Standard 3-wire RS232
GB-01 uses a DB9 male connector with pin 2 RX, pin 3 TX, and pin 5 ground. The current hardware is intended for devices that communicate over TX, RX, and GND without required modem-control lines.
// GhostBridge v1.0 (GB-01) · WiFi ↔ standard 3-wire RS232
Put RS232 on WiFi.
Keep the connection local.
GhostBridge GB-01 is a compact assembled WiFi-to-RS232 TCP serial bridge for compatible standard 3-wire RS232 equipment. It transparently relays bytes between a local TCP connection and its DB9 serial interface without requiring a router, internet connection, cloud service, or proprietary application protocol.
Not sure your equipment is a fit? Check your device before ordering.
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3-wire RS232TX · RX · GND
WiFiLocal access point
TCPTransparent byte relay
No cloudNo internet required
USB-CPower input
// What it does
A transparent local RS232 bridge.
GhostBridge moves serial bytes between standard 3-wire RS232 and a local TCP connection. It does not need to understand the device's application protocol, which makes the same hardware useful across compatible automotive, embedded, industrial, test, and legacy serial applications.
Its own WiFi network
No router or internet connection is required. A phone, tablet, computer, or other compatible TCP client can connect directly to the bridge's local access point.
Transparent TCP transport
GhostBridge relays bytes in both directions between RS232 and TCP instead of interpreting ECU commands, instrument messages, or another application protocol.
No cloud dependency
Serial traffic stays on the direct local connection. GhostBridge does not require a cloud relay, account, subscription, or internet service to move data.
Assembled hardware
The bridge arrives assembled in an enclosure with accessible DB9 RS232 and USB-C power connections for practical bench, garage, and field use.
Verified automotive use
GhostTune with the published MicroSquirt / MS2/Extra 3.4.4 configuration is one verified production application of the broader serial-bridge hardware.
// Connection path
One local link from serial hardware to a modern client.
RS232 deviceCompatible TX / RX / GND equipment
GhostBridgeDB9 RS232 ↔ WiFi TCP
Local WiFiDirect access point connection
ClientPC · phone · tablet · embedded app
// Where it can fit
Built around the interface, not one application.
A compatible device does not need to be an ECU. The important questions are whether it uses true RS232, the required signals are available on GB-01, its serial settings can be matched, and the host software can communicate through TCP or a suitable TCP-to-COM layer.
Industrial & automation
Controllers, meters, programming/configuration ports, and other equipment using compatible standard 3-wire RS232 interfaces.
Test & measurement
Benchtop instruments, data loggers, laboratory equipment, and measurement devices that communicate over compatible RS232.
Embedded & custom hardware
Controllers, development systems, and purpose-built products that expose a compatible RS232 serial interface.
Automotive & diagnostics
ECUs, diagnostic hardware, and vehicle controllers that use a compatible 3-wire RS232 connection. GhostTune is the currently verified Crux Resolve automotive application.
Legacy equipment
Older hardware that still works well but expects a physical serial connection to a computer or controller.
Custom / OEM applications
For repeat deployments, application-specific defaults, custom firmware behavior, or integration review, see Custom & OEM Serial Solutions.
// Technical specifications
Know the interface before you connect it.
Serial side
- Electrical interface: RS232 through a MAX3232 transceiver.
- Connector: DB9 male.
- Pin 2: RXD into GhostBridge.
- Pin 3: TXD out of GhostBridge.
- Pin 5: signal ground.
- Current hardware flow control: none. RTS/CTS, DTR/DSR, DCD, RI, and other modem-control lines are not connected.
Network & power side
- WiFi mode: local access point.
- Default address:
192.168.4.1. - Default TCP port:
35000. - Transport behavior: transparent bidirectional serial byte relay over TCP.
- Internet / cloud: not required.
- Power: USB-C input.
Serial settings still matter: baud rate, data bits, parity, stop bits, cabling, timing expectations, and host-software behavior must match the connected device. Firmware capabilities determine which serial configurations are available on a given GhostBridge release.
// Basic connection
Three pieces make the link.
Connect RS232 and power
Connect a compatible standard 3-wire RS232 device to the DB9 interface and power GhostBridge through USB-C. Depending on the DTE/DCE arrangement, your installation may require a straight-through or null-modem/crossover cable.
Join the bridge network
Select the network named GhostBridge-XXXXX. The password is 1234 followed by the last four characters of that WiFi name. Example: GhostBridge-ABCDE uses password 1234BCDE.
Connect the client
Use compatible software to open a TCP connection to 192.168.4.1:35000. Legacy desktop applications that require a COM port may need a suitable TCP-to-virtual-COM solution.
// Verified automotive application
Using GhostBridge with GhostTune?
For the published verified MicroSquirt / MS2/Extra 3.4.4 workflow, GhostTune provides the iPhone and iPad interface for live ECU data, VE/ignition/AFR table editing, diagnostics, backups, and guarded ECU changes over the local GhostBridge connection.
Using other serial equipment? Start with the RS232 over WiFi guide and the compatibility checklist below. If you want Crux Resolve to review an unlisted device before you order, use the compatibility request form.
// Compatibility checklist
Will GhostBridge work with my device?
A strong candidate uses
- True RS232 electrical signaling rather than TTL serial, RS485, CAN, or another interface.
- Three-wire communication using TX, RX, and GND.
- A compatible DTE/DCE pinout or cabling arrangement.
- Serial settings that the installed GhostBridge firmware can match.
- Host software that can communicate through TCP or through a compatible TCP-to-virtual-COM layer.
- No required RTS/CTS, DTR/DSR, DCD, RI, or other modem-control signals.
Current GB-01 boundaries
- DB9 male: pin 2 RX, pin 3 TX, pin 5 GND.
- Current hardware does not route RTS/CTS or other modem-control lines.
- A DB9 connector alone does not prove the device uses compatible RS232 signaling.
- Some DTE-to-DTE or DCE-to-DCE combinations require a null-modem/crossover cable.
- Unusual timing, BREAK behavior, nonstandard UART modes, or application-specific control-line behavior may require additional validation.
- For repeat deployments or application-specific firmware behavior, see Custom & OEM Serial Solutions.
Do not connect by connector shape alone: confirm the device documentation identifies a compatible RS232 interface and pinout before connecting GhostBridge.
Verified automotive use: GhostTune with MicroSquirt hardware running MS2/Extra 3.4.4 remains the currently published verified ECU configuration. That verified application does not limit the GB-01 hardware to ECU use.
// Pre-order compatibility review
Tell us what you want to connect.
Before you order, send the device and software details you know. Crux Resolve can compare them with the current GB-01 interface and point out obvious fit issues, missing information, or questions that should be resolved first.
What helps most
A manufacturer and model number are enough to start. If available, also include a public manual link or pinout, baud/data/parity/stop settings, flow-control requirements, and the software you plan to use.
A compatibility review is a pre-order fit check, not a guarantee for undocumented timing, proprietary protocol behavior, or software that has not been tested with the actual equipment.
// GhostBridge FAQ
Common serial-bridge questions.
Can GhostBridge be used without GhostTune?
Yes. GhostBridge is a transparent local TCP-to-RS232 bridge and is not software-locked to GhostTune. A non-GhostTune device still has to meet the GB-01 electrical, signal, serial, cabling, and host-software requirements.
What RS232 signals does GB-01 provide?
The current GB-01 provides standard 3-wire RS232: DB9 pin 2 RX, pin 3 TX, and pin 5 ground. RTS/CTS, DTR/DSR, DCD, RI, and other modem-control lines are not connected.
Does GhostBridge require internet access or a router?
No. GhostBridge creates its own local WiFi access point. A compatible TCP client connects directly to the bridge at 192.168.4.1:35000.
Can it carry binary serial data?
Yes. GhostBridge relays serial bytes transparently in both directions. It does not need to understand the device's application protocol in order to transport the data.
Will every DB9 device work?
No. DB9 is only a connector. The connected device must use compatible RS232 signaling, pinout, serial settings, timing behavior, and host software.
Does GB-01 support RTS/CTS?
No. The current production GB-01 does not route the MAX3232's unused second channel to the DB9 connector, so hardware RTS/CTS flow control is not available.
Do I need a null-modem cable?
It depends on the other device's DTE/DCE arrangement. Some equipment connects straight-through; other combinations require TX/RX crossover through a null-modem cable or adapter.
What is verified today?
The currently published verified automotive configuration is GhostTune with MicroSquirt hardware running MS2/Extra 3.4.4. Other devices can be evaluated against the same published GB-01 interface requirements.
// Order
GhostBridge is available now.
Need it for non-automotive serial equipment? Review the compatibility checklist above or send Crux Resolve the device model before ordering.
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