Meshtastic Bridge

Made by humans shield

Configuration

The bridge is configured using the config.json file on the device's file system. Some settings can be changed using remote admin from another node.

Any properties in the config.json file that are ommitted will be set to their default values. ESP32 hardware allows for the config file to be uploaded directly from the IDE using pio run --target uploadfs --environment esp32c6.

{
 "usePst1": true,
 "mPst1": 0,
 "bw1": 0.0,
 "sf1": 0,
 "cr1": 0,
 "hops1": 3,
 "clip1": 7,
 "tx1": true,
 "pwr1": 17,
 "fs1": 0,
 "bst1": true,
 "fq1": 0.0,
 "rpt1": false,
 "usePst2": true,
 "mPst2": 6,
 "bw2": 0.0,
 "sf2": 0,
 "cr2": 0,
 "hops2": 3,
 "clip2": 7,
 "tx2": true,
 "pwr2": 17,
 "fs2": 0,
 "bst2": true,
 "fq2": 0.0,
 "admK": "",
 "chN1": "",
 "chK1": "",
 "chN2": "",
 "chK2": "",
 "bstHop": 0,
 "id1": null,
 "id2": null,
 "ln1": "",
 "sn1": "",
 "ln2": "",
 "sn2": "",
 "rpt2": false,
 "lat": 0,
 "lon": 0,
 "alt": 0,
 "adcF": 1.0,
 "nodeInfoInt": 3600,
 "nodeInfoEn": true,
 "tmyInt": 3600,
 "tmyEn": true,
 "pTmyInt": 3600,
 "pTmyEn": true,
 "posInt": 3600,
 "posEn": true,
 "ngbIInt": 3600,
 "ngbIEn": true,
 "rlThr": 20,
 "rlCap": 10,
 "rlRef": 360,
 "lowBatCut": 3400,
 "lowBatRes": 3600,
 "dsSec": 1800,
 "lsEn": true,
 "lsWake": 1000,
 "lsSec": 30
}

E22 900M30S radio module (on ESP32 bridge)

• Tested TX levels for E22 900M30S radio modules
• Some reverse engineering of the E22 900M30S radio modules

Remote admin

The bridge can be remotely configured using the meshtatic app from another node, either via PKI or legacy admin.

Additionally all above settings can be queried and updated using text messages on the legace admin channel or PKI encrypted direct messages.

When using the legacy admin channel the target needs to be identified by nodeId or shortName, e.g. sending one of the following messages:

• {"to":1234567890,"get":"tx1"}
• {"to":B0SF,"get":"tx1"}

When using PKI encrypted DMs there is no need for the to property:

• {"get":"tx1"}

To query a setting use {"get":"<property name>"} and the bridge replies with the value: {"tx1":true}.

To change a setting use {"<property name>":<new value>} with value being the correct json type, e.g.

• true/false (boolean) {"tx1":true}
• "text" (strings) {"sn1":"B0SF"}
• 1.234/17 (numbers) {"pwr1":22}

The bridge will reply depending on success of the change:

• value was successfully changed OK, tx1=>true
• value was already as requested OK, tx1=>: unchanged
• value was an invalid type OK, tx1=>: invalid type (e.g. when using "true" instead of true)
• if the property name was invalid: Invalid config name

Hardware revisions

ESP32-C6 (initial version)

Power consumption:

nRF52840

PCB render

This version uses an nRF52840 MCU and 2 SX1262 modules.

Power sources:

• USB-C, 5V
• 1S LiPo, max 5V. 3.3V undervoltage protection
• Solar charge controller (BQ24074RGT) (4.35-10.2V @ max 1.5A)
• optional thermistor to drive LiPo charge controller
• internal DC-DC regulator (TLV62569PDRLR), max 5.5V@2V

Note: when no battery is connected the charge controller will connect any input directly to the internal DC-DC controller, and care needs to be taken to limit the solar input to 5.5V max. NOTE: v0.1 silk screen has S and B swapped on the JST2.0 battery/solar connectors.

SX1262 configuration:

• DC-DC voltage regulator
• DIO3 driven TCXO (set to 1.8V)
• DIO2 for Rx/Tx switch

Pinout:

Initial flashing:

Use nanoDAP or similar SWD adapter and flash nRF's softdevice and the bootloader:

• pyocd flash -t nrf52840 "s140_nrf52_6.1.1_softdevice.hex" source
• pyocd flash -t nrf52840 "meshhopper_bootloader-0.9.2_s140_6.1.1.hex" source

Once the softdevice and bootloader have been flashed, the bridge can be set in debug mode by double-clicking the reset button (or holding it during power on), connecting via USB and dropping a UF2 file in the drive.

A UF2 version of the bootloader is also available and can be flashed via USB.