Device

ble_connect

Connects to a BLE device by address and discovers its services.

Inputs:

• address (Text) — device address from ble_scan

Output: handle (Text) — connection handle

ble_disconnect

Disconnects from a BLE device and releases the connection.

Inputs:

• handle (Text) — connection handle

Output: disconnected (Boolean) — true if disconnected

ble_list_services

Lists GATT services and characteristics on a connected BLE device.

Inputs:

• handle (Text) — connection handle from ble_connect

Output: services (Json) — array of services, each with uuid and characteristics array

ble_read

Reads data from a BLE characteristic.

Inputs:

• handle (Text) — connection handle
• service (Text) — service UUID
• characteristic (Text) — characteristic UUID

Outputs:

• data (Text) — received text data
• bytes_read (Number) — number of bytes received

ble_scan

Scans for nearby Bluetooth Low Energy devices.

Inputs:

• duration_ms (Number) — how long to scan in milliseconds

Output: devices (Json) — array of discovered devices

ble_write

Writes data to a BLE characteristic.

Inputs:

• handle (Text) — connection handle
• service (Text) — service UUID
• characteristic (Text) — characteristic UUID
• data (Text) — text data to write

Output: bytes_written (Number) — number of bytes sent

disconnect_all

Closes all serial ports and BLE connections opened by this app (does not affect system devices like headsets, mice, etc.).

Output: closed (Boolean) — true when all connections are released

gpio_read

Reads the state of a GPIO pin from a connected microcontroller via serial.

Inputs:

• handle (Text) — serial connection handle
• pin (Number) — GPIO pin number
• timeout_ms (Number) — response timeout

Outputs:

• value (Boolean) — true if HIGH
• raw (Number) — raw byte value

Notes: Sends Firmata REPORT_DIGITAL (0xD0) command.

gpio_set

Sets a GPIO pin high or low on a connected microcontroller via serial.

Inputs:

• handle (Text) — serial connection handle
• pin (Number) — GPIO pin number
• value (Boolean) — true for HIGH, false for LOW

Output: sent (Boolean) — true if command sent

Notes: Sends Firmata SET_DIGITAL_PIN (0xF5) command.

i2c_read

Reads data from an I2C device via a serial-connected microcontroller using Firmata protocol.

Inputs:

• handle (Text) — serial connection handle
• address (Number) — I2C device address (7-bit)
• register (Number) — register address
• num_bytes (Number) — number of bytes to request
• timeout_ms (Number) — response timeout

Outputs:

• data (Text) — hex-encoded response bytes
• bytes_read (Number) — number of bytes received

Notes: Sends Firmata I2C_REQUEST (0x76) read command.

i2c_write

Writes data to an I2C device via a serial-connected microcontroller using Firmata protocol.

Inputs:

• handle (Text) — serial connection handle
• address (Number) — I2C device address (7-bit)
• register (Number) — register address
• data (Text) — hex-encoded bytes

Output: sent (Boolean) — true if sent

Notes: Sends Firmata I2C_REQUEST (0x76) write command.

list_ports

Lists all available serial and USB ports on the system.

Output: ports (Json) — array of available ports with name and type info

print_label

Prints an image to a TSPL2-compatible label printer (e.g. Nelko P21) over serial.

Inputs:

• handle (Text) — serial connection handle
• image (Image) — image to print (dithered to 1-bit)
• width_px (Number) — label width in pixels
• height_px (Number) — label height in pixels
• width_mm (Number) — label width in mm
• height_mm (Number) — label height in mm
• gap_mm (Number) — gap between labels in mm
• density (Number) — print density (1-15)
• copies (Number) — number of copies
• rotate (Number) — rotate image before printing (0, 90, 180, 270)
• invert (Boolean) — invert bitmap polarity

Output: printed (Boolean) — true if sent successfully

print_receipt

Prints an image to a thermal receipt printer via ESC/POS protocol over serial or BLE.

Inputs:

• handle (Text) — serial or BLE connection handle
• image (Image) — image to print (dithered to 1-bit)
• width (Number) — printer width in dots
• service (Text) — BLE service UUID (empty for serial)
• characteristic (Text) — BLE characteristic UUID (empty for serial)

Output: printed (Boolean) — true if sent successfully

serial_close

Closes an open serial connection and releases the port.

Inputs:

• handle (Text) — connection handle to close

Output: closed (Boolean) — true if closed

serial_open

Opens a serial port connection and returns a handle for read/write operations.

Inputs:

• port (Text) — serial port name (e.g. COM3, /dev/ttyUSB0)
• baud_rate (Number) — connection speed in bits per second
• timeout_ms (Number) — read timeout in milliseconds

Output: handle (Text) — connection handle

serial_read

Reads data from an open serial connection with a configurable timeout.

Inputs:

• handle (Text) — connection handle from serial_open
• timeout_ms (Number) — read timeout in milliseconds
• max_bytes (Number) — maximum bytes to read

Outputs:

• data (Text) — received text data
• bytes_read (Number) — number of bytes received

serial_write

Sends text data over an open serial connection.

Inputs:

• handle (Text) — connection handle from serial_open
• data (Text) — text data to send

Output: bytes_written (Number) — number of bytes sent