Datasheet RN42, RN42N (Microchip) - 9

link to page 8
RN42/RN42N FIGURE 2-5: RN42 HOST PCB EXAMPLE LAYOUT
RN42 No Copper Best RN42 in these RN42 RN42 areas Okay Okay Okay
2.5 External Antenna Types (RN42N)
Using the module in HCI mode enables designers to implement profiles that are not natively supported on The RN42N module’s antenna pin (pin 26) provides a the Bluetooth module. 50-ohm impedance to external antennas. Pin 25 can connect directly to a coaxial cable or to an antenna
Note:
HCI mode is only available by ordering connector such as a U.FL or reverse polarity SMA. part RN42HCI and RN42HCI for UART interface; or RN42U and RN42U for USB The PCB trace from pin 26 to the coaxial cable or con- interface. nector should be less than 0.2 inches (5 mm) for mini- mum loss and the best impedance match. If the PCB trace is longer, it should be a 50-ohm impedance Microchip offers HCI mode in two hardware interfaces: microstrip trace. Connect adjacent ground pins 25 and • HCI over UART (RN42HCI-I/RM) 27 to a low-impedance ground on the host PCB and the • HCI over USB (RN42U-I/RM) antenna connection. Figure 2-4 gives example host PCB layout to a U.FL connector. 2.6.1 HCI OVER UART In this mode, the hardware interface between the host
2.6 HCI Mode
processor and the Bluetooth module is the UART con- figured at 115.2Kbps. The UART hardware flow control Microchip offers the Host Controller Interface (HCI) mode in addition to the standard operational mode of its signals are required between the host processor and Bluetooth modules (standard mode refers to the on- the Bluetooth module for the HCI interface to work. board stack running on the module). Failure to do so can cause the host processor and the Bluetooth module to become out of sync and break the In HCI mode, the on-board stack is bypassed and the Bluetooth link. module is put in a state that runs the Bluetooth base- band. The HCI provides a command reference inter- 2.6.2 HCI OVER USB face to the baseband controller and the link manager, In this mode, the hardware interface between the host and provides access to the hardware status and control processor and the Bluetooth module is the USB. In this registers. This interface provides a uniform method for architecture, the Bluetooth module is the USB slave accessing the Bluetooth baseband capabilities. and the host processor is the USB host. In this mode, the Bluetooth stack is no longer on-board Using the USB interface offers the advantage of a the module. It is offloaded to the interfacing host pro- faster data link between the Bluetooth module and the cessor. The Bluetooth module is used as a radio, per- host processor. With this interface, it is possible to forming the lower level MAC functionalities, while the achieve Bluetooth’s theoretical maximum throughput of application stack runs on the host processor. 3 Mpbs.  2015 Microchip Technology Inc. DS50002328A-page 9 Document Outline Class 2 Bluetooth® Module with EDR Support Table of Contents 1.0 Device Overview 1.1 MCU Interface 1.2 ASCII Command and Data Interface TABLE 1-1: Environmental Conditions TABLE 1-2: Electrical Characteristics TABLE 1-3: Module Dimensions TABLE 1-4: Radio Characteristics TABLE 1-5: Digital I/O Characteristics TABLE 1-6: Pin Description 2.0 Application Information 2.1 Reset Circuit 2.2 Factory Reset Using GPIO4 2.3 Connection Status TABLE 2-1: GPIO5 Status TABLE 2-2: GPIO2 Status 2.4 Module Mounting Details 2.5 External Antenna Types (RN42N) 2.6 HCI Mode 2.7 Soldering Recommendations 2.8 SPI Interface 2.9 Bluetooth SIG QDID 2.10 Application Schematic 3.0 Regulatory Approval 3.1 United States 3.2 Canada 3.3 Europe TABLE 3-1: RN42 European Compliance Testing 3.4 Australia 3.5 New Zealand 3.6 Japan 3.7 Korea 3.8 Taiwan 4.0 Ordering Information TABLE 4-1: Ordering Information(1) Worldwide Sales and Service