# Wireless UART

The wireless UART can be used to communicate between two PCs via a RF link, or to communicate between a PC and an autnomous sensor/actor node. The WUART application starts on a fixed channel and is automatically in a transparent data mode.

Note:
  The programm documentation of the firmware can be found in this section.

After a reset of the firmware, the programm prints a startup message and is then in the data transmission mode.

The startup message can be used toidentify the baudrate, that is configured at compile time. The startup message is one line of text and contains the following information:

    Wuart 0.3 chan=11 radio 83.4 cfg F
          |    |         |        |
          |    |         |        +... configuration read from flash (F) or EEPROM (E)
          |    |         +............ values of transceivers PART_NUM.VERSION_NUM register
          |    +...................... configured IEEE radio channel
          +........................... application version

After printing this startup message the WUART application is in data transmission mode, that means that the payload of incoming frames is printed on the serial interface and incoming data from the serial interface are sent as IEEE 802.15.4 frames.

## Configuration

The wireless UART has a configuration menue, that can be reached by typing the Hayes 302 break sequence: `pause +++ pause`. After entering this sequence the following menu will appear in the terminal window:

    MENU:
    [a] node address: 0x5
        peer address: 0x4
    [c] channel:      11
    [r] reset changes
    [e] save and exit
    [q] discard chadiscard changes and exit

Pressing the letter in the square brackets will query you at a prompt for a new parameter value. Pressing "e" stores the current settings in the EEPROM. After pressing "e" or "q" the application returns to data mode.

## WUART Protocol

The wireless UART uses the simple P2P air protocol. It assumes IEEE 802.15.4 data frames with 16 bit adressing and PAN-ID compression. The following frame contains just one payload byte (7), the ASCII letter 'c':

    Frame Bytes:
    0000  41 88 02 42 42 07 00 06 00 40 55 63 e9 b1         A..BB......
          +---+ ++ +---+ +---+ +---+ +---+ ++ +---+
           (1)  (2) (3)   (4)   (5)   (6)  (7) (8)

    Protocoll Data:
    Frame 282: 14 bytes on wire (112 bits), 14 bytes captured (112 bits)
    IEEE 802.15.4 Data, Dst: 0x0007, Src: 0x0006
    P2P Protocol Data
        FCF:   0x4188               (1)
        Seq:        2               (2)
        pan:   0x4242               (3)
        to:    0x0007               (4)
        from:  0x0006               (5)
        cmd:   P2P_WUART_DATA (64)  (6a)
        mode:  85                   (6b)
        sdata: c                    (7)
        FCS:   0xb1e9               (8)