BT 900 User Manual download pdf (Page 9)

BT900 Development Kit

Version 1.0

Embedded Wireless Solutions Support Center:

http://ews-support.lairdtech.com

www.lairdtech.com/wireless

Laird Technologies

Americas: +1-800-492-2320

Europe: +44-1628-858-940

Hong Kong: +852-2268-6567 x026

 VCC_IO is wired to the header connectors (JP2, JP3, JP4, JP5) via R29 and can be used to power external

devices sensors.

4.2 Reset Button

The development board has a reset button (SW2). The reset is active low (SW2 pushed down). To view its location,

refer to Error! Reference source not found..

4.3 4-Wire UART Serial Interface

The development board provides access to the BT900 module 4-wire UART interface (TX, RX, CTS, RTS) either

through USB (via U9 FTDI USB-UART convertor chip) or through a breakout header connector J10. Refer to Figure 4.

Note: BT900 module provides 4-wire UART interface on the HW and the other four signals (DTR, DSR, DCD, RI)

which are low bandwidth signals can be implemented in a

smart

BASIC application, using any spare digital

SIO pins.

4.3.1 UART Mapping

UART connection on the BT900 series module and FTDI IC are shown in table below. Refer to Figure 4 to see how the

BT900 series module UART is mapped to the breakout header connector (J10).

Table 1: UART mapping

BT900 SIO

BT900 Default function

FTDI IC UART

SIO.1

UART_TX (output)

USB_RX

SIO.0

UART_RX (input)

USB_TX

SIO.2

UART_RTS (output)

USB_CTS

SIO.3

UART_CTS (input)

USB_RTS

Additional SIO pins are also routed to the FTDI chip via a switch block. For example, the nAutoRUN input pin on the

module can be driven by the DTR output pin of the FTDI chip. This allows testing the $autorun$ application on boot.

4.3.2 UART Interface Driven by USB

 USB Connector. The development kit provides a USB Type mini-B connector (CON4) which allows connection

to any USB host device. The connector optionally supplies power to the development kit and the USB signals

are connected to a USB to serial convertor device (FT232R), when SW4 is set to ‘USB’ position.

 USB – UART. The development kit is fitted with a (U9) FTDI FT232R USB to UART converter which provides

USB-to-Virtual COM port on any Windows PC (XP or later). Upon connection, Windows auto-installs the

required drivers. For more details and driver downloads, visit http://www.ftdichip.com/Products/FT232R.htm.

 UART interface driven by USB FTDI chip. In normal operation, the BT900 UART interface is driven by the FTDI

FT232R USB to UART converter in the development board. This is used for the BT900 series module

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BASIC runtime engine FW upgrade or to load

smart

BASIC application script.

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BT 900 User Manual Page 9

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