Datasheet

RN-41-SM/RN-42-SM Data Sheet
www.rovingnetworks.com 7/12/2010
809 University Avenue • Los Gatos, CA 95032 • Tel [phone] • [e-mail]
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Hardware Connections and Power
Placing 3.3Vdc into the PIO’s outputs will permanently damage the radio modules. The failure mode is short
across GND and VCC. Use a 10KΩ resistor in series or a 10KΩ pull up resistor for input and output PIO’s
respectively.
• Make sure to connect a common ground when using the external TX, RX inputs 0 – 3.3Vdc.
• For a 3 wire DB-9 interface (tx, rx, gnd only) connect/short CTS to RTS, Factory default is hardware flow
control enabled CTS and RTS connected.
• When using a 5.0Vdc Input, PIO’s require a voltage divider. A good choice is 10K ohm series with 20K to
Ground. PIO’s are 0-3.3Vdc not 5 volt tolerant.
Hardware Communications Connections for Modules
RN-41-SM / RN-42-SM TX 

 RX of the application Micro Controller Unit (MCU)
RN-41-SM / RN-42-SM RX 

 TX of the application Micro Controller Unit (MCU)
RN-41-SM / RN-42-SM RTS 

 CTS of the application Micro Controller Unit (MCU)
RN-41-SM / RN-42-SM CTS 

 RTS of the application Micro Controller Unit (MCU)