NCN5100 Arduino Shield Evaluation Board User s Manual EVBUM2715/D INTRODUCTION www.onsemi.com 1 KNX 3 is a popular open home and building automation standard . ON Semiconductor has a series of transceivers that handle the low EVAL BOARD USERS MANUAL level communication. The NCN5100ASGEVB evaluation boards are Arduino-compatible shields enabling rapid prototyping with a microcontroller of choice. All external components necessary for operating the transceivers are present on the shield. Plug it in a Arduino-compatible development kit and start developing FEATURES Arduino Uno V3 compatible connectors Compatible with a wide variety of microcontroller development boards Four on-board buttons/LEDs to build a dimmer application Available in UART- and SPI-version Fully KNX-compliant transceiver Easily get started with KNX 2 Figure 1. NCN5100AS-1 Evaluation Board Maximum bus current up to 40 mA Two high-efficiency DC-DC converters 3.3 V fixed output 1.2 V to 21 V variable output Integrated 20 V linear regulator output OVERVIEW The NCN5100ASGEVB boards come in three variants containing the NCN5110, NCN5121 and NCN5130 transceivers. The NCN5110 is a bit transceiver and all the timings are handled by the microcontroller. Both the NCN5121 and NCN5130 also implement the MAC layer, reducing the software development effort. All critical timings are handled by the transceiver. All transceivers include two high-effciency DC-DC converters. One fixed converter generating 3.3 V, supplies the transceiver and other optional peripherals such as a microcontroller. The second DC-DC Figure 2. NCN5100AS-2 Evaluation Board converter has an adjustable output voltage ranging from 1.2 V to 21 V and can be used to supply peripherals such as, relays, a display, etc.. The Arduino shield form factor makes it easy to start developing just plug the shield into a compatible microcontroller board and start coding. Thanks to the on-board buttons and LEDs, it is not necessary to plug in additional shields to start testing. A simple dimmer application can be set-up in no time with only the KNX Arduino-shield. 1 EVBUM2715/D Fan-in Both the NCN5121 and NCN5130 come with an SPI and Every device connected to the KNX-bus will draw current UART communication interface. The latter is fully from the bus to supply the application. The KNX standard TP-UART compatible, enabling the use of existing specifies the current should be limited to the real need. For compatible software. every KNX-device the maximum current draw is specified The boards are 2 layer PCBs with single-sided assembly, in its datasheet according to the fan-in-model 1 . The demonstrating that it is possible to easily develop low-cost fan-in-model is used to determine how many devices can be applications. connected to one physical segment of the bus. All the EVALUATION BOARD OVERVIEW ON Semiconductor KNX transceivers contain a built-in The main connectivity to the evaluation board is provided mechanism to keep the draw within the value specified in its through the Arduino V3 headers which can be seen in datasheet. This makes sure that the device complies with the Figure 1. This has the advantage that the board is compatible standard. with a wide variety of microcontroller development boards. The fan-in pin sets the maximum current drawn from the Refer to Appendix C, Table 6 for a list of tested platforms. bus. The transceiver will actively keep the current below the set limit. The KNX-Bus Both transceivers (NCN5121 and NCN5130) have two The KNX-bus consists of a twisted pair cable providing pre-defined fan-in modes. These can be selected by either both data and power. The voltage on the bus varies between connecting the fan-in pin to GND or leaving it floating. 21 V to 32 V (V in Figure 3). Communication on the bus DC Leaving it floating, the maximum bus current is limited to is done at 9600 baud asynchronously. A logic one is 10 mA. Tied to GND the limit is set to 20 mA. represented by the DC-level on the bus staying constant. For The NCN5130 also offers an external fan-in mode. In this a logic zero, the bus is pulled 3 V to 10 V below the DC-level mode the current limit can be set linearly from 5 mA to first. This is called the active pulse which has a duration of 40 mA. This is achieved by connecting a resistor with typically 35 s. Following immediately after is the avalue of 10k to 93.1k to the fan-in pin. The equalisation pulse. During this time, the voltage can swing fan-in-model 1 specifies discrete current classes. When up to 13 V above the DC-level and will decay exponentially designing the application and defining the current in 69 s. consumption, the next higher value of one of the classes must be selected. According to section 3.3 of the KNX test V BUS specification 2 the maximum allowed bus current consumption for a fan-in-model of 10 mA is 12 mA. For other fan-in models it is allowed to scale this value V eq accordingly. For example, a 20 mA fan-in-model allows to V end V DC draw 24 mA from the bus. V act Table 1. RECOMMENDED FAN-IN RESISTOR VALUES Active Equalisation t pulse pulse I Current Class bus,lim (Typical Values) (Note 1) R 3 35 s 69 s 11.4 mA 10 mA Figure 3. Waveform Seen on the Bus when 0 22.3 mA 20 mA Transmitting a Logical Zero 10 k 43.9 mA 40 mA Figure3 shows a typical waveform on the bus 13.3 k 33.0 mA 30 mA representing a logical zero. 20 k 22.1 mA 20 mA 42.2 k 10.7 mA 10 mA 93.1 k 5.1 mA 5 mA 1. According to the fan-in-model 1 . Linear range 40 mA 5 mA 20 mA 10 mA Pre-defined External fan-in Pre-defined fan-in fan-in Only for NCN5130 R 3 0 2 k 10 k 93.1 k 250 k Figure 4. The Different Fan-in Settings www.onsemi.com 2