Product Description

Communicate with other devices or systems over AC or DC power lines. The PLM Shahara is the next tier of the JARViE PLM development platform. It is a standalone miniature PLM development module measuring 2" x 2" X 1.5"; perfect for embedding into DIY or prototype designs. The Shahara houses an onboard ATmega328p MCU for custom firmware development in the popular Arduino and Atmel Studio development environments; enabling one to create a custom smart home device and or powerline smart home network. An onboard +5V AC/DC converter powers digital circuitry directly from the 120 or 240VAC input wires that the module communicates over. This technology enables applications including but not limited to: lighting control, home appliance control, energy/heating control and up to 3,000 feet data transmission home power networks.

Like the JARViE Demo Board and Arduino Shield, the Shahara highlights the NXP TDA5051A home automation modem which allows all three devices to communicate with one another when placed on the same power bus. The TDA5051A is an amplitude shift key (ASK) power line modem that operates up to 1200 bits per second (bps) from a single +5VDC supply. The receiver portion of the modem employs automatic gain control (AGC) at its input and the transmitter has output power overload protection. An 8-bit A-to-D converter and a narrow digital filter follow the AGC stage in the receiver. The TDA5051A power line modem application solution is compliant with US FCC (Federal Communication Commission), Industry Canada, Japan MPT, and European CENELEC EN50065-1 regulations for signaling in the 125 kHz to 140 kHz and the 95 kHz to 125 kHz frequency bands.

How It Works

Each Shahara has an NXP TDA5051a powerline modem IC. This modem takes in a digital message from the MCUs UART bus and translates this digital message into an equivalent analog message. Additional circuitry on the Shahara board sends the analog message over the 120/240VAC of your home, if the Shahara is connected to a home outlet. Ideally, the analog message will be broadcasted across all 120/240VAC wires of your home that share the same circuit (to all home outlets on the same circuit), so another board connected to another home outlet on the same circuit will hear this message. The Shahara has special filtering to only receive messages sent by other JARViE Demo, Shield and or Shahara powerline boards and rejects all other noise or communications between non JARViE boards. Once a Shahara board receives an analog message sent over the home power lines, it converts it to an equivalent digital message and sends it to an MCU over its UART bus. Additionally, the Shahara can communicate over DC powerlines as well.

Product Features

• Communicates over 0 to +48VDC or 0 to 240VAC power buses
• Onboard 100-240VAC to +5VDC AC/DC converter to power MCU (board does not require an external DC power supply)
• Optically coupled zero cross detection for system synchronization and or line frequency measurements
• Breaks out 4 MCU GPIO signals that can be configured as two ADC channels and or an I2C bus and or general I/O
• Onboard relay that routes the AC HOT wire to the main input connecter in-order to switch power to an appliance
• Galvanic power line isolation via high-frequency transformer
• 1200 baud data rate (default)
• Full digital carrier generation and shaping
• High clock rate of 6-bit D/A (Digital to Analog) converter for rejection of aliasing components
• Fully integrated output power stage with overload protection
• Automatic Gain Control (AGC) at receiver input
• 8-bit A/D (Analog to Digital) converter and narrow digital filtering
• Digital demodulation delivering baseband data

Basic Home Automation Architecture

The JARViE PLM can communicate over +48 VDC max or up to 240 VAC power lines. The figure below diagrams a home application. The master and slave devices employ an MCU and the JARViE PLM. During a data transmission event (device master sending out data to slave devices), the MCU sends the data to be transmitted to the PLM's TDA5051A via a UART interface. After internal processing, the PLM broadcasts the data over the power line to all slave devices using a modulated carrier wave. During a data reception event (slave device receiving data from master), the PLM's TDA5051A converts the carrier wave into digital data. The digital data is fed into the MCU's UART interface for interpretation.

DC Power Line Application

The above diagram illustrates how the PLM Shield should be connected to a DC power line. In this diagram, the DC power source can be a switch-mode power supply, solar panels with converted DC output, batteries, super capacitor, etc. The DC power source should not exceed +35 VDC. When using a switch-mode power supply, it is best to filter the output to achieve the best powerline telecommunications. L1 = 100 uH and C = 470 uF forms a low-pass filter that prevents power supply noise from interfering with powerline communications. The filtering components are likely not required when using batteries or capacitors as the power source. The impedance of C decreases as freq. increases so a choke (L2 = 100 uH) is recommended to prevent the capacitor from overloading/shorting the 1200 Hz powerline communications. Using batteries and capacitors as the DC power source will have the same overloading affect, so a choke is recommended for these sources as well.

Complete Shahara Demo Kit

The complete demo kit provides everything needed to quickly get started with communicating over AC or DC power lines. There's a huge value add that comes with purchasing the kit; all the hardware is proven and software examples are available on GitHub. This gets the developer learning PLM technology on day one and NOT spending days specifying and purchasing hardware and or developing firmware.

Kit contents include,

• JARViE Shahara Powerline Board (2)
• 120VAC Power Cable (2)
• Sparkfun USB Pocket AVR ISP Programmer (optional) (1)
• PM2425 AC Wall Plug Enclosure (Not included)
• 739W-X2/03 AC Snap-In Receptacle (Not included)

Getting Started

All info (product documentation, firmware, etc.) for quickly getting started is on the device GitHub page.

Safety Warning

The non-insulated high voltages that are present when operating this product, constitute a risk of electric shock, personal injury, death and/or ignition of fire. This product is intended for evaluation purposes only. It shall be operated in a designated test area by personnel that is qualified according to local requirements and labor laws to work with non-insulated mains voltages and high-voltage circuits. This product shall never be operated unattended.

The board needs to be connected to mains voltage. Touching the reference board during operation must be avoided at all times. An isolated housing is obligatory when used in uncontrolled, non-laboratory environments. This isolation is not according to any regulated norm. Galvanic isolation of the mains phase using a variable transformer is always recommended.

JARViE is NOT liable for any mishaps that occur while using this board. User must consider and take proper safety precautions while working with high-voltages.

Data Transmission

The following image shows the DATA_IN to Tx carrier output delay. The blue trace is a 1 kHz square wave driving the PLM's TDA5051A modem DATA_IN input. The yellow trace is the modulated ASK carrier wave transmitted to all PLMs on the power line network. The capture shows that there is approximately a 170 microsecond delay between setting the DATA_IN input and Tx carrier wave generation.

Data Reception

The following image shows the Rx carrier input to DATA_OUT output delay. The blue trace is the modulated ASK signal received through the AC inputs on the JARViE PLM. The yellow trace is the digital TDA5051A DATA_OUT signal that can be interpreted with an MCU or equivalent UART compliant device. The capture shows that there is approximately a 180 microsecond delay between Rx carrier wave reception and the DATA_OUT output.

AC Zero Cross Detection

The main purpose of the PLM zero cross detection circuitry (ZCD) is to provide a method to synchronize devices to one another. The intent is to not have to share a clock between devices that are meters away. The output of the ZCD goes from 0 to +5V making it compatible with MCUs. By pairing the PLM with an MCU, the ZCD output can be used to trigger event timers, create task schedulers within a PLM network and or send messages when noise on the power line is smallest for best communication results (zero crossing point). The ZCD can also be used to measure the frequency of the AC power line.

• A – 120 VAC zero cross point. Signal begins to rise to maximum amplitude but the PLM H11AA1 bi-directional optocoupler is off so zero cross signal remains HIGH (+5V) due to pull-up resistor.
• B – 120 VAC rises high enough to bias NPN transistor in optocoupler pulling the zero cross detection signal LOW (0V).
• C – 120 VAC zero cross point. Signal begins to fall to minimum amplitude. H11AA1 optocoupler is off so zero cross signal remains HIGH (+5V) due to pull-up resistor.
• D – 120 VAC falls low enough to bias NPN transistor in bi-directional optocoupler pulling the zero cross detection signal LOW (0V).

Why did you make it?

This product was made to provide a reliable and low-cost solution for leaping into Smart Home and Internet of Things (IOT) applications quickly.

What makes it special?

The PLM Shahara is a miniature PLM module that enables devices to communicate over meters of 0 to 240 VAC or +48V max DC power lines removing the need to have devices closely tethered together with more than two wires. Devices being able to communicate over meters of AC or DC power line enables one to develop a mesh network of two or more distributed devices, each having unique functions. Devices that potentially allow one to close your garage, turn-off a downstairs TV or monitor the power consumption of home appliances while lying in bed.