RN-21-U Roving Networks Inc, RN-21-U Datasheet - Page 22

• Manufacturer Part Number: RN-21-U
• Description: MODULE BLUETOOTH 2.0/EDR CLASS1
• Manufacturer: Roving Networks Inc

Specifications of RN-21-U

• Frequency: 2.4GHz Center
• Data Rate - Maximum: 921kBaud
• Modulation Or Protocol: FHSS
• Applications: Bluetooth v2.0
• Power - Output: 16dBm
• Sensitivity: -86dBm
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Receiving: 60mA
• Current - Transmitting: 100mA
• Data Interface: PCB, Surface Mount
• Memory Size: 8MByte Flash
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7.3 LED Status
7.4 Optimizing for Latency or Throughput
7.5 Limitations of 7 Bit Data Mode
www.rovingnetworks.com
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a physical monitor of the actual voltage, and is not driven by software in the module.
The firmware automatically must make decisions on when to forward receive data coming into the UART RX
input out the RF link. The default mode is to optimize for throughput. In some cases, especially with
smaller close spaced incoming data packets, the data can get split, with partial packet forwarded and other
data coming later. Unfortunately, Bluetooth has algorithms that can cause significant latency between
packets ( > 10ms) at certain times. If the host protocol expects data to come as contiguous bursts and has
short timeouts, this can cause errors. There is another method of optimization, which will force the radio to
attempt to keep small bursts of data together. In this mode we optimize for latency. To enable this mode,
there is a special debug command. The command is “SQ,16”. This sets the latency bit in the firmware. To
disable this mode. Use the command “SQ,0”. The value of the register can be read with the “GQ”
command, and will read back as HEX, even though it is set as decimal.
Roving Networks firmware supports selectable 7 bit data mode, using the “S7,1” command.
Unfortunately the Bluetooth hardware does not support 7 bit data, so this function is accomplished in the
firmware application. While completely functional, the performance in 7 bit mode is less than ideal, because
software emulation is required to make this work. Hence, there is a noticeable latency and character per
second processing limit in this mode. Therefore it is not recommended that this mode be used if the desired
serial baudrate is greater than 9600 baud.
he YELLOW LED blinks when data is transferred on either the RX or TX pins of the DB9 serial port. It is
809 University Avenue
Configuring
Startup/Config Timer
Discoverable/Inquiring/Idle
Connected
•
MODE
Los Gatos, CA 95032
~ 22 ~
•
Tel [phone]
GREEN LED blink rate
10 times per second
2 times per second
Once per second
rn-bluetooth-um Version 4.77 1/24/2011
Advanced User Manual
Solid ON
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