	Modem enabled/disabled
get apn	Current APN
get imei	Device IMEI

Changing Settings

Device Name

set name MyNode

Names cannot contain these characters: [ ] / \ : , ? *

Radio Parameters (Individual)

Each of these applies immediately — no reboot required.

set freq 910.525
set bw 62.5
set sf 7
set cr 5
set tx 22

Valid ranges:

Parameter	Min	Max
freq	400.0	928.0
bw	7.8	500.0
sf	5	12
cr	5	8
tx	1	Board max (typically 22)

Radio Parameters (All at Once)

Set frequency, bandwidth, spreading factor, and coding rate in a single command:

set radio 910.525 62.5 7 5

Radio Presets

The easiest way to configure your radio. First, list the available presets:

get presets

This prints a numbered list like:

  Available radio presets:
     0  Australia                       915.800 MHz  BW250.0  SF10  CR5  TX22
     1  Australia (Narrow)              916.575 MHz  BW62.5   SF7   CR8  TX22
    ...
    14  USA/Canada (Recommended)        910.525 MHz  BW62.5   SF7   CR5  TX22
    15  Vietnam                         920.250 MHz  BW250.0  SF11  CR5  TX22

Apply a preset by name or number:

set preset USA/Canada (Recommended)
set preset 14

Preset names are case-insensitive, so set preset australia works too. The preset applies all five radio parameters (freq, bw, sf, cr, tx) and takes effect immediately.

UTC Offset

set utc 10

Range: -12 to +14.

Keyboard Notification Flash

Toggle whether the keyboard backlight flashes when a new message arrives:

set notify on
set notify off

Larger Font Mode

Toggle larger text on channel messages, contacts, DM inbox, and repeater admin screens:

set largefont on
set largefont off

BLE PIN

set pin 123456

Path Hash Mode

Controls the byte size of each repeater's identity stamp in forwarded flood packets. Larger hashes reduce collisions at the cost of fewer maximum hops.

set path.hash.mode 1

Mode	Bytes/hop	Max hops	Notes
0	1	64	Legacy — prone to hash collisions in larger networks
1	2	32	Recommended — effectively eliminates collisions
2	3	21	Maximum precision, rarely needed

Nodes with different modes can coexist — the mode only affects packets your node originates. The hash size is encoded in each packet's header, so receiving nodes adapt automatically.

Mesh Tuning

These settings control how the device participates in the mesh network. They take effect immediately — no reboot required (except gps.baud).

Rx Delay (rxdelay)

Delays processing of flood packets based on signal quality. Stronger signals are processed first; weaker copies wait longer and are typically discarded as duplicates. Direct messages are always processed immediately.

set rxdelay 3

Range: 0–20 (0 = disabled, default). Higher values create larger timing differences between strong and weak signals. Values below 1.0 have no practical effect. See the MeshSydney wiki for detailed tuning profiles.

Airtime Factor (af)

Adjusts how long certain internal timing windows remain open. Does not change the LoRa radio parameters (SF, BW, CR) — those remain as configured.

set af 1.0

Range: 0–9 (default: 1.0). Keep this value consistent across nodes in your mesh for best coherence.

Multiple Acknowledgments (multi.acks)

Sends redundant ACK packets for direct messages. When enabled, two ACKs are sent (a multi-ack first, then the standard ACK), improving delivery confirmation reliability.

set multi.acks 1

Values: 0 (single ACK) or 1 (redundant ACKs, default).

Interference Threshold (int.thresh)

Enables channel activity scanning before transmitting. Not recommended unless your device is in a high RF interference environment — specifically where the noise floor is low but shows significant fluctuations indicating interference. Enabling this adds approximately 4 seconds of receive delay per packet.

set int.thresh 14
set int.thresh 0

Values: 0 (disabled, default) or 14+ (14 is the typical setting). Values between 1–13 are not functional and will be rejected.

TX Fail Reset Threshold (tx.fail.reset)

Automatically resets the radio hardware after this many consecutive failed transmission attempts. This recovers from "zombie radio" states where the SX1262 stops responding to send commands.

set tx.fail.reset 3
set tx.fail.reset 0

Values: 0 (disabled) or 1–10 (default: 3). After the threshold is reached, the radio is reset and the failed packet is re-queued.

RX Stuck Reboot Threshold (rx.fail.reboot)

Automatically reboots the device after this many consecutive RX-stuck recovery failures. An RX-stuck event occurs when the radio is not in receive mode for 8 seconds despite automatic recovery attempts.

set rx.fail.reboot 3
set rx.fail.reboot 0

Values: 0 (disabled) or 1–10 (default: 3). A full device reboot is a last resort — this should only trigger in rare cases of persistent radio hardware malfunction.

GPS Baud Rate (gps.baud)

Override the GPS serial baud rate. The default (0) uses the compile-time value of 38400. Requires a reboot to take effect — the GPS serial port is only configured at startup.

set gps.baud 9600
set gps.baud 0

Valid rates: 0 (default), 4800, 9600, 19200, 38400, 57600, 115200.

Channel Management

List Channels

get channels

Output:

  [0] #public
  [1] #meck-test
  [2] #local-group

Add a Hashtag Channel

set channel.add meck-test

The # prefix is added automatically if you omit it. The channel's encryption key is derived from the name (SHA-256), matching the same method used by the on-device Settings screen and companion apps.

Delete a Channel

set channel.del 2

Channels are referenced by their index number (shown in get channels). Channel 0 (public) cannot be deleted. Remaining channels are automatically compacted after deletion.

4G Modem (4G Variant Only)

Enable / Disable Modem

set modem on
set modem off

Set APN

set apn telstra.internet

To clear a custom APN and revert to auto-detection on next boot:

set apn

Clock Sync

Set the device's real-time clock from a Unix timestamp. This is especially important for the T5S3 E-Paper Pro which has no GPS to auto-set the clock. These are standalone commands (not get/set prefixed) — matching the same clock sync command used on MeshCore repeaters.

View Current Time

clock

Output:

  > 2026-03-13 04:22:15 UTC (epoch: 1773554535)

If the clock has never been set:

  > not set (epoch: 0)

Sync Clock from Serial

clock sync 1773554535

The value must be a Unix epoch timestamp in the 2024–2036 range.

Quick one-liner from your terminal (macOS / Linux / WSL):

echo "clock sync $(date +%s)" > /dev/ttyACM0

Or paste directly into the Arduino IDE Serial Monitor:

clock sync 1773554535

Tip: On macOS/Linux, run date +%s to get the current epoch. On Windows PowerShell: [int](Get-Date -UFormat %s).

Boot-Time Auto-Sync (T5S3)

When the T5S3 boots with no valid RTC time and detects a USB serial host is connected, it sends a MECK_CLOCK_REQ handshake over serial. If you're using PlatformIO's serial monitor (pio device monitor), the built-in clock_sync monitor filter responds automatically with the host computer's current time — no user action required. The sync appears transparently in the boot log:

MECK_CLOCK_REQ
  (Waiting 3s for clock sync from host...)
  > Clock synced to 1773554535

If no USB host is connected (e.g. running on battery), the sync window is skipped entirely with no boot delay.

Manual fallback: If you're using a serial terminal that doesn't have the filter (e.g. screen, PuTTY), you can paste a clock sync command during the 3-second window, or any time after boot:

clock sync $(date +%s)

System Commands

Command	Description
reboot	Restart the device
rebuild	Erase filesystem, re-save identity + prefs + contacts + channels
erase	Format the filesystem (caution: loses everything)
ls UserData/	List files on internal filesystem
ls ExtraFS/	List files on secondary filesystem
cat UserData/<path>	Dump file contents as hex
rm UserData/<path>	Delete a file
help	Show command summary

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Common Workflows

First-Time Setup

Plug in your new T-Deck Pro and run through these commands to get on the air:

set name YourCallsign
set preset Australia
set utc 10
set channel.add local-group
get all

Switching to a New Region

Moving from Australia to the US? One command:

set preset USA/Canada (Recommended)

Verify with:

get radio

Custom Radio Configuration

If none of the presets match your local group or you need specific parameters, set them directly. You can do it all in one command:

set radio 916.575 62.5 8 8
set tx 20

Or one parameter at a time if you're only adjusting part of your config:

set freq 916.575
set bw 62.5
set sf 8
set cr 8
set tx 20

Both approaches apply immediately. Confirm with get radio to double-check everything took:

get radio
  > freq=916.575 bw=62.5 sf=8 cr=8 tx=20

Troubleshooting Radio Settings

If you're not sure what went wrong, dump everything:

get all

Compare the radio section against what others in your area are using. If you need to match exact parameters from another node:

set radio 916.575 62.5 7 8
set tx 22

Backing Up Your Settings

Use get all to capture a snapshot of your configuration. Copy the serial output and save it — you can manually re-enter the settings after a firmware update or device reset if your SD card backup isn't available.

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Tips

• All radio changes apply live. There is no need to reboot after changing frequency, bandwidth, spreading factor, coding rate, or TX power. The radio reconfigures on the fly.
• Preset selection by number is faster. Once you've seen get presets, use the index number instead of typing the full name.
• Settings are persisted immediately. Every set command writes to flash. If power is lost, your settings are safe.
• SD card backup is automatic. If your T-Deck Pro has an SD card inserted, settings are backed up after every change. On a fresh flash, settings restore automatically from the SD card.
• The get all command is your friend. When in doubt, dump everything and check.