BT900 Development Kit
Version 0.3
Embedded Wireless Solutions Support Center:
http://ews-support.lairdtech.com
www.lairdtech.com/wireless
10
Laird Technologies
Americas: +1-800-492-2320
Europe: +44-1628-858-940
Hong Kong: +852-2268-6567 x026
4.3.3
UART Interface Driven by External Source
UART interface driven by external UART source. The BT900 module UART interface (TX, RX, CTS, RTS) is
presented at a 2.54 mm (0.1”) pitch header (J10). To allow the BT900 UART interface to be driven from the
breakout header connector (J10):
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The development board must be powered from a DC jack (CN1) or AAA batteries (J7) and switch SW4
must be in DC position.
-
The FTDI device must be held in reset which is achieved automatically by removal of USB cable or SW4 is in
the DC position.
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Micro-DIP switch CON13 allows the four BT900 UART pins to be physically isolated as well from USB-UART
FTDI device. Physical micro-DIP switch body has text “ON” on the closed side. By default, CON13 is closed.
Figure 4: USB to UART Interface and Header to UART interface
J10 pin-out is designed to be used with an external FTDI USB to UART TTL (3.3V) convertor cables:
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
E.g. FTDI manufacturer part number for cable: TTL-232R-3V3
