@ -456,7 +456,7 @@ This document provides an overview of CLI commands that can be sent to MeshCore
**Note:** the 'path.hash.mode' sets the low-level ID/hash encoding size used when the repeater adverts. This setting has no impact on what packet ID/hash size this repeater forwards, all sizes should be forwarded on firmware >= 1.14. This feature was added in firmware 1.14
**Temporary Note:** adverts with ID/hash sizes of 2 or 3 bytes may have limited flood propogation in your network while this feature is new as v1.13.0 firmware and older will drop packets with multibyte path ID/hashes as only 1-byte hashes are suppored. Consider your install base of firmware >=1.14 has reached a criticality for effective network flooding before implementing higher ID/hash sizes.
**Temporary Note:** adverts with ID/hash sizes of 2 or 3 bytes may have limited flood propagation in your network while this feature is new as v1.13.0 firmware and older will drop packets with multibyte path ID/hashes as only 1-byte hashes are supported. Consider your install base of firmware >=1.14 has reached a criticality for effective network flooding before implementing higher ID/hash sizes.
---
@ -490,6 +490,8 @@ This document provides an overview of CLI commands that can be sent to MeshCore
**Default:** `0.5`
**Note:** When multiple nearby repeaters all hear the same flood packet, each waits a random amount of time before retransmitting to avoid simultaneous collisions. This factor scales the size of that random window. Higher values reduce collision risk at the cost of added latency. `0` disables the window entirely.
---
#### View or change the retransmit delay factor for direct traffic
@ -502,6 +504,8 @@ This document provides an overview of CLI commands that can be sent to MeshCore
**Default:** `0.2`
**Note:** Same collision-avoidance random window as `txdelay`, but applied to direct (non-flood, routed) traffic. The default is lower because direct packets are addressed to a specific next hop, so far fewer nodes compete to retransmit them.
---
#### [Experimental] View or change the processing delay for received traffic
@ -514,6 +518,8 @@ This document provides an overview of CLI commands that can be sent to MeshCore
**Default:** `0.0`
**Note:** When enabled, repeaters that received a flood packet with a weak signal are held in a delay queue before processing, while those that received it with a strong signal process it immediately. This gives strong-signal paths forwarding priority. By the time weak-signal nodes process their copy, the packet may have already propagated and will be suppressed as a duplicate, reducing redundant retransmissions.
**Purpose**: Send binary datagram data to a channel.
**Purpose**: Send a binary datagram to a channel. Unlike channel text messages, datagramscarry no built-in sender identity and no timestamp— applications needing either must encode them inside the binary payload.
**Command Format**:
```
Byte 0: 0x3E
Bytes 1-2: Data Type (`data_type`, 16-bit little-endian)
- `0x0000`(`DATA_TYPE_RESERVED`) is invalid and rejected with `PACKET_ERROR`.
- `0xFFFF` (`DATA_TYPE_DEV`) is the developer namespace for experimenting and developing apps.
- Other non-zero values can be used as assigned application/community namespaces.
**Note**: Applications that need a timestamp should encode it inside the binary payload.
- Values `0x0001`–`0xFFFE` are available for registered application/community namespaces. See the [Registered data_type values](#registered-data_type-values) table below.
**Limits**:
- Maximum payload length is `163` bytes.
- Larger payloads are rejected with `PACKET_ERROR`.
- Maximum payload length is `MAX_CHANNEL_DATA_LENGTH = MAX_FRAME_SIZE - 9 = 163` bytes.
- Larger payloads are rejected with `PACKET_ERROR` (`ERR_CODE_ILLEGAL_ARG`).
**Response**: `PACKET_OK` (0x00) on success, or `PACKET_ERROR` (0x01) with one of:
- `ERR_CODE_ILLEGAL_ARG` (6) — invalid `path_len`, reserved `data_type` (`0x0000`), or payload larger than `MAX_CHANNEL_DATA_LENGTH`
- `ERR_CODE_TABLE_FULL` (3) — outbound send queue is full; retry later
**Inbound datagrams** are delivered to the host via `RESP_CODE_CHANNEL_DATA_RECV` (0x1B); see [Receive Channel Data Datagram](#receive-channel-data-datagram).
#### Registered `data_type` values
`data_type` is an **application identifier**, not a payload-format identifier. Each registered value identifies an application that owns its own internal payload schemas. The firmware does not inspect payload contents — `data_type` is transported opaquely.
To register a new application, submit a PR adding a row to the table in [docs/number_allocations.md](number_allocations.md). Internal sub-formats within an allocated application ID are owned by that application and are not tracked in MeshCore firmware or this document.
---
### 6. Get Message
### Receive Channel Data Datagram
Inbound group datagrams (radio-level `PAYLOAD_TYPE_GRP_DATA`, 0x06) are forwarded to the host as `RESP_CODE_CHANNEL_DATA_RECV` notifications.
Byte 1: SNR (signed int8, scaled ×4 — divide by 4.0 to recover dB)
Bytes 2-3: Reserved (clients MUST ignore)
Byte 4: Channel Index (0-7)
Byte 5: Path Length (actual path length when flooded, otherwise 0xFF for direct)
Bytes 6-7: Data Type (uint16 little-endian)
Byte 8: Data Length
Bytes 9 .. 8+data_len: Payload
```
**Path bytes are not forwarded**: Only `path_len` is reported in the receive frame — the path itself is not copied to the host. There are no path bytes between byte 5 and the data_type field at bytes 6–7, regardless of `path_len`.
**Path Length semantics differ between send and receive**:
| Send | Flood the network | Direct route; the encoded path follows (low 6 bits = hash count, top 2 bits + 1 = hash size; on-wire byte count = `hash_count × hash_size`) |
| Receive | Packet arrived via direct route | Packet was flooded; this is the encoded `pkt->path_len` field as observed (no path bytes follow) |
In other words, the meaning of `0xFF` is inverted between the two directions, and on receive the field carries metadata only — never a routable path. `path_len` is an encoded byte (see `Packet::isValidPathLen` / `Packet::writePath` in `src/Packet.cpp`), not a raw byte count.
**Note**: The device may also emit `PACKET_MESSAGES_WAITING` (0x83) to notify the host that datagrams are queued; poll with `CMD_SYNC_NEXT_MESSAGE` (0x0A) to retrieve them.
**Parsing Pseudocode**:
```python
def parse_channel_data_recv(data):
if len(data) <9:
return None
snr_byte = data[1]
snr = (snr_byte if snr_byte <128elsesnr_byte-256)/4.0
channel_idx = data[4]
path_len = data[5]
data_type = int.from_bytes(data[6:8], 'little')
data_len = data[8]
if 9 + data_len > len(data):
return None
payload = data[9:9 + data_len]
return {
'snr': snr,
'channel_idx': channel_idx,
'path_len': path_len,
'data_type': data_type,
'payload': bytes(payload),
}
```
---
### 7. Get Message
**Purpose**: Request the next queued message from the device.
@ -325,13 +403,14 @@ Byte 0: 0x0A
**Response**:
- `PACKET_CHANNEL_MSG_RECV` (0x08) or `PACKET_CHANNEL_MSG_RECV_V3` (0x11) for channel messages
- `PACKET_CONTACT_MSG_RECV` (0x07) or `PACKET_CONTACT_MSG_RECV_V3` (0x10) for contact messages
- `PACKET_CHANNEL_DATA_RECV` (0x1B) for channel data datagrams
- `PACKET_NO_MORE_MSGS` (0x0A) if no messages available
**Note**: Poll this command periodically to retrieve queued messages. The device may also send `PACKET_MESSAGES_WAITING` (0x83) as a notification when messages are available.
---
### 7. Get Battery and Storage
### 8. Get Battery and Storage
**Purpose**: Query device battery voltage and storage usage.
@ -527,6 +606,15 @@ Use the `SEND_CHANNEL_MESSAGE` command (see [Commands](#commands)).
## Response Parsing
### Terminology
This document uses a spec-level naming convention (`PACKET_*`) for bytes the firmware sends back to the host. In the firmware source these same values are split across two `#define` families by purpose:
- `RESP_CODE_*` — direct replies to a command (e.g. `RESP_CODE_CHANNEL_DATA_RECV` = `PACKET_CHANNEL_DATA_RECV` = 0x1B).
- `PUSH_CODE_*` — asynchronous notifications not tied to a specific command (e.g. `PUSH_CODE_MSG_WAITING` = `PACKET_MESSAGES_WAITING` = 0x83).
Byte values are authoritative; names are aliases. When reading firmware source, `RESP_CODE_X` / `PUSH_CODE_X` correspond to this doc's `PACKET_X` of the same numeric value.
### Packet Types
| Value | Name | Description |
@ -547,6 +635,7 @@ Use the `SEND_CHANNEL_MESSAGE` command (see [Commands](#commands)).
**PACKET_ERROR** (0x01) may include an error code in byte 1:
`PACKET_ERROR` (0x01) carries a single-byte error code in byte 1. Values match the `ERR_CODE_*` constants defined in `examples/companion_radio/MyMesh.cpp`:
@ -23,8 +23,8 @@ A list of frequently-asked questions and answers for MeshCore
- [3.3. Q: What is the password to administer a repeater or a room server?](#33-q-what-is-the-password-to-administer-a-repeater-or-a-room-server)
- [3.4. Q: What is the password to join a room server?](#34-q-what-is-the-password-to-join-a-room-server)
- [3.5. Q: Can I retrieve a repeater's private key or set a repeater's private key?](#35-q-can-i-retrieve-a-repeaters-private-key-or-set-a-repeaters-private-key)
- [3.6. Q: The first byte of my repeater's public key collides with an exisitng repeater on the mesh. How do I get a new private key with a matching public key that has its first byte of my choosing?](#36-q-the-first-byte-of-my-repeaters-public-key-collides-with-an-exisitng-repeater-on-the-mesh--how-do-i-get-a-new-private-key-with-a-matching-public-key-that-has-its-first-byte-of-my-choosing)
- [3.7. Q: My repeater maybe suffering from deafness due to high power interference near my mesh's frequency, it is not hearing other in-range MeshCore radios. What can I do?](#37-q-my-repeater-maybe-suffering-from-deafness-due-to-high-power-interference-near-my-meshs-frequency-it-is-not-hearing-other-in-range-meshcore-radios--what-can-i-do)
- [3.6. Q: The first byte of my repeater's public key collides with an existing repeater on the mesh. How do I get a new private key with a matching public key that has its first byte of my choosing?](#36-q-the-first-byte-of-my-repeaters-public-key-collides-with-an-existing-repeater-on-the-mesh--how-do-i-get-a-new-private-key-with-a-matching-public-key-that-has-its-first-byte-of-my-choosing)
- [3.7. Q: My repeater maybe suffering from deafness due to high power interference near my mesh's frequency, it is not hearing other in-range MeshCore radios. What can I do?](#37-q-my-repeater-may-be-suffering-from-deafness-due-to-high-power-interference-near-my-meshs-frequency-it-is-not-hearing-other-in-range-meshcore-radios--what-can-i-do)
- [3.8. Q: How do I make my repeater an observer on the mesh?](#38-q-how-do-i-make-my-repeater-an-observer-on-the-mesh)
- [3.9. Q: What is multi-byte support? What do 1-byte, 2-byte, 3-byte adverts and messages mean?](#39-q-what-is-multi-byte-support--what-do-1-byte-2-byte-3-byte-adverts-and-messages-mean)
- [3.9.1. Q: **What path hash sizes will my repeater forward?**](#391-q-what-path-hash-sizes-will-my-repeater-forward)
@ -39,7 +39,7 @@ A list of frequently-asked questions and answers for MeshCore
- [4.3. Q: Why is my T-Deck Plus not getting any satellite lock?](#43-q-why-is-my-t-deck-plus-not-getting-any-satellite-lock)
- [4.4. Q: Why is my OG (non-Plus) T-Deck not getting any satellite lock?](#44-q-why-is-my-og-non-plus-t-deck-not-getting-any-satellite-lock)
- [4.5. Q: What size of SD card does the T-Deck support?](#45-q-what-size-of-sd-card-does-the-t-deck-support)
- [4.6. Q: what is the public key for the default public channel?](#46-q-what-is-the-public-key-for-the-default-public-channel)
- [4.6. Q: What is the public key for the default public channel?](#46-q-what-is-the-public-key-for-the-default-public-channel)
- [4.7. Q: How do I get maps on T-Deck?](#47-q-how-do-i-get-maps-on-t-deck)
- [4.8. Q: Where do the map tiles go?](#48-q-where-do-the-map-tiles-go)
- [4.9. Q: How to unlock deeper map zoom and server management features on T-Deck?](#49-q-how-to-unlock-deeper-map-zoom-and-server-management-features-on-t-deck)
@ -52,9 +52,9 @@ A list of frequently-asked questions and answers for MeshCore
- [5.1. Q: What are BW, SF, and CR?](#51-q-what-are-bw-sf-and-cr)
- [5.2. Q: Do MeshCore clients repeat?](#52-q-do-meshcore-clients-repeat)
- [5.3. Q: What happens when a node learns a route via a mobile repeater, and that repeater is gone?](#53-q-what-happens-when-a-node-learns-a-route-via-a-mobile-repeater-and-that-repeater-is-gone)
- [5.4. Q: How does a node discovery a path to its destination and then use it to send messages in the future, instead of flooding every message it sends like Meshtastic?](#54-q-how-does-a-node-discovery-a-path-to-its-destination-and-then-use-it-to-send-messages-in-the-future-instead-of-flooding-every-message-it-sends-like-meshtastic)
- [5.4. Q: How does a node discover a path to its destination and then use it to send messages in the future, instead of flooding every message it sends like Meshtastic?](#54-q-how-does-a-node-discover-a-path-to-its-destination-and-then-use-it-to-send-messages-in-the-future-instead-of-flooding-every-message-it-sends-like-meshtastic)
- [5.5. Q: Do public channels always flood? Do private channels always flood?](#55-q-do-public-channels-always-flood-do-private-channels-always-flood)
- [5.6. Q: what is the public key for the default public channel?](#56-q-what-is-the-public-key-for-the-default-public-channel)
- [5.6. Q: What is the public key for the default public channel?](#56-q-what-is-the-public-key-for-the-default-public-channel)
- [5.7. Q: Is MeshCore open source?](#57-q-is-meshcore-open-source)
- [5.8. Q: How can I support MeshCore?](#58-q-how-can-i-support-meshcore)
- [5.9. Q: How do I build MeshCore firmware from source?](#59-q-how-do-i-build-meshcore-firmware-from-source)
@ -62,7 +62,7 @@ A list of frequently-asked questions and answers for MeshCore
- [5.11. Q: Does MeshCore support ATAK](#511-q-does-meshcore-support-atak)
- [5.12. Q: How do I add a node to the MeshCore Map](#512-q-how-do-i-add-a-node-to-the-meshcore-map)
- [5.13. Q: Can I use a Raspberry Pi to update a MeshCore radio?](#513-q-can-i-use-a-raspberry-pi-to-update-a-meshcore-radio)
- [5.14. Q: Are there are projects built around MeshCore?](#514-q-are-there-are-projects-built-around-meshcore)
- [5.14. Q: Are there projects built around MeshCore?](#514-q-are-there-projects-built-around-meshcore)
- [5.15. Q: Are there client applications for Windows or Mac?](#515-q-are-there-client-applications-for-windows-or-mac)
- [5.16. Q: Are there any resources that compare MeshCore to other LoRa systems?](#516-q-are-there-any-resources-that-compare-meshcore-to-other-lora-systems)
- [6. Troubleshooting](#6-troubleshooting)
@ -187,7 +187,7 @@ The T-Deck firmware is free to download and most features are available without
### 2.3. Q: What frequencies are supported by MeshCore?
**A:** It supports the 868MHz range in the UK/EU and the 915MHz range in New Zealand, Australia, and the USA. Countries and regions in these two frequency ranges are also supported.
Use the smartphone client or the repeater setup feature on there web flasher to set your radios' RF settings by choosing the preset for your regions.
Use the smartphone client or the repeater setup feature on the web flasher to set your radios' RF settings by choosing the preset for your regions.
Recently, as of October 2025, many regions have moved to the "narrow" setting, aka using BW62.5 and a lower SF number (instead of the original SF11). For example, USA/Canada (Recommended) preset is 910.525MHz, SF7, BW62.5, CR5.
@ -271,7 +271,7 @@ You can get the latitude and longitude from Google Maps by right-clicking the lo
Reboot the repeater after `set prv.key <hex>` command for the new private key to take effect.
### 3.6. Q: The first byte of my repeater's public key collides with an exisitng repeater on the mesh. How do I get a new private key with a matching public key that has its first byte of my choosing?
### 3.6. Q: The first byte of my repeater's public key collides with an existing repeater on the mesh. How do I get a new private key with a matching public key that has its first byte of my choosing?
**A:** You can generate a new private key and specific the first byte of its public key here: https://gessaman.com/mc-keygen/
@ -280,7 +280,7 @@ Having multiple repeaters with the same first byte ID does not negatively affect
Best practice is when you set up a new repeater, choose a public key that is not in use. If it is not possible to find a unique first byte for your repeater's public key, choose one that is unique within about 10 miles (16 km) to minimize collision with nearby repeaters.
### 3.7. Q: My repeater maybe suffering from deafness due to high power interference near my mesh's frequency, it is not hearing other in-range MeshCore radios. What can I do?
### 3.7. Q: My repeater maybe suffering from deafness due to high power interference near my mesh's frequency, it is not hearing other in-range MeshCore radios. What can I do?
**A:** This may be due to the SX1262 radio's auto gain control feature. You can use this command to periodically reset its AGC.
@ -379,7 +379,7 @@ GPS on T-Deck is always enabled. You can skip the "GPS clock sync" and the T-De
### 4.5. Q: What size of SD card does the T-Deck support?
**A:** Users have had no issues using 16GB or 32GB SD cards. Format the SD card to **FAT32**.
### 4.6. Q: what is the public key for the default public channel?
### 4.6. Q: What is the public key for the default public channel?
**A:**
T-Deck uses the same key the smartphone apps use but in base64
`izOH6cXN6mrJ5e26oRXNcg==`
@ -495,7 +495,7 @@ In MeshCore, only repeaters and room server with `set repeat on` repeat.
In the case if users are moving around frequently, and the paths are breaking, they just see the phone client retries and revert to flood to attempt to re-establish a path.
### 5.4. Q: How does a node discovery a path to its destination and then use it to send messages in the future, instead of flooding every message it sends like Meshtastic?
### 5.4. Q: How does a node discover a path to its destination and then use it to send messages in the future, instead of flooding every message it sends like Meshtastic?
Routes are stored in sender's contact list. When you send a message the first time, the message first gets to your destination by flood routing. When your destination node gets the message, it will send back a delivery report to the sender with all repeaters that the original message went through. This delivery report is flood-routed back to you the sender and is a basis for future direct path. When you send the next message, the path will get embedded into the packet and be evaluated by repeaters. If the hop and address of the repeater matches, it will retransmit the message, otherwise it will not retransmit, hence minimizing utilization.
@ -508,7 +508,7 @@ Routes are stored in sender's contact list. When you send a message the first t
### 5.14. Q: Are there are projects built around MeshCore?
### 5.14. Q: Are there projects built around MeshCore?
**A:** Yes, there are many. MeshCore's protocol is open source using the MIT license. The MIT license and the open source protocol makes it very easy for the MeshCore community to build new firmware for radios, applications on mobile devices, map tools, and analysis tools, and integration with other projects like Home Asistant.
**A:** Yes, there are many. MeshCore's protocol is open source using the MIT license. The MIT license and the open source protocol makes it very easy for the MeshCore community to build new firmware for radios, applications on mobile devices, map tools, and analysis tools, and integration with other projects like Home Assistant.
As new MeshCore community projects become available on a weekly basis, we have stopped tracking them here in this FAQ. [samuk](https://github.com/samuk) maintains a very exhausive list of MeshCore community project at https://github.com/samuk/awesome-meshcore/blob/main/README.md. samuk accepts PRs and merges them regularly.
As new MeshCore community projects become available on a weekly basis, we have stopped tracking them here in this FAQ. [samuk](https://github.com/samuk) maintains a very exhaustive list of MeshCore community project at https://github.com/samuk/awesome-meshcore/blob/main/README.md. samuk accepts PRs and merges them regularly.
### 5.15. Q: Are there client applications for Windows or Mac?
@ -708,7 +708,7 @@ You can get the epoch time on <https://www.epochconverter.com/> and use it to se
- For RAK, click the reset button **TWICE**
- For T1000-e, quickly disconnect and reconnect the magnetic side of the cable from the device **TWICE**
- For Heltec T114, click the reset button **TWICE** (the bottom button)
- For Xiao nRF52, click the reset button once. If that doesn't work, quickly double click the reset button twice. If that doesn't work, disconnection the board from your PC and reconnect again ([seeed studio wiki](https://wiki.seeedstudio.com/XIAO_BLE/#access-the-swd-pins-for-debugging-and-reflashing-bootloader))
- For Xiao nRF52, click the reset button once. If that doesn't work, quickly double click the reset button twice. If that doesn't work, disconnect the board from your PC and reconnect again ([seeed studio wiki](https://wiki.seeedstudio.com/XIAO_BLE/#access-the-swd-pins-for-debugging-and-reflashing-bootloader))
5. A new folder will appear on your computer's desktop
6. Download the `flash_erase*.uf2` file for your device on https://flasher.meshcore.io
- RAK WisBlock and Heltec T114: `Flash_erase-nRF32_softdevice_v6.uf2`
@ -818,7 +818,7 @@ Edit WIFI_SSID and WIFI_PWD in `./variants/heltec_v3/platformio.ini` and then fl
### 7.7. Q: I have a Station G2, or a Heltec V4, or an Ikoka Stick, or a radio with a EByte E22-900M30S or a E22-900M33S module, what should their transmit power be set to?
**A:**
For companion radios, you can set these radios' transmit power in the smartphone app. For repeater and room server radios, you can set their transmit power using the command line command `set tx`. You can get their current value using command line comand `get tx`
For companion radios, you can set these radios' transmit power in the smartphone app. For repeater and room server radios, you can set their transmit power using the command line command `set tx`. You can get their current value using command line command `get tx`
⚠️ **WARNING: Set these values at your own risk. Incorrect power settings can permanently damage your radio hardware.**