Serial user guide

Serial works with serial devices attached to the computer running lilygo-ui-serial. The desktop simulator also opens real host ports. Communication does not need internet access.

Before you start

• Attach the device or USB adapter and ensure its driver creates a serial node.
• Match the target's voltage levels, common ground, and transmit/receive wiring.
• The running account needs read/write access; close other serial monitors.
• Obtain the required baud rate, data bits, parity, stop bits, and flow control from the device documentation.

Connect

1. Open Serial in Launcher and tap Settings at the top.
2. Tap Scan and choose a device in Connection.
3. Set the serial parameters; defaults are 115200 / 8N1 / no flow control.
4. Tap Connect and confirm Connected.
5. Tap Back to return to the receive/send console.
6. Before changing the port or settings, return to Settings and tap Disconnect.

Settings navigation preserves the connection, receive history, and unsent draft. Hot-plug discovery and reconnection are manual: use Scan / Connect as needed.

Receive data

• ASCII / HEX: change how retained bytes are displayed.
• Time: show local timestamps for receive chunks; enabled by default.
• Auto: scroll to new data; disable it to inspect earlier content.
• Clear: remove history and reset RX/TX counters while keeping the connection and queued output.

Receive shows incoming bytes only; sending does not add a local echo. ASCII renders non-ASCII bytes as escapes instead of decoding UTF-8 text. Records follow OS read chunks, which need not match protocol messages.

Send data

1. Choose ASCII or HEX in the send pane, independently of the receive format.
2. Enter data such as ASCII AT or HEX 41 54.
3. Choose No ending, LF, CR, or CRLF to match the protocol.
4. Tap Send, inspect feedback and TX count, then wait for the device's actual response.

ASCII AT with CRLF sends 41 54 0D 0A. HEX requires complete byte pairs: 0041ff and 00 41 FF work; 0x prefixes and commas do not. ASCII does not interpret the literal text \r; use an ending or HEX for control bytes. Choose No ending if the HEX payload already contains its terminator. A TX increase means the OS accepted bytes, not that the receiver acknowledged them.

Drag the divider to resize the receive and send panes; landscape uses side-by-side panes. The input field opens a software keyboard. Hide keyboard restores space and retains the text.

Line control

Open Settings → Line control for RTS, DTR, and BREAK. An active connection and driver support are required. Manual RTS is disabled under RTS/CTS flow control. BREAK remains asserted until switched off or disconnected; it is not a timed pulse.

Data and permissions

Logs, settings, and input do not survive restarts. There is no log export or periodic send feature. Raw history is limited to 256 KiB / 512 records; formatted display is capped at 32 KiB. Disconnect drops unwritten queued output. Clear does not flush driver buffers. Common Linux nodes include /dev/ttyUSB* and /dev/ttyACM*; macOS uses /dev/cu.*. The picker intentionally hides /dev/ttyS0 and /dev/serial0 and has no custom-path field.

Troubleshooting

Symptom	What to check
No ports	Cable, driver, supported node naming, then Scan.
Permission denied	Node ownership and account access; apply system access policy and sign in again if needed.
Connected but unreadable data	Matching endpoint parameters, wiring, and ASCII/HEX display mode.
TX increases without RX	There is no local echo; verify that the other device should reply.
Line control fails	Adapter/driver support; working byte transfer does not guarantee modem-line support.

Based on the local Serial usage guide and receive/send interface implementation.

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