SoC Uses Powerline Communications to Control Embedded Applications

Jun 1, 2010 12:00 PM
SAM DAVIS, Editor-in-Chief, PET

REFERENCE DESIGNS

Cypress provides reference designs for a range of powerline voltages including 110V/240V ac and 12V/24V ac-dc. The PLC system can provide data communication over other ac-dc powerlines as well with the appropriate external coupling circuit. The 110Vac and 240Vac designs comply with the powerline usage regulations.

Cypress also offers multiple evaluation and development kits. The CY3272 High Voltage Powerline Communication Evaluation Kit and CY3273 Low Voltage Powerline Communication Evaluation kits are compliant with FCC and CENELEC standards and includes an evaluation board, quick start guide, multiple cables, a USB cable, a 12V ac power adapter and a CD with test software, datasheets, a user guide, an application note, schematics and Gerber files.

The CY3274 Programmable High Voltage Powerline Communication Development Kit (Figure 4) and CY3275 Programmable Low Voltage Powerline Communication Development Kit enable system design using CY8CPLC20 devices. The CY3276 Programmable High Voltage Powerline Communication Development Kit and CY3277 Programmable Low Voltage Powerline Communication Development Kit are targeted for lighting application system design using CY8CLED16P01 devices.

Among the development tools are:

• Free Development Software (PSoC Designer™)
• Full Featured In-Circuit Emulator (ICE) and Programmer
• Full Speed Emulation
• Complex Breakpoint Structure
• 128 KB Trace Memory
• Complex Events
• Compilers, Assembler, and Linker

SPECTRUM ANALYSIS

A spectrum analyzer was used to measure quasi-peak and average PLC signals, taken over a period of one minute. The test was conducted with both 110V and 230Vac mains. The PLC modem had the following settings for these measurements:

• Transmit gain set to 125 mVp-p
• Clocking mode set to external oscillator
• Baud rate set to 2400 bps with a 1.5kHz bandwidth

A CY8CPLC10 chip was used in an internal test mode to continuously transmit data. The external I2C connection was not used to initiate transmission, because the unshielded connecting cable can generate excessive noise. In normal user applications, the I2C connection is usually on the same board and the system is in an enclosure. The graph in Figure 5 shows the results of the conducted emissions test with the chip mounted on a CY3272 evaluation board.

The dark red and blue lines show the output spectrum from 10 kHz to 24 MHz based on the quasi-peak and average measurements taken at the mains terminals of the device respectively. The light red and blue lines show the allowed limit of the spectrum as given in the EN50065-1:2001 standard for quasi-peak and average measurements, respectively.

The chip's peak output level is measured as 119.04 dBµV on the mains output of the board. The limit of devices that transmit in the frequency range of 95 kHz to 148.5 kHz is 122 dBµV. The peaks of the first and second harmonic signals are 57.67 dBµV and 39.59 dBµV, respectively.

NOISE IMMUNITY

Tests on a Reference Design Board illustrated the immunity of the CY8CPLC10 programmable system-on-chip to white noise and narrowband interference in the PLC communication frequency band. The interfering signals were chosen because they were known to be critical to the functioning of the PLC boards. The following types of interference were used:

• White Noise
• Single Tone Continuous
• Single Tone Burst
• AM Modulated

Cypress' PLC solution allows designers to integrate system functions and powerline communication functionality on the same chip. Before, system designers had to purchase different chips for their system functions. The basis for the Cypress solution is a SoC platform that allows designers to implement highly integrated designs with minimum components. This approach pays special attention to the PLC's performance, making it reliable to use under a variety of conditions.

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