PSoC supports CyFi low-power RF
By Robert Cravotta, Technical Editor - October 30, 2008
Developers can now use Cypress Semiconductor’s PSoC (programmable system-on-chip) devices with the company’s new, 2.4-GHz CyFi low-power RF product, which combines a PSoC processor running the CyFi star-network-protocol stack and the CYRF7936 CyFi transceiver. The approach employs DSSS (direct-sequence-spread-spectrum) modulation and the ability to move across 80 channels in the 2.4-GHz band to provide interference immunity. The CYRF7936 CyFi transceiver is available in a 40-pin QFN package. Evaluation and development kits that support the CyFi transceiver, including the CY3271 PSoC FirstTouch starter kit, the CY3271-EXP1 environmental-sensing kit, the CY3271-RFBOARD RF-expansion kit with CyFi technology, and the CyFi CY3210-CyFi development kit, are also available.
PSoC processors integrate a microcontroller with runtime-reconfigurable analog and digital circuits that can supply as many as 100 peripheral functions in one device. The devices include as much as 32 kbytes of flash memory, 2 kbytes of SRAM, an 8×8-bit multiplier with a 32-bit accumulator, power- and sleep-monitoring circuits, and hardware-I2C communications. The development tools enable designers to select configurable library elements for analog functions, such as amplifiers, ADCs, DACs, filters, and comparators, and digital functions, such as timers, counters, PWMs (pulse-width modulators), SPIs (serial-peripheral interfaces), and UARTs. The analog features include rail-to-rail inputs, programmable-gain amplifiers, and 14-bit ADCs with low noise, input leakage, and voltage offset.
The CyFi star-network-protocol stack is available as preconfigured firmware modules that require 8 kbytes of flash for a hub device and 5 kbytes of flash for a node device. Application code accesses the modules through an API (application-programming-interface)-based protocol stack that can handle as many as 250 nodes of asynchronous, bidirectional communications. The modules transparently provide active link and power management.
CyFi uses DSSS modulation to encode data so that, when the receiver encounters interference, it can recover a signal. A communication link can select a clear channel from the 80 narrow, 1-MHz channels that the transceiver supports. The implementation can dynamically increase power amplification to overcome interference. The implementation can also support a 1 Mbps, non-DSSS communication link in noise-free environments, and it can step down to 250- or 125-kbps DSSS when necessary to maintain the link. The system has a sleep current of 0.8 μA. The transceiver supports as much as 4 dBm of output power, and the receiver supports as much as −97 dBm of receiver sensitivity.
The CY3271 PSoC FirstTouch starter kit with CyFi low-power RF, a USB-thumb-drive kit, includes the PSoC IDE (integrated-development-environment) software, a sense and control dashboard for data collection, a PC dongle with RF, a multifunction board, an RF-expansion board with power amplifiers for long-range-wireless applications, and two battery boards. The kit supports evaluating the touch-, temperature-, lighting-, and proximity-sensing capabilities of the PSoC device. The CY3271-EXP1 environmental-sensing kit includes wireless pressure, humidity, temperature, and ambient-light sensors. The CY3271-RFboard RF-expansion kit, an add-on to the CY3271, provides two additional RF-expansion and AAA-battery boards. The CyFi low-power, general-purpose RF-development kit lets you prototype and debug with PSoC devices and CyFi transceivers. The kit includes two development boards, two PSoC modules, and three CyFi modules to build wireless-system applications.