A discrete multichip solution typically requires additional external components in addition to separate microcontroller and radio chips. This adds additional size and cost to the design. By using an integrated solution, the design can be extremely small, consume less power, cost less, and take less time to develop. Figure 4 shows a block diagram of an eight-bit microcontroller with an integrated 2.4 GHz radio. Observe that due to the integration of the two chips the interface between the microcontroller and the radio is completely internal, which reduces the number of external pins required or frees external pins to become generic I/O pins instead of being dedicated to the radio interface.

Integrated solutions are able to take advantage of the tight coupling between the microcontroller and the radio to create an easy-to-use firmware library for radio access. Some solutions even provide a complete protocol stack that provides a robust two-way link between devices. Depending on the target application the right protocol may be Bluetooth, wirelessUSB or Zigbee. By providing a complete protocol stack customized for the specific radio and microcontroller these solutions make it easy to create a connection between two or more devices. A simple API, such as the one shown below, is used to interact with the radio. After creating the connection the protocol will send packets to the target device, retransmitting the packets if an error is detected. If a connection is lost to the target device the protocol will re-establish the connection or find another route to the target device.

protocol_init()

protocol_create_connection()

protocol_send_packet(int packet_length, char* packet)

protocol_get_packet(int max_packet_length, char* packet)

Figure 5 shows an example of a protocol state machine that handles creating a wireless connection, and provides guaranteed packet delivery and interference immunity, without requiring additional design effort by engineers. This allows the engineers to treat the wireless link like a wired serial bus such as SPI, UART or I²C.

With the integration of radio and microcontroller it is now trivial to create small wireless temperature sensors that can be placed in each room of the house, with each sensor periodically reporting its temperature to the main thermostat in order to more accurately control the heating and air conditioning in the home. A floodlight that lights up the driveway can now be connected to additional motion detectors covering the front walkway and side of the house so that the floodlight turns on when you walk out the door instead of requiring you to walk in darkness to the driveway before it turns on.

As Meg pulled into her garage, she smiled as she looked forward to watching her favorite show on her new plasma TV and wished that somehow her intelligent garage door opener would also heat up the TV dinner in a microwave and serve it on her table! Not a reality yet, but dream on since now is the time to bring those dreams to reality.

Deepak Sharma is senior product marketing manager-wireless for Cypress. He joined the company in 1998 as a marketing engineer and has progressed over the years to manage several products. He managed PLDs, datacom and video products in the DCD division. In early 2005, he moved into the CCD division to take over the wireless portfolio. His expertise is in marketing and brand strategy for hi-tech products with experience in organizational and business strategy. He holds an M.B.A. from Rochester Institute of Technology (NY) and a B.Tech from B.I.T.S. (Pilani), India.

Ryan Woodings is a staff software engineer at Cypress Semiconductor, specializing in short-range wireless protocol design for the company's wirelessUSB products. He has six years experience in short-range wireless technologies including IrDA, Bluetooth and wirelessUSB. Woodings holds a B.S. and M.S. in Computer Science from Brigham Young University.

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