Standards like ZigBee and 802.11n provide performance and flexibility. However, their overhead and costs may be unnecessary for many applications, especially for low-power devices. Applications may need dozens of nodes that a range of proprietary options can handle easily. This approach locks designers into a particular platform, but this can be an advantage. There are almost as many options as there are wireless microcontroller vendors.
Texas Instruments started the trend many years ago (see “$1 Arms And $20 Development Kits”) with the original eZ430-F2013 (Fig. 1). Its latest incarnation shows up in the eZ430-Chronos (see “Low-Cost Kits Make Evaluation Easier”).
TI has plenty of wireless options, including 802.15.4 and ZigBee. But it also has the SimpliciTI network protocol, which is a proprietary, low-power protocol targeting networks under 100 nodes that have a low data rate and low communications duty cycle. It uses minimal resources, allowing it to run on TI’s MSP430.
Even though it’s a low-overhead system, SimpliciTI can handle a multihop peer-to-peer (P2P) network. Range extenders can handle up to four hops. Security is optional, like many proprietary protocols. This is important for applications such as metering and security systems.
CyFi FOR CONTROL
Cypress Semiconductor has a flexible line of microcontrollers called PSoC. Its CyFi development kit (Fig. 2) is based on the PSoC 1, which is now complemented by the 8051-based PSoC 3 and ARM-based PSoC 5 (see “Field-Programmable I/O Augments 8- And 32-Bit Microcontrollers”). The newer platforms easily handle the protocol.
The 2.4-GHz RF solution employs direct-sequence spread spectrum (DSSS), allowing it to operate in environments with other RF gear. It implements a star network protocol using only 6 kbytes of code for a regular node and 8 kbytes for a hub. Active power management keeps the chips sipping less often from the battery trough.
Microchip’s MiWi protocol is built on 802.15.4. Serial peripheral interface (SPI) modules like Microchip’s MRF24J40 implement the MiWi protocol (Fig. 3). It offers much of the flexibility of ZigBee. But like SimpliciTI and CyFi, developers get the protocol stack for free.
Platforms like ZigBee are a basic requirement for many applications. But if that box is unchecked, one of these alternatives may be more effective.