03 · Bluetooth

← Back to overview | Applies to: JUXI Technology KVM&HUB&TTL

What Bluetooth Is For

The device has a built-in Bluetooth module (the wireless side of the same serial channel as the 6-pin TTL port). Once a dev board or sensor is wired to the TTL port, its data is output not only on the PC serial port but also simultaneously over Bluetooth; connect a phone and you can send/receive data wirelessly.

For wiring, see 04 - TTL Serial Port. Bluetooth connection and data transfer are unaffected by computer switching (the link stays up whichever computer is selected).

How It Works (Read This First)

⚠️ Bluetooth is not a "remote control" — it is a wireless serial cable: it carries serial data between the "device on the 6-pin header" and your "phone/computer". With no external device connected, a Bluetooth connection shows no data — this is normal.

【External device】        【This product】            【You】
 Dev board/sensor ──6-pin──> serial passthrough ──┬─ wired → PC serial (USB-BLE-SERIAL CH9143)
 (produces/receives data)                          └─ wireless → phone/PC Bluetooth (BleUart App)

Example 1: View IMU attitude data wirelessly

1. Wire the IMU module's TX/RX/GND/5V to the 6-pin header (crossed, with power — see 04); the IMU starts streaming data.
2. Long-press the switch button for about 3 seconds to enter Bluetooth mode (the LED lights up).
3. Connect the phone's BleUart app to CH9143BLE2U.
4. Continuous data frames appear on the phone immediately (about 80 frames per second of attitude data in our test).
5. At the same time, opening USB-BLE-SERIAL CH9143 in a PC serial tool shows exactly the same data.

Example 2: Wireless debugging of Raspberry Pi / Jetson

1. Wire Raspberry Pi Pin8(TXD)/Pin10(RXD)/GND to the 6-pin header (crossed).
2. Boot the Raspberry Pi; the boot log is output on the serial port.
3. Connect via phone BleUart to view the boot log wirelessly.
4. Typing and sending in the app sends data out of the 6-pin TXD to the Raspberry Pi — the phone becomes a wireless serial console (log in, send commands).

Phone Connection Steps (4 Steps)

1. Long-press the switch button for about 3 seconds until the LED lights up — Bluetooth mode (advertised name: CH9143BLE2U).
2. Install the official WCH app "BleUart" on your phone (search the app store; free).
3. Open the app → tap "Connect Bluetooth" → select CH9143BLE2U from the list.
4. Connected (no password required) — start sending/receiving data.

(Illustration: tutorial asset 04 – Long-press to enter Bluetooth mode)

⚠️ Important Notes

• Do not use the phone's system Bluetooth "pairing": it will prompt for a PIN and no PIN will work — always connect BLE devices directly with the BleUart app.
• The Bluetooth module can be connected to only one host device at a time (while a phone is connected, a computer cannot connect via Bluetooth, and vice versa). The PC-side serial port (USB) is not affected and can be used simultaneously.

Troubleshooting

Problem	Solution
CH9143BLE2U not found	Long-press the button again until the LED lights; make sure you are within 10 m
PIN prompt / cannot connect	Stop system pairing and use the BleUart app instead
Cannot connect in the app	It may be occupied by another device (e.g., a computer) — disconnect the other connection first
Connected but no data	Bluetooth carries the serial data of the 6-pin header — first make sure the external device is wired to the TTL port (see 04)

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