RN-131G
rn-131-um.pdf 5/14/2009
www.rovingnetworks.com
Phone 408-395-6539
- 4 -
2
Hardware Interface
See the RN-131 data sheet on the Roving Networks website for technical specifications and
layout information. (Document rn-131-ds.pdf
)
2.1
Power
There are two options for powering the RN-131G module directly.
1.
DC SUPPLY: Apply 3.3 VDC power to VBATT (pin 20), AND V3.3IN (pin 21)
Tie 3.3VREG-IN (pin 18) to GROUND. 3.3V-REG-OUT (Pin 17) leave floating.
2.
BATTERY: Apply battery = 1.8 to 3.3VDc to VBATT (pin 20). V3.3IN pin 21 = floating.
Tie pin 17 to pin 18. (this enables the on board battery boost 3.3V switcher).
2.2
Reset
Reset is active LOW and is optional/does not need to be connected. The reset pin is 3.3V
tolerant and has an internal pullup of 100K to the VBATT. There is also a built in voltage
brownout monitor.
2.3
UART
•
Connect a common ground when using the external TX, RX inputs.
•
For a 3 wire DB-9 interface (tx, rx, gnd only) Factory default is hardware flow control
disabled, CTS and RTS are not required.
•
When using a 5.0Vdc Input, PIO’s and UART pins require a 10K ohm series resistor. PIO’s
are 0-3.3Vdc not 5 volt tolerant.
Warning: Do NOT exceed the voltage ratings on the 3.3V pins, damage to the module will
result.
Important Notes:
#1: The Sensor inputs SENS0-7 are extremely sensitive to over voltage. Under no
conditions should these pins be driven above 1.2VDC. Placing any voltage above
this will permanently damage the radio module and render it useless.
#2: Placing 5VDC or any voltage above 3.3Vdc into the VDD pins of the module will
permanently damage the radio module.
#3: Placing 3.3Vdc into the PIO’s while they are set as outputs will permanently
damage the radio modules. The failure mode is a short across GND and VCC. Use a
10KΩ resistor in series or a 10KΩ pull up resistor for input and output PIO’s
respectively.
