Hartcran House, 231 Kenton Lane, Harrow, Middlesex, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233, www.radiometrix.com CLX2 PRELIMINARY Issue A, 10 April 2012 19200 baud serial wireless modem The CLX2s a 19,200baud half-duplex serial radio modem module operating on licence-exempt European 433.05-434.79MHz SRD band. CLX2 is an intermediate level OEM radio modem which is in between a raw FSK radio module like BiM2G and a sophisticated OEM radio modem like RPM2A. It takes care of preamble, frame synchronisation and error checking. Features Figure 1: CLX2-433-19 Conforms to EN 300 220-2 and EN 301 489-3 SAW front-end filter Small size Low cost Direct interface to microcontroller UART Serial modem baud rate at 19,200bps (half-duplex) Applications Home/Industrial Automation Vehicle Sensor Monitoring Telemetry Data Logging Systems Security Systems for Home/Industrial In-building environmental monitoring and control Sports and Performance Monitoring Technical Summary Operating frequency: 433.92MHz (default) Modulation: 34.5kbps NRZ FSK UART interface: 19,200bps, 8 data bits, None Parity, None Flow Control Supply: 3.3V at 23mA transmit, 13mA receive and <2mA standby Transmit power: +3dBm (2mW) Receiver sensitivity: -95dBm (for 1% BER) 32 byte data buffer 40 x 14 x 5mm Radiometrix Ltd CLX2 Data Sheet page 1 Figure 2: CLX2 block diagram Radiometrix Ltd CLX2 Data Sheet page 2 The radio / datastream interface A 32 byte software FIFO is implemented in both the transmit and receive code. At the transmit end this is used to allow for the transmitter start up time (about 4ms), while on receive it buffers arriving packets to the constant output data rate. All timing and data formatting tasks are handled by the software. The user need not worry about keying the transmitter before sending data: the link is entirely transparent. For transmission across the radio link data is formatted into packets, each comprising 6 bytes of data, a preamble sequence, a sync code and a checksum. If less than 6 bytes are in the transmit end FIFO then a packet is still sent, but idle codes replaces the unused bytes. When the transmit end FIFO is completely emptied, then the transmitter is keyed off . Figure 3: CLX2 footprint (top view) Pin description Pin 1 2 3 4 Name GND RXD TXD /TXON /RXOFF 5 VDD RSSI Function Ground Received Data output at 3V UART (inverted RS232) level Transmit Data input at 3V UART (inverted RS232) level [No pull-up] /TXON Active low Transmitter ON indicator Output [Transmit Mode] /RXOFF Active low Receiver hot Standby Input [Receive Mode] Open drain, 50kΩ internal pull-up 3.3V DC (externally regulated power supply) Received Signal Strength Indicator output (An optional pad for wire connection) RF in/out (50Ω impedance) RF Ground 1a RF 2a RFGND Notes: 1. TXD has no internal pull-up. If the unit is used in Receive only mode, tie this pin to VCC 2. VDD must be a clean 3.3V DC regulated supply 3. The STATUS pin. In transmit, this pin pulls low if the device is transmitting a data packet. On receive it floats high. If pulled low in receive, the unit goes into hot standby (<2mA) In standby the unit does not receive, but will go into transmit if valid data is presented to TXD. 4. TXD / RXD are inverted RS232 at 3V CMOS levels. To connect to a true RS232 device, inverting level shifters must be used (e.g. MAX232 type are ideal, but simple NPN transistor switches with pull-ups often suffice). With typical microcontrollers and UARTs, direct connection is possible. 5. The CLX2 provides a half duplex link, but provided no two devices attempt to transmit at one time then no further restrictions on data transmission need be made, as all transmit timing, valid data identification and datastream buffering is conducted by the unit. There is no 'transmit enable' pin. Synchronisation and framing words in the packet prevent the receiver outputting garbage in the absence of signal or presence of interference. 6. A 2.2kΩ resistance is present from RF pin 1a to ground for ESD protection Radiometrix Ltd CLX2 Data Sheet page 3 Condensed specifications Frequency Frequency stability Channel width Number of channels Supply Voltage Current Operating temperature Spurious radiations Interfaces User RF Size Transmitter Output power TX on switching time Modulation type FM peak deviation TX spurious 433.92MHz ±10kHz 400kHz 1 3.3V DC 23mA transmit 13mA receive/ <2mA standby ° ° ° ° -20 C to +55 C (Storage -30 C to +70 C) Compliant with ETSI EN 300 220-2 and EN 301 489-3 5pin 0.1" pitch molex (pin 6 absent) 2pin 0.1" pitch molex 40 x 14 x 5mm 2mW ±1dB <4ms 35kbps NRZ FSK +/-90KHz (nominal) <-36dBm Receiver Sensitivity Blocking Local Oscillator re-radiation -95dBm (for 0.1% data error) -50dB (±1MHz) <-57dBm Interface Data rate Format Levels Buffers Flow control Initial start up 19,200baud, Half duplex 1 Start bit, 8 Data bits, No parity, 1 Stop bit 3V CMOS (inverted RS232 ‘0’=0V, ‘1’=3V) 32 byte FIFO None 10ms from power on Radiometrix Ltd CLX2 Data Sheet page 4 Antenna requirements Three types of integral antenna are recommended and approved for use with the module: A) Whip This is a wire, rod ,PCB track or combination connected directly to RF pin of the module. Optimum total length is 16cm (1/4 wave @ 433MHz). Keep the open circuit (hot) end well away from metal components to prevent serious de-tuning. Whips are ground plane sensitive and will benefit from internal 1/4 wave earthed radial(s) if the product is small and plastic cased B) Helical Wire coil, connected directly to RF pin, open circuit at other end. This antenna is very efficient given it’s small size (20mm x 4mm dia.). The helical is a high Q antenna, trim the wire length or expand the coil for optimum results. The helical de-tunes badly with proximity to other conductive objects. C) Loop A loop of PCB track tuned by a fixed or variable capacitor to ground at the 'hot' end and fed from RF pin at a point 20% from the ground end. Loops have high immunity to proximity detuning. A whip *** *** * * Ultimate performance Easy of design set-up Size Immunity proximity effects B helical ** ** *** ** C loop * * ** *** The antenna choice and position directly controls the system range. Keep it clear of other metal in the system, particularly the 'hot' end. The best position by far, is sticking out the top of the product. This is often not desirable for practical/ergonomic reasons thus a compromise may need to be reached. If an internal antenna must be used, try to keep it away from other metal components, particularly large ones like transformers, batteries and PCB tracks/earth plane. The space around the antenna is as important as the antenna itself. 0.5 mm enameled copper wire close wound on 3.2 mm diameter former RF 433 MHz = 24 turns A. Helical antenna Feed point 15% to 25% of total loop length RF-GND track width = 1mm 2 C2 C3 C4 C1 4 to 10 cm inside area RF B. Loop antenna 16.4cm C. Whip antenna wire, rod, PCB-track or a combination of these three RF 433 MHz = 16.4 cm total from RF pin. Figure 4: Antenna types Radiometrix Ltd CLX2 Data Sheet page 5 Radiometrix Ltd Hartcran House 231 Kenton Lane Harrow, Middlesex HA3 8RP ENGLAND Tel: +44 (0) 20 8909 9595 Fax: +44 (0) 20 8909 2233 [email protected] www.radiometrix.com Copyright notice This product data sheet is the original work and copyrighted property of Radiometrix Ltd. Reproduction in whole or in part must give clear acknowledgement to the copyright owner. Limitation of liability The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd reserves the right to make changes or improvements in the design, specification or manufacture of its subassembly products without notice. Radiometrix Ltd does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. These radio devices may be subject to radio interference and may not function as intended if interference is present. We do NOT recommend their use for life critical applications. The Intrastat commodity code for all our modules is: 8542 6000 R&TTE Directive After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of the R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance to the essential requirements specified in Article 3 of the Directive, as appropriate to the particular equipment. Further details are available on The Office of Communications (Ofcom) web site: http://stakeholders.ofcom.org.uk/spectrum/technical/rtte/ Information Requests Ofcom Riverside House 2a Southwark Bridge Road London SE1 9HA Tel: +44 (0)20 7981 3000 Fax: +44 (0)20 7981 3333 www.ofcom.org.uk European Radiocommunications Office (ERO) Peblingehus Nansensgade 19 DK 1366 Copenhagen Tel. +45 33896300 Fax +45 33896330 [email protected] www.ero.dk