BIM2A

EW N 23 April 2007 Radiometrix Hartcran House, 231 Kenton Lane, Harrow, HA3 8RP, England Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233 BiM2A/BiM2H 433MHz Wide Band FM radio transceiver BiM2A is a half-duplex crystals controlled PLL wideband FM transceiver operating on 433.05434.79MHz European SRD band. It is an enhanced replacement for the SAW based BiM2 and has better frequency accuracy and temperature stability. BiM2H is a high power version with 25mW RF power and specifically made available for Australian/New Zealand users. Fig. 1: BiM2A-433-64 Features Data rates up to 64kbps Crystal controlled PLL FM circuitry for both Tx and Rx Receiver Sensitivity: -101dBm for 1ppm BER (64kbps) -104dBm for 1ppm BER (10kbps) Supply: 2.9V - 16V @ 14mA TX (10mW), 25mA TX (25mW), 11mA Rx Usable range up to 300 metres external, 75 metres in building SAW front end filter and full screening RSSI (standard) or carrier detect option Analogue and digital baseband Low profile with small footprint 33 x 23 x 5mm Conforms to European EN 301 489-3 and ETSI EN 300 220-3 (ERP @ 10mW) Conforms to Australian/New Zealand AS/NZS 4268:2003 (ERP @ 25mW) Instead of the SAW-based technology of the BiM2, the BiM2A and BiM2H use a PLL circuit locked to a crystal for better frequency stability over a wider temperature range (-20C to +70C) and supply range (2.9 – 16V), at the expense of slightly slower power-up. The BiM2A is available as standard on frequencies of 433.92MHz and 434.42MHz. The BiM2H can be made available if required in an extra-high-power version (BiM2EH), in the same footprint and pinout but giving 100mW nominal output power at 3.7 - 16V supply with a current consumption of less than 45mA. Applications PDAs, organisers and laptops Handheld terminals EPOS equipment, barcode scanners, belt clip printers Data loggers Audience response systems In-building environmental monitoring and control Security and fire alarms Restaurant ordering systems Vehicle data up/download Radiometrix Ltd, BiM2A Data Sheet page 1 Functional overview The transmit section of the BiM2A/H consists of a frequency modulated crystal locked PLL feeding a buffer amplifier and RF filter. A TX select line controls operation. The transmitter achieves full RF output typically within 1ms of this line being pulled low. Modulation is applied at the TXD input and may be either a serial digital stream toggling between 0V and 3V (digital drive) or a high level analogue waveform with the same peak limits (linear drive). Modulation shaping is performed internally by a 2nd order lowpass filter which minimises spectral spreading. The RF output is filtered to ensure compliance with the appropriate regulations and fed via a Tx/Rx changeover switch to the antenna pin. The receive section is a single conversion FM superhet with an IF of 10.7MHz. A SAW bandpass filter in the receiver front-end provides image rejection and suppression of other unwanted out-of-band signals. Like the transmitter, the receiver is controlled by its own active low RX select line. A post-detection lowpass filter establishes the signal bandwidth and ensures clean operation of the subsequent adaptive data slicer. The slicer is optimised for balanced data such as bi-phase code. The standard module features a received signal strength (RSSI) output with 60dB of range. A version of BiM2A featuring a fast acting Carrier Detect (CD) output on the same RSSI pin is also available. The CD output will indicate the presence of any RF signals on the carrier frequency. matching & lpf PA VCO ÷ 32 Loop Filter φ ref osc 35kHz LPF TXD Vcc 2.9 - 16V (3.7 - 16V for BiM2EH) Antenna Tx/Rx switch ÷ 32 φ Loop Filter ref osc 2.8V/3.3V Regulator & Tx/Rx logic Tx select Rx select VCO CD/ RSSI 433MHz bpf preamp IF Amp Demod LPF data slicer RXD Mixer 10.7MHz AF Pin description Fig. 2: Block diagram RF GND pins 1 & 3 RF ground pins, internally connected to the module screen and to pins 5, 9, 10 & 18 (0V). These pins should be connected directly to the RF return path (e.g. coax braid, main PCB ground plane etc). Antenna pin 2 50Ω RF connection to the antenna, DC-isolated. See pages 7 & 8 for details of suitable antennas and feeds. 0V (GND) pins 5, 9, 10 & 18 Supply ground connection and screen. RSSI pin 11 Received Signal Strength Indicator with 60dB range, operational when Rx is enabled. Output voltage nominally 0.17-0.33Vdc (no signal), 1.25Vdc (maximum). See page.6 for typical characteristics. CD pin 11 Carrier Detect - When the receiver is enabled, a low indicates a signal above the detection threshold is being received. The output is high impedance (50kΩ) and should only be used to drive a CMOS logic input. Radiometrix Ltd, BiM2A Data Sheet page 2 RXD pin 12 Digital output from internal data slicer. The output is a squared version of the signal on pin 13 (AF) and may be used to drive a decoder directly. The data is true data, i.e. as fed to the transmitter. Output is “open-collector” format with internal 10kΩ pullup to Vcc (pin 17). AF pin 13 Buffered & filtered analogue output from FM demodulator. Standing DC bias of 1V approx. Useful for test purposes or for driving external decoders. External load should be >10kΩ // 50kΩ. TX select pin 15 Active-low Transmit select. 47kΩ internal pull-up to Vcc. RX select pin 16 Active-low Receive select. 47kΩ internal pull-up to Vcc. Pin 15 TX 1 1 0 0 Pin 16 RX 1 0 1 0 Function Power down (