Dallas, TX—Texas Instruments introduced a frequency-hopping spread spectrum (FHSS) wireless universal asynchronous receiver/transmitter (UART) chipset for the unlicensed United States 902-to-928 MHz frequency band. The Dolphin chipset is a cost-effective wireless interface solution that simplifies and speeds design of a variety of consumer, industrial and commercial applications, with all the hardware, software/firmware and support designers need to integrate a low-data-rate wireless link into their systems.

The chipset gives designers the benefits of a FHSS system to combat signal interference from other devices, a key issue for short-range wireless equipment due to the growing popularity of the unlicensed bands. In addition, FHSS enhances message privacy, provides better transmission range, and decreases the probability of transmissions being intercepted by other devices. These benefits make the chipset ideal for a multitude of applications such as utility automated meter reading; home and industrial automation and security; heating, ventilation and air conditioning system monitoring and control; consumer electronics; personal computer (PC) peripherals; personal medical devices; and hand-held electronic toys and games.

In the past, the system designer who wanted to implement a wireless link faced the task of designing a controller for the radio chip. With this chipset, the designer gains a true data-in/RF-out and RF-in/data-out solution, including the TRF6903 single-chip, multi-band radio frequency (RF) transceiver and the DBB03 digital baseband application-specific integrated circuit (ASIC). All aspects of data management and frequency-hopping are implemented in firmware on the DBB03, which includes the PHY, MAC and data link layer. A simple external host microcontroller (MCU) performs all system functions related to the end application. This gives the designer flexibility to select the external host from an array of catalog MCUs such as the ultra-low-power MSP430 product line. Since the interface between the DBB03 and the host MCU is a simple UART, end applications treat the RF link as a peripheral, making it flexible, scalable and easy to implement.

Other Key Features

• +2.2 to +3.6-VDC power supply
• FHSS, FSK
• UART host interface with programmable common baud rates provides a common interface for system partitioning
• Firmware supports both point-to-point and point-to-multipoint (broadcast) networks
• End applications interface to wireless link as a peripheral, shielding the application from the complex implementation details of a frequency-hopping system
• Fast frequency-hopping reduces power consumption and enables fast acquisition time of 70 milliseconds for 50 channels
• Two reference designs available: high transmit power (+23 dBm) for range up to 1 mile, and low transmit power (+7 dBm) with range up to 0.2 mile
• Both reference designs feature sensitivity of -101 dBm
• Over-the-air rates of 38.4 kbps
• Temperature range from -40C to +85C

The two-chip set consists of the TRF6903 RF transmitter and the DBB03 digital baseband ASIC. The most interesting part of the story rests with the baseband ASIC, which has on-board firmware fixed in ROM that incorporates the algorithms for frequency hopping and clock recovery. "It effectively does all of the housekeeping and control of the RF transceiver," explains Dave Wilson, manager for TI's HPL group. "So, instead of doing extensive digital baseband processing, designers simply need to write to a few registers to quickly set up the chips."

The team developed this chipset because they had customers asking for a low-cost ready-made solution that would allow them fast time to market with low-cost products for wireless automation, industrial control, as well as medical and consumer systems. The chipset can be teamed as a UART connection with any host microcontroller to handle applications level functionality.

One of the other things that designers can avoid by using this device is toeing the line to meet FCC guidelines on frequency hopping. "It's very easy to violate FCC guidelines for frequency hopping algorithms and how much output power you can transmit," warns Wilson. "Basically, if you use this chipset and follow our guidelines, you should sail through FCC certification."

The chipset competes with ZigBee, but the Dolphin chipset allows customer to develop their own proprietary system rather than using a standard. Are there any advantages to that? "We have a lot of customers who would prefer not to be compatible with ZigBee, so that their links can be more secure from competition," says Wilson. He adds that a proprietary product can be very simple with low overhead, and it allows systems designers to develop their own proprietary systems and realize competitive advantages.

Since it is a hardware manufacturer, the most challenging part about this project for TI was implementing the software. To accomplish this, they trained engineers to get up to speed on the current software, joined several RF boards and committees, and worked closely with their Beta customers.

Flexibility
But, by incorporating the algorithms on chip, don't we give up flexibility? The team notes that the chipset can provide flexibility even though the programming is mostly done. For instance, the firmware supports point-to-point, broadcast, and pseudo-mesh networks. Additionally, the network can be partitioned. Each transceiver features a unique transceiver ID, network ID, and system ID, and up to 65536 transceivers can be configured within a single system. With network partitioning, only transceivers with the same system ID, network ID and hopset can communicate.

Range? Data rates?
Range can be either several hundred feet or up to a mile in free space, depending on the product configuration. The version with an external power amplifier delivers up to +23-dBm output power and the one without delivers +7-dBm output power. Over the air data rates are specified at 38.4kbits/s. When the device is up and running, it is comparable in power consumption to other systems, but, when coming out of sleep mode it offers the advantage of a 200μs channel lock time.

The chipset comes with an evaluation board, user guide, evaluation software, and protocol documents. Gerber files, reference designs, schematics, and BOM are available on the company website.

The chipset is priced at $4.50 each in 1,000-piece quantities. It is available now in production quantities. Click here for the Dolphin Chipset data sheet.