XE1205 XE1205 180 MHz – 1GHz Low-Power, High Link Budget Integrated UHF Transceiver GENERAL DESCRIPTION KEY PRODUCT FEATURES • Programmable RF output power: up to +15 dBm • High Rx sensitivity: down to -121 dBm at 1.2 kbit/s, -116 dBm at 4.8 kbits. • Low power: RX=14 mA; TX = 62 mA @ 15 dBm • Can accommodate 300-1000 MHz frequency range • Wide band operation: up to 304.7 kbit/s, NRZ coding • Narrow band operation: 25 kHz channels for data rates up to 4.8 kbit/s, NRZ coding; optional transmitter pre-filtering to enable adjacent channel power below -37 dBm at 25 kHz • On-chip frequency synthesizer with minimum frequency resolution of 500 Hz • Continuous phase 2-level FSK modulation • Incoming data pattern recognition • Built-in Bit-Synchronizer for incoming data and clock synchronization and recovery • FEI (Frequency Error Indicator) with built-in AFC • RSSI (Received Signal Strength Indicator) • 16-byte FIFO for transmit / receive data buffering and transfer via SPI bus The XE1205 is an integrated transceiver operating in the 433, 868 and 915 MHz license-free ISM (Industrial, Scientific and Medical) frequency bands; it can also address other frequency bands in the 180-1000 MHz range. Its highly integrated architecture allows for minimum external components while maintaining design flexibility. All major RF communication parameters are programmable and most of them can be dynamically set. The XE1205 offers the unique advantage of narrow-band and wide-band communication, this without the need to modify the number or parameters of the external components. The XE1205 is optimized for low power consumption while offering high RF output power and channelized operation suited for both the European (ETSI EN 300220-1) and the North American (FCC part 15) regulatory standards. TrueRF™ technology enables a low-cost external component count (elimination of the SAW filter) whilst still satisfying ETSI and FCC regulations. APPLICATIONS • • • • • • ORDERING INFORMATION Narrow-band and wide-band security systems Voice and data over an RF link Process and building control Access control Home automation Home appliances interconnection Part number XE1205I074TRLF (1) Rev 10 December 2008 (1) Temperature range Package -40 °C to +85 °C VQFN48 TR refers to tape & reel. LF refers to Lead Free package. This device is WEEE and RoHS compliant www.semtech.com 1 XE1205 TABLE OF CONTENTS 1 2 3 4 4.1 4.2 4.2.1 4.2.2 5 5.1 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.3 5.3.1 5.3.2 5.3.3 5.4 5.4.1 6 6.1 6.1.1 6.1.2 6.1.3 6.2 6.3 6.4 7 7.1 7.1.1 7.1.2 7.2 7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 7.2.6 7.2.7 7.2.8 7.3 7.3.1 7.3.2 7.4 7.5 7.6 7.7 8 8.1 8.2 8.3 8.4 8.5 9 Non-conformance ........................................................................................................................................................ 3 Functional Block Diagram........................................................................................................................................... 3 Pin description............................................................................................................................................................. 4 Electrical Characteristics ............................................................................................................................................ 5 Absolute Maximum Operating Ranges .......................................................................................................................... 5 Specifications................................................................................................................................................................. 5 Operating Range ........................................................................................................................................................... 5 Electrical Specifications ................................................................................................................................................. 5 Description ................................................................................................................................................................... 7 Data Operation Modes................................................................................................................................................... 7 Receiver section ............................................................................................................................................................ 8 LNA & Receiver modes ................................................................................................................................................. 8 Interrupt signal mapping ................................................................................................................................................ 8 Receiver in continuous mode......................................................................................................................................... 8 DATA pin in bidirectional or unidirectional mode (continuous mode only) ................................................................... 14 Receiver in buffered mode........................................................................................................................................... 14 Additional narrowband filter bandwidths ...................................................................................................................... 17 Transmitter section ...................................................................................................................................................... 18 Output power ............................................................................................................................................................... 18 Transmitter in continuous mode................................................................................................................................... 18 Transmitter in buffered mode....................................................................................................................................... 20 Frequency synthesizer................................................................................................................................................. 21 Clock Output for an external processor ....................................................................................................................... 21 Highest Bit RATES: example of 304.7 kbit/s operation .......................................................................................... 22 Registers settings ........................................................................................................................................................ 22 Bitrate (BR) and frequency deviation (fdev) ................................................................................................................. 22 Rx filter ........................................................................................................................................................................ 22 Tx filter......................................................................................................................................................................... 22 Hardware settings........................................................................................................................................................ 23 Operation ..................................................................................................................................................................... 23 Typical performance .................................................................................................................................................... 23 Serial interface definition and principle of operation ............................................................................................. 24 Serial Control Interface ................................................................................................................................................ 24 Chip configuration via SPI_CONFIG interface ............................................................................................................. 25 Data transmission and reception via SPI_DATA interface. .......................................................................................... 26 Configuration and status registers ............................................................................................................................... 28 Configuration register: general description .................................................................................................................. 28 MCParam configuration register (main configuration parameters)............................................................................... 29 IRQParam configuration register (IRQ parameters)..................................................................................................... 30 TXParam configuration register (transmitter configuration parameters) ...................................................................... 31 RXParam configuration register (receiver configuration parameters) .......................................................................... 31 Pattern register ............................................................................................................................................................ 33 OSCParam configuration register (oscillator parameters) ........................................................................................... 34 ADParam configuration register (additional settings)................................................................................................... 35 Operating Modes ......................................................................................................................................................... 36 XE1205 switching time using SPI_CONFIG interface.................................................................................................. 36 XE1205 switching time using SW(1:0) pins. ................................................................................................................ 38 Selection of the reference frequency ........................................................................................................................... 38 Clock output interface .................................................................................................................................................. 39 Default settings at power-up ........................................................................................................................................ 39 Pad configuration versus chip modes .......................................................................................................................... 40 Application information ............................................................................................................................................ 41 Matching network of the receiver ................................................................................................................................. 41 Matching network of the transmitter............................................................................................................................. 41 VCO tank ..................................................................................................................................................................... 44 Loop filter of the frequency synthesizer ....................................................................................................................... 45 Reference crystal for the frequency synthesizer .......................................................................................................... 46 Packaging information .............................................................................................................................................. 47 © Semtech 2008 www.semtech.com 2 XE1205 The XE1205 single-chip solution is an integrated circuit intended for use as a low cost FSK transceiver to establish a frequency-agile, half-duplex, bi-directional RF link, with non-return to zero data coding. The device is available in a VQFN 48 package and is designed to provide a fully functional multi-channel FSK transceiver. It is intended for applications in the 433 MHz and 868 MHz European bands and the North American 915 MHz ISM band. The single chip transceiver operates down to 2.4V. Its ability to operate with 25 kHz channel spacing makes it compliant with requirements of ETSI EN300 2201 and makes the XE1205 ideal for automatic meter reading and alarms. 1 NON-CONFORMANCE Please note early version lot codes whose date-codes start with N3K, N4K and N5K (except N5K3760, N5K3760A, N5K3760B and N5K6993) exhibit a non-conformance to specification. The non-conformance affects the FIFO buffer described in section 5.2.5. Please use the FIFO in this product only in conjunction with the Technical Note TN1205.01 (available www.semtech.com). All other date-codes are in conformance with the specification. IAMP VSS VSSA QAMP IAMP VDD VDDA VSSP2 VSSP VSSB VSSF VSSD VDDP VDDB VDDF FUNCTIONAL BLOCK DIAGRAM VDDD 2 IAMP IRQ_0 IRQ_1 FAMP LPF BBAMP MOSI LIM MISO MATCHING NETWORK RFA LNA DEMOD SCK BITSYNC RFB NSS_DATA FAMP LPF BBAMP LIM PATTERN MATCHING CHIP INTERFACE NSS_CONFIG SW(0) SW(1) RSSI PHASE SHIFTER LO_BUF DATA FIFO IREF FEI DIVCTL MMOD DIVIDER modulator /n Synthesizer Data shaping filter CLKXTAL XE1205 RFOUT MATCHING NETWORK PA CH PUMP PFD VCO OSCILLATOR /n CLOCK OUT IREF POR TKA VCO TANK TKB LFB XTA LOOP FILTER XTB CLKOUT TSUPP TMOD(3:0) POR XTAL Figure 1: XE1205 block diagram. © Semtech 2008 www.semtech.com 3 XE1205 3 PIN DESCRIPTION PIN 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 NAME EPAD SW(0) SW(1) NC NC RFA RFB VSSP2 VSSP2 RFOUT VDDP VSSP VDDF VSSF TKA VSSF TKB VSSF LFB VDDD VSS NSS_CONFIG NSS_DATA VDD IRQ_0 IRQ_1 DATA CLKOUT MISO MOSI SCK XTA VSSA XTB VDDA POR NC TIBIAS TSUPP VDDA VSSA QAMP IAMP TMOD(3) TMOD(2) TMOD(1) TMOD(0) NC NC I/O I/O I I O I/O I/O I/O I I O O I/O O O I I I/O I/O I/O I/O O O I/O I/O I/O I/O DESCRIPTION Pad below package (should be grounded) Transmit/Receive/Stand-by/Sleep Mode Select Transmit/Receive/Stand-by/Sleep Mode Select Not connected (should be grounded) Not connected (should be grounded) RF Input RF Input Power Amplifier Ground Power Amplifier Ground RF Output Power Amplifier Supply Voltage Power Amplifier Ground Second HF Analog Supply voltage Second HF Analog Ground VCO Tank Second HF Analog Ground VCO Tank Second HF Analog Ground PLL Loop Filter HF Digital Supply Voltage LF Digital Ground SPI SELECT CONFIG SPI SELECT DATA (DATA_IN in continuous mode) LF Digital Supply Voltage Interrupt (refer to chapter 5.2.5 for mapping options) Interrupt(refer to chapter 5.2.5 for mapping options) Data input and output (output only in continuous mode) Output clock at reference frequency divided by 2, 4, 8, 16, 32 SPI Master Input Slave Output SPI Master Output Slave Input SPI CLOCK Ref Xtal / Input of external clock LF analog ground Reference Xtal LF Analog Supply Voltage Not used (should not be connected) Not connected (should be grounded) Test pin (should be grounded in normal operation) Test pin (should be grounded in normal operation) LF Analog Supply Voltage LF analog ground Output of Q-Ch low-pass filter Output of -ChI low-pass filter Test pin (should be grounded in normal operation) Test pin (should be grounded in normal operation) Test pin (should be grounded in normal operation) Test pin (should be grounded in normal operation) Not connected (should be grounded) Not connected (should be grounded) Table 1: Pin description © Semtech 2008 www.semtech.com 4 XE1205 4 ELECTRICAL CHARACTERISTICS 4.1 ABSOLUTE MAXIMUM OPERATING RANGES Stresses above the values listed below may cause permanent device failure. Exposure to absolute maximum ratings for extended periods may affect device reliability. Symbol Description Min. Max. Unit VDDmax Supply voltage -0.5 3.9 V Tmr Storage temperature Receiver input level -55 125 5 °C ML dBm Table 2: Absolute Maximum Operation Ranges The device is ESD sensitive and should be handled with precaution. 4.2 4.2.1 SPECIFICATIONS Operating Range Symbol Description Min. Max. Unit VDDop Supply voltage 2.4 3.6 V Trop Temperature -40 85 °C Clop Load capacitance on digital ports - 25 pF Table 3: Operating Range 4.2.2 Electrical Specifications The table below gives the electrical specifications of the transceiver under the following conditions: Supply Voltage = 3.3V, temperature = 25 °C, 2-level FSK without pre-filtering, fc = 915 MHz, Δf = 5 kHz, Bit rate = 4.8 kbit/s, BWSSB = 10 kHz, BER = 0.1% (at the output of the bit synchronizer), matched impedances, environment as defined in section 8, unless otherwise specified. Symbol Description Conditions Min Typ Max Unit IDDSL Supply current in sleep mode 0.2 1 uA Quartz oscillator (39 MHz) IDDST Supply current in standby mode 0.85 1.10 mA enabled IDDR IDDT Supply current in receiver mode Supply current in transmitter mode RFOP = 5 dBm RFOP = 15 dBm - 14 33 62 16.5 40 75 mA mA mA RFS RF sensitivity Mode A Mode B - -116 -102 -113 -99 dBm dBm RFS_12 RF sensitivity at 1.2 kbit/s FDA CCR IIP3 Mode A Mode B Programmable Frequency deviation Co-channel rejection Input intercept point (from LNA input funw = fLO + 1 MHz and fLO + 1.995 MHz to base-band filter output) 1 -13 -121 -107 -10 -118 -104 255 - dBm dBm kHz dBc Mode A Mode B -37 -21 - -33 -18 10 20 - dBm dBm kHz kHz - 40 - kHz - 200 - kHz BW Base band filter bandwidth (SSB) Programmable (1) © Semtech 2008 www.semtech.com 5 XE1205 Symbol ACR_25 ACR_50 BR RFOP ACP Description Conditions Receiver adjacent channel rejection funw = fLO + 25 kHz single tone Pw=-110 dBm, mode A ratio at 25 kHz BW (SSB) = 10 kHz BW (SSB) = 8 kHz (2) Receiver adjacent channel rejection funw = fLO + 50 kHz single tone Pw=-110 dBm, mode A ratio at 50 kHz Programmable Bit rate Programmable RF output power RFOP1 RFOP2 RFOP3 RFOP4 Transmitter adjacent channel power Pre-filter enabled (RFOP3 mode) (measured at 25 kHz offset) FR Measurement conditions as defined by EN 300 220-1 V1.3.1 Programmable Synthesizer frequency range TS_SRE TS_STR TS_FS Receiver wake-up time Transmitter wake-up time Frequency synthesizer wake-up time TS_RE Receiver wake-up time TS_TR Transmitter wake-up time TS_RFSW Receiver recovery time when switching between 2 channels TS_TFSW Transmitter recovery time when switching between 2 channels TS_RSSI RSSI wake-up time TS_OS Quartz oscillator wake-up time Quartz oscillator enabled Quartz oscillator enabled Quartz oscillator enabled Frequency synthesizer enabled Frequency synthesizer enabled Between 2 channels at 1 MHz from each other Between 2 channels at 1 MHz from each other Receiver enabled Fundamental rd 3 overtone Receiver enabled Fundamental or third harmonic Exact step is XTAL / 77’824 Mode A(5), low range:VTHR1 VTHR2 VTHR3 Mode A, high range:VTHR1 VTHR2 VTHR3 TS_FEI XTAL FSTEP VTHR FEI wake-up time Quartz oscillator frequency Frequency synthesizer step Equivalent input thresholds of the RSSI SPR VIH VIL VOH VOL Spurious emission in receiver mode Digital input level high Digital input level low Digital output level high Digital output level low (3) % VDD % VDD % VDD % VDD Min Typ Max Unit - 20 30 40 - dBc dBc dBc 1.2 - 304.7(4) kbit/s -3 +2 +7 +12 - 0 +5 +10 +15 - -37 dBm dBm dBm dBm dBm 433 863 902 - 700 250 200 435 870 928 850 350 250 MHz MHz MHz us us us - 500 100 700 600 150 us us us - 150 250 us 75 75 - 1 7 2/BR 39 500 -110 -105 -100 -95 -90 -85 -65 - 1.5 2 25 25 ms ms ms ms MHz Hz dBm dBm dBm dBm dBm dBm dBm % % % % Table 4: Electrical Specifications (1) (2) (3) (4) (5) Additional bandwidths can be selected with special settings described in section 7.2.8. With additional bandwidth configuration register settings as described in sections 5.2.6 and 7.2.8. SPR strongly depends on the design of the application board and the choice of the external components. Values down to -70 dBm can be achieved with careful design. 304.7 kbit/s achievable with additional register settings as described in section 6. The 304.7kpbs max bit rate is guaranteed by validation. The max bit rate guaranteed by production test is 152.3 kbit/s RSSI also available in mode B with higher thresholds as described in section 5.2.3.4 © Semtech 2008 www.semtech.com 6 XE1205 5 DESCRIPTION The XE1205 is a direct conversion (Zero-IF) half-duplex data transceiver. It includes receiver, transmitter, frequency synthesizer and control logic. The circuit is intended primarily for operation in the following three ISM frequency bands 433 MHz, 868 MHz, and 915 MHz with a same 39MHz reference crystal and uses 2-level FSK modulation. Operation of the XE1205 over the frequency range 180 MHz - 1000 MHz beyond the ISM bands described above can be achieved by modifying the reference oscillator crystal frequency. Please contact Semtech for more details. The XE1205 is programmed by a microcontroller through the 3-wire fully-compatible SPI serial bus (MOSI, MISO, and SCK) to write to and read from the configuration registers. The circuit consists of the following main functional blocks: The receiver converts the incoming 2-level FSK modulated signal into a synchronized bit stream. The receiver comprises a low-noise amplifier, down-conversion mixers, baseband filters, baseband amplifiers, limiters, demodulator and bit synchronizer. The bit synchronizer transforms the data output of the demodulator into a glitch-free bit stream DATAOUT and synchronized clock DCLK. This may be easily used to sample the DATAOUT signal with minimal external processor overhead. In addition, the receiver includes a Received Signal Strength Indicator (RSSI) function and a Frequency Error Indicator (FEI) function that provides an indication of the local oscillator frequency error. A pattern recognition function may be used to detect a user-programmable reference word in the incoming bit stream. The bandwidth of the base-band filters, the frequency deviation of the expected incoming FSK signal as well as the bit rate of the received data signal are all user-programmable. The receiver also embeds an automatic frequency offset cancellation to compensate local oscillator drifts due to XTAL. The transmitter performs the modulation of the carrier by an input baseband data signal and the transmission of the modulated signal. The frequency synthesizer is modulated directly. The modulated signal is then amplified by the on-chip RF power amplifier. The output power is user-programmable to one of four possible values. The frequency deviation and the bit rate for the transmit signal are the same as those programmed for the receiver section. User-defined pre-filtering should be enabled to ensure compliance with the requirements of ETSI EN 300 220-1 regarding transmission at 25 kHz channel spacing. The frequency synthesizer generates the local oscillator (LO) signal for the receiver section as well as the FSK modulated signal for the transmitter section. The core of the synthesizer is implemented with a PLL structure. The frequency is user-programmable with a frequency resolution of approximately 500 Hz in the 433 MHz, 868 MHz and 915 MHz ISM frequency bands. This section includes a crystal oscillator whose signal is the reference for the PLL. This reference frequency is divided by 2, 4, 8, 16, or 32 and is made available at the CLKOUT pin to serve as a clock signal for an external processor. The control block generates the control signals according to the setting in its set of configuration registers. The service block performs all the necessary functions for the circuit to work properly, including the internal voltage and current sources. 5.1 DATA OPERATION MODES The XE1205 is user-programmable between two modes of operation: Continuous mode: each bit transmitted or received is accessed directly at the DATA input/output pin. Buffered mode: a 16-byte FIFO is used to store each data byte transmitted or received. This data is written to/read from the FIFO via the SPI bus. It reduces processor overhead. © Semtech 2008 www.semtech.com 7 XE1205 5.2 RECEIVER SECTION The XE1205 is set to receive mode when MCParam_Select_mode is low by setting MCParam_Chip_mode(1:0) to “01”. If MCParam_Select_mode is high the XE1205 is set to receive mode by setting SW(1:0) to “01”. 5.2.1 LNA & Receiver modes The LNA of the receiver has two programmable operation modes: the high sensitivity mode, Mode A, for reception of weak signals; and the high linearity mode, Mode B, for strong signals. The operation mode is defined by the value of the Rmode bit in RXParam_Rmode configuration register. Mode A: High sensitivity mode, RFS approximately 13dB better than in Mode B (see 4.2.2, RFS parameter) Mode B: High Linearity mode, IIP3 approximately 15dB higher than in Mode A (see 4.2.2, IIP3 parameter) 5.2.2 Interrupt signal mapping In receiver mode, two lines are dedicated to interrupt information. The interrupt pins are IRQ_0 and IRQ_1. IRQ_0 has 3 selectable sources. IRQ_1 has 2 selectable sources. The two following tables summarize the interrupt management. IRQParam_RX_irq_0 00 01 10 11 00 01 10 11 MCParam_Buffered_mode 0 0 0 0 1 1 1 1 IRQ_0 Output Output Output Output Output Output Output Output IRQ_0 Interrupt source Pattern RSSI_irq Pattern Pattern No interrupt available Write_byte /fifoempty Pattern Table 5: IRQ_0 interrupt sources in receive mode. IRQParam_RX_irq_1 00 01 10 11 00 01 10 11 MCParam_Buffered_mode 0 0 0 0 1 1 1 1 IRQ_1 Output Output Output Output Output Output Output Output IRQ_1 Interrupt source DCLK DCLK DCLK DCLK No interrupt available Fifofull RSSI_irq RSSI_irq Table 6: IRQ_1 interrupt sources in receive mode. 5.2.3 Receiver in continuous mode In this mode, the receiver has two output signals indicating recovered clock DCLK and recovered NRZ bit DATA. DCLK is connected to output pin IRQ_1 and DATA is connected to pin DATA configured in output mode. The bit synchronizer controls the recovered clock signal, DCLK. If the bit synchronizer is enabled by setting the bit /RXParam_Disable_bitsync to “0” (default value), the clock recovered from the incoming data stream appears at DCLK. The function of the bit synchronizer is to remove glitches from the data stream and to provide a synchronous clock at DCLK. The output DATA is valid at the rising edge of DCLK. The following diagram shows the receiver chain operating in this mode © Semtech 2008 www.semtech.com 8 XE1205 If the bit synchronizer is disabled, the DCLK output is held low and the raw demodulator output appears at DATA. . RXParam_Disable_bitsync 1 I_lim Q_lim data FSK DEMODULATOR DATA 0 BIT SYNCHRONIZER data IRQ_1(DCLK) dclk RXParam_Pattern IRQParam_Rx_irq_0(1:0) PATTERN MATCHING RXParam_RSSI pattern IRQ_0 RSSI RSSI_irq Figure 2: Receiver chain in continuous mode 5.2.3.1 Demodulator in continuous mode The demodulator section comprises FSK demodulator, bit synchronizer, and Pattern Recognition blocks. Data from the FSK baseband limited signals I_lim and Q_lim is first demodulated before passing to the bit synchronizer. If the end-user application requires direct access to the output of the demodulator, then the RXParam_Disable_bitsync bit must be set high. In this case the demodulator output is directly connected to the DATA pin and the IRQ_1 pin (DCLK) is set to low. For best operation of the demodulator it is recommended the modulation index β of the input signal meets the following condition: β = 2 Δf BR ≥2 where Δf is the frequency deviation and BR the bit rate. © Semtech 2008 www.semtech.com 9 XE1205 5.2.3.2 Bit synchronizer in continuous mode The raw output signal from the demodulator may contain jitter and glitches. The bit synchronizer converts the data output of the demodulator into a glitch-free bit-stream DATA and generates a synchronized clock DCLK to be used for sampling the DATA output (see below). DCLK is available on pin IRQ_1 when the chip operates in continuous mode. DATA (NRZ) DCLK Figure 3: Bit synchronizer timing diagram For proper operation, in addition to the requirement for the modulation index defined in Section 5.2.3.1, the Bit Synchronizer must first receive three bytes of alternating logic value preamble, i.e. “0101” sequences. After this startup phase, the rising edge of DCLK signal is centered on the demodulated bit. Subsequent data transitions will preserve this centering. This has two implications: • If the Bit Rates of Transmitter and Receiver are known to be the same, the XE1203F will be able to receive an infinite unbalanced sequence (all “0s” or all ”1s”) with no restriction. • If there is a difference in Bit Rate between Tx and Rx, the amount of adjacent bits at the same level that the BitSync can withstand can be estimated as: Number of bits = 0.5⋅ BR ΔBR This implies approximately 6 consecutive unbalanced bytes when the Bit Rate precision is 1%, which is easily achievable (crystal tolerance is in the range of 50 to 100 ppm). It is recommended that the bit rate accuracy be better than ±5% (3% for Konnex mode operation). The bit synchronizer is enabled by default. It is controlled by RXParam_Disable_bitsync. If the bit synchronizer is disabled the output of the demodulator is directed to DATA and the DCLK output (IRQ_1 Pin in continuous mode) is set to ‘0’. The received bit rate is defined by the value of the MCParam_Br(6:0) configuration register, and is calculated as follows: Bit rate = 152.34e3 where int(x) is the integer value of the unsigned binary representation of x. int(Br(6 : 0)) + 1 For the Konnex standard operation, the bit rate is fixed at 32.768 kbit/s. The bit synchronizer is automatically configured with the right bit rate value if the MCParam_Knx configuration bit is set high. If needed, it is possible to select intermediate bit rates by changing the Over-Sampling Ratio (OSR) of the bit synchronizer, whose default value is 32. The latter can be superseded by setting high the register TParam_Chg_OSR. In this case, the bit rate becomes: Bit rate = 152.34e3 32 , ⋅ int(Br(6 : 0)) + 1 int(OSR(7 : 0)) + 1 © Semtech 2008 www.semtech.com 10 XE1205 where OSR(7:0) is the content of the register; TParam_OSR(7:0) as described in section 7.2.8. For a correct operation of the bit synchronizer, the value of this register must be higher or equal to 15 and (int(OSR)+1) * Bit_rate should be inferior or equal to 4.87MHz. 5.2.3.3 Pattern recognition block in continuous mode In receive mode this feature is activated by setting the RXParam_Pattern configuration register bit to high. The demodulated signal is compared with a pattern stored in the Reg_pattern(31:0) registers. The PATTERN signal (mapped to output pin IRQ_0) is driven by the output of this comparator and is synchronized by DCLK. It is set to high when a matching condition is detected, otherwise set to low. PATTERN output is updated at the rising edge of DCLK. The number of bits used for comparison is defined in the RXParam_Psize(1:0) register and the number of tolerated errors for the pattern recognition is defined in the RXParam_Ptol(1:0) register. Figure 4, illustrates the pattern matching process. DATA (NRZ) Bit N-x = Reg_pattern[x] Bit N-1 = Reg_pattern[1] Bit N = Reg_pattern[0] DCLK PATTERN Figure 4: Pattern matching operation. Note: The pattern recognizer is available only if the bit synchronizer is enabled. 5.2.3.4 RSSI in continuous mode This function provides a Received Signal Strength Indication based on the signal level at the output of the base-band filter. To activate this function, the bit RXParam_RSSI must be set to “1”. When activated, the 2-bit status information is stored in register RXParam_RSSI_OUT(1:0) and may be read through the serial control interface. The meaning of this status information is given in the table below, where VRFFIL is the differential amplitude of the equivalent input RF signal when the receiver is operated in mode A. The thresholds VTHRi are at the output of the base-band filter divided by the gain between the input of the receiver and this output. When operated in mode B, equivalent VTHRi thresholds are shifted 15dBm higher. RXPARAM_RSSI_out(1:0) 00 Description VRFFIL ≤ VTHR1 01 VTHR1 < VRFFIL ≤ VTHR2 10 VTHR2 < VRFFIL ≤ VTHR3 11 VTHR3 < VRFFIL Table 7: RSSI status description The operating range of the RSSI measurement may be changed by programming the RXParam_RSSI_range bit; in this way two ranges with three VTHRi values may be selected. An additional way to increase RSSI operating range is to combine modes A and B thresholds. One could then cover input signals ranging from -110dBm (VTHR1, low range, mode A) up to -70dBm (VTHR3, high range, mode B) © Semtech 2008 www.semtech.com 11 XE1205 The time diagram of an RSSI measurement is given in Figure 5. When the RSSI function has been activated the signal strength is periodically measured and the result is stored in RSSI_out_int; this result is transferred to the register RXParam_RSSI_out(1:0) each time this register is read via the SPI interface. TS_RSSI is the wake-up time required after the function has been activated to get a valid result and its value is given in section 4.2.2. TS_RSSIM is the period between two successive measurements and its value depends on the selected frequency deviation (100 μs for Δf > 20 kHz, 200 μs for 10 kHz < Δf ≤ 20 kHz, 300 μs for 7 kHz < Δf ≤ 10 kHz, 400 μs for 5 kHz < Δf ≤ 7 kHz, and 500 μs Δf ≤ 5 kHz). RXParam_RSSI Read RSSI NSS_CONFIG TS_RSSI RSSI_out_int Read RSSI TS_RSSIM val1 xxx val2 val3 val4 0 saout_rssi RXParam_RSSI_out xxx val1 val4 Figure 5: RSSI measurement timing diagram Saout_rssi is internally generated during a read sequence of RXParam_RSSI_out register. The RSSI block can also be used in interrupt mode by setting the bit IRQParam_RSSI_int to 1. When RSSI_out_int is equal or greater than a predefined value stored in IRQParam_RSSI_thr(1:0), the signal IRQParam_RSSI_signal_detect (can be read in the Configuration register) goes high and an interrupt signal RSSI_irq is generated. This interrupt signal can be used by a microcontroller if IRQParam_RX_irq_0 is set to “01” (see table 5).The interrupt is cleared by writing a 1 to the bit IRQParam_RSSI_signal_detect. If the bit IRQParam_RSSI_int remains high, the process starts again. The next figure shows the timing diagram of RSSI in interrupt mode. IRQParam_RSSI_int RSSI_out_int 00 00 00 10 10 00 00 00 00 00 11 10 00 10 10 11 00 IRQParam_RSSI_signal_detect IRQParam_RSSI_thr = “10” Clear interrupt RSSI_irq Figure 6: RSSI generating interrupt signal when detecting a threshold © Semtech 2008 www.semtech.com 12 XE1205 5.2.3.5 Frequency Error Indicator in continuous mode – FEI The block is switched ON by writing bit RXParam_FEI to ‘1’.This function provides information about the frequency error of the local oscillator compared with the input carrier frequency and can be used to implement an external AFC. The condition on the modulation index for proper behavior of the FEI function is: β= 2 ⋅ Δf BR ≥ 2, Where Δf is the frequency deviation and BR is the bit rate. The time diagram of an FEI measurement is given in the next figure. When the FEI block has been woken up and is ready, and as long as the block is kept on, the frequency error is measured and the current result of the measurement is loaded in the register RXParam_FEI_out(15:0) each time registers 12 is read. TS_FEI is the time required for the first evaluation to be completed after the block has been started up and its value is given in section 4.2.2. Since the contents of the configuration register is validated at the rising edge of the enable signal NSS_CONFIG, the FEI block is actually started up at this time. RXParam_FEI Read RSSI NSS_CONFIG fei_out_int TS_FEI TS_FEI XXX Read RSSI val1 val2 val3 val4 val5 val6 0 saout_fei RXParam_FEI_out val2 0 val5 Figure 7: Timing diagram of an FEI measurement To guarantee proper behavior of the FEI, the operation must be done when a preamble as defined in section 5.2.3.1 is received, and the sum of the frequency offset and the signal bandwidth (single sided) must be lower than the base band filter bandwidth (single sided). That is: Foffset + SignalBW < FilterBW. Where foffset is the difference between the carrier frequency and the LO frequency, SignalBW is the signal bandwidth (single side) equal to the sum of the bit rate divided by 2 and the frequency deviation (BR/2 + DF), and FilterBW is the channel filter bandwidth defined by RXParam_BW(1:0) parameters. The frequency error can be calculated by the following formula: The frequency error = 500*int(FEI_out(15:0)) in Hz Where int(x) is the integer value of the signed binary representation of x. © Semtech 2008 www.semtech.com 13 XE1205 5.2.3.6 Frequency Error Correction XE1205 offers two possibilities to correct the RF frequency error either by using FEI block with external microcontroller setting the corrected LO_Frequency or by using the internal Automatic Frequency error Cancellation (AFC). When using FEI block, RXParam_FEI_out(15:0) can directly be subtracted to the register MCParam_Freq_lo(15:0) without further calculation by a microcontroller since the PLL step is 500 Hz i.e. RXParam_FEI_out (15:0) represents the number of step needed to compensate the frequency error . Saout_fei is internally generated during a read sequence of register 12 in the same way as saout_rssi (refer to Figure 7). To use AFC block, FEI block should be switched on by writing bit RXParam_FEI to ‘1’ then AFC should be started by writing bit RX_Param:AFC_start to ‘1’. The LO_frequency error cancellation is effective providing bit RXParam_disable is written to ‘0’ .Refer to previous chapter to guarantee proper behaviour of the FEI. RXParam_AFC_OK status register is automatically set to ‘0’ when AFC is completed. RXParam_AFC_overflow will be automatically set to ‘1’ in case the frequency error is too high to be automatically cancelled. 5.2.4 DATA pin in bidirectional or unidirectional mode (continuous mode only) The DATA pin is bi-directional by default, and is used in both transmit and receive modes. In receive mode, DATA represents demodulated received data. In transmit mode baseband data is applied to this pin. Some applications may require a separate input and output for transmitted and received data respectively. In this case the MCParam_Data_unidir configuration register bit must be set to ‘1’. The DATA pin is then set permanently to an output for received data, and NSS_DATA is used as the input. 5.2.5 Receiver in buffered mode In this mode, the output of the bit synchronizer, i.e. the demodulated and resynchronized signal and the clock signal DCLK are not sent directly to the output pins DATA and IRQ_1 (DCLK). These signals are used to store the demodulated signal by packet of 8 bits in a 16 bytes FIFO. The following figure shows the receiver chain in this mode. The FSK demodulator, bit synchronizer and pattern matching block work as described in section 5.2.2 but they are used with two additional blocks, FIFO and SPI. When the chip is in receive mode and the MCParam_Buffered_mode bit is set to high then all the blocks described above are automatically enabled. In a normal communication frame the data stream comprises a 24 bit preamble, pattern (refer to section 5.2.3.3) and the data. Upon receipt of a recognized pattern, the receiver recognizes the start of a frame, strips off the preamble and pattern, then fills the FIFO with payload data to the microcontroller. This automated data recovery reduces the overhead for the host controller. The IRQParam_Start_fill bit determines how the FIFO is filled: If IRQParam_Start_fill is low, data only fills the FIFO subject to a correct pattern match. Data is shifted into the pattern recognition block which continuously compares the received data with the contents of the Reg_pattern(31:0) configuration register. If a match occurs a start sequence is detected, and the internal output of the pattern matching block is asserted for one bit length and the IRQParam_Start_detect bit is also asserted. This internal signal may be mapped to the IRQ_0 output using interrupt signal mapping (please refer to section 5.2.2). Once a pattern match has occurred, the pattern recognition block will remain inactive until IRQParam_Start_detect is re-asserted. © Semtech 2008 www.semtech.com 14 XE1205 /RXParam_Disable_bitsync = ‘0’ Q_lim FSK I_lim DEMODULATOR BIT SYNCHRONIZER RXParam_Pattern = ‘1’ PATTERN MATCHING data dclk Shift reg Fifowrite byte 8 pattern write_byte IRQ_0 /fifoempty FIFO RXParam_RSSI Fifofull IRQ_1 8 Fiforead RSSI_irq Load_spi RSSI Fifoout SPI DATA regspidata MOSI MISO SCK NSS_DATA . Figure 8: Receiver chain in buffered mode If IRQParam_Start_fill is high, FIFO filling is initiated by asserting IRQParam_Start_detect. Once sixteen bytes have been written to the FIFO the IRQParam_Fifofull signal is asserted. Data should then normally be read out. If no action is taken the FIFO will overflow and subsequent data will be lost. If this occurs the IRQParam_Fifooverrun bit is set. The IRQParam_Fifofull signal can be mapped to pin IRQ_1 as an interrupt for a microcontroller if IRQParam_RX_irq_1 is set to “01” (please refer to section 5.2.2). To recover from an overflow situation a ‘1’ must be written to IRQParam_Fifooverrun; this clears the contents of the FIFO, resets all FIFO status flags and re-initiates pattern matching (only when an overrun has occurred). In order to clear the FIFO in reception, a “1” should be written in IRQParam_start_detect (bit 6 add 6). Pattern matching can also be re-initiated during a FIFO filling sequence by writing a ‘1’ to IRQParam_Start_detect. © Semtech 2008 www.semtech.com 15 XE1205 data “noisy” data preamble c pattern b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13 b14 b15 b16 pattern /fifoempty fifofull Fifooverrun (flag) write_byte FIFO 15 0 b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12 b13 b14 b15 Figure 9: Start detection and FIFO filling The FIFO filling process is shown in detail in Figure 9. As the first byte is written into the FIFO the signal /fifoempty goes high indicating that at least one byte is present. The microcontroller can then read the contents of the FIFO via the SPI interface. Once all data have been read from the FIFO then /fifoempty goes low. Once the last bit of the sixteenth byte has been written into the FIFO then the signal Fifofull is asserted; data should be read before the next byte is received. This is illustrated in Figure 10. Completion of FIFO filling DCLK DATA Byte 14 Byte 15 Byte 16 Byte 17 PATTERN Write_byte /Fifoempty Fifofull IRQParam_Fifooverrun Figure 10: Completion of FIFO filling The /fifoempty signal can be used as an interrupt signal for a microcontroller by mapping to pin IRQ_0 if IRQParam_RX_irq_0 is set to “10” (please refer to section 5.2.2). Alternatively, the WRITE_BYTE signal may also be used as an interrupt if IRQParam_RX_irq_0 is set to “01”. 5.2.5.1 Demodulator in buffered mode Demodulation in buffered mode occurs in the same way as in continuous mode (section 5.2.3.1). Received data is directly read from the FIFO and the DATA pin is not used. © Semtech 2008 www.semtech.com 16 XE1205 5.2.5.2 Bit synchronizer in buffered mode In buffered mode the bit synchronizer is automatically enabled (DCLK is not externally available). 5.2.5.3 Pattern recognition block in buffered mode In buffered mode the pattern recognition block is automatically enabled. The PATTERN signal may be mapped to pin IRQ_0. Please refer to section 5.2.2 for further details. 5.2.5.4 RSSI in buffered mode In buffered mode the Received Signal Strength Indication operates the same way as in continuous mode. In buffered mode, however, RSSI_irq may be mapped to IRQ_1 (please refer to section 5.2.2) instead of to IRQ_0 in continuous mode. 5.2.5.5 Frequency Error Indicator in buffered mode – FEI In buffered mode the Frequency Error Indication operates the same way as in continuous mode. Please refer to section 5.2.3.5 for more details. 5.2.6 Additional narrowband filter bandwidths The lowest bandwidth for the base-band filter which can be selected by changing only a 2-bit word in the configuration register is 10 kHz. However, as described in section 7.2.8, additional register settings allow this bandwidth to be further reduced. This option allows the user to improve the selectivity of the receiver for very narrow-band applications. Activating this option is advised for bit rates and frequency deviations not higher than 4.8 kbit/s and 5 kHz and if the LO frequency of the receiver is well controlled, for instance by means of a very accurate crystal or the activation of an AFC. The table below gives the sensitivity and the adjacent channel rejection for BR = 4.8 kbit/s and Δf = 5 kHz for different bandwidths. Bandwidth TParam_Low _BW TParam_Code_BW(8:0) SSB 10 kHz 0 X Sensitivity RFS (BER=0.1%) Adjacent Channel Rejection ACR (25 kHz offset single tone) -116 dBm 20 dBc 9 kHz 1 139 -116 dBm 25 dBc 8 kHz 1 160 -115.5 dBm 30 dBc 7 kHz 1 185 -115 dBm 35 dBc Table 8: Performances of the receiver for very narrow bandwidths and 4.8 kbit/s Table 9 below gives the sensitivity and the adjacent channel rejection for BR = 1.2 kbit/s and Δf = 2 kHz. Bandwidth SSB TParam_Low _BW TParam_Code_BW(8:0) Sensitivity RFS (BER=0.1%) Adjacent Channel Rejection ACR (25 kHz offset single tone) 10 kHz 0 X -117.5 dBm 18 dBc 9 kHz 1 139 -118 dBm 23 dBc 8 kHz 1 160 -119 dBm 28 dBc 7 kHz 1 185 -119.5 dBm 33 dBc Table 9: Performances of the receiver for very narrow bandwidths and 1.2 kbit/s It can be seen from table 9 that this option also allows the sensitivity to be improved for very low bit rates and frequency deviations. © Semtech 2008 www.semtech.com 17 XE1205 5.3 TRANSMITTER SECTION The XE1205 is set to transmit mode when MCParam_Select_mode is low by setting MCParam_Chip_mode(1:0) to “10”. If MCParam_Select_mode is high the XE1205 is set to transmit mode by setting pins SW(1:0) to “10”. The data directly modulates the LO, or an (optional) pulse shaping filter can be used resulting in an adjacent channel power down to -37dBm at 25kHz for an output power up to 10dBm. In continuous mode the transmitted data is sent directly to the frequency synthesizer. In buffered mode the data is first written into the sixteen byte FIFO via the SPI interface; data from the FIFO is used to modulate the frequency synthesizer. 5.3.1 Output power The output power of the power amplifier is programmable on four values with the register TXParam_Power (please refer to section 7.2.4 below), as shown in Table 10, where RFOP values are given in the Electrical Specifications section 4.2.2. TXParam_POWER 00 Output power RFOP1 01 RFOP2 10 RFOP3 11 RFOP4 Table 10: Output power settings 5.3.2 Transmitter in continuous mode The transmitter works in continuous mode if the bit MCParam_Buffered_mode is low. The transmit data should be applied to pin DATA if register bit Data_unidir is low or pin NSS_DATA if register bit Data_unidir is high. Figure 11 shows the transmitter chain in continuous mode: MCParam_Data_unidir 0 modulator 1 0 Data shaping filter datain TXParam_Filter DATA NSS_DATA 1 IRQ_1 Figure 11: Transmitter data path in continuous mode The pulse shaping function is enabled by setting TXParam_Filter to ‘1’. If the filtering option is selected, the DCLK signal is used as data clock in the transmission and this clock is generated at a frequency according to the selected bit rate. The DCLK signal is supplied to the microcontroller via the pin IRQ_1 which must update the data on the falling edge. The data is sampled at the rising edge of DCLK and filtered. Figure 12 shows an example of filtered data for a bit rate of 4.8kbit/s and a frequency deviation of 5 kHz: © Semtech 2008 www.semtech.com 18 XE1205 Figure 12: Pre-filtering of bit stream in transmit mode The filtering option can be used for all bit rates specified in section 5.2.3.2 and for the following frequency deviations. Freq_dev(8:0) Frequency deviation (kHz) 000000101 2.5 000001010 5 000010100 10 000101000 20 001010000 40 010100000 80 101000000 160 Table 11: Available frequency deviations when using the filtering option © Semtech 2008 www.semtech.com 19 XE1205 5.3.3 Transmitter in buffered mode. The transmitter works in buffered mode if bit MCParam_Buffered_mode is high. Data to be transmitted is written to the 16-byte FIFO via the SPI interface. The data is loaded into a shift register which passes the data bit by bit to the data shaping filter or directly to the frequency synthesizer (as explained in the previous section). The transmitter chain is shown in Figure 13: IRQ_0 0 modulator Data shaping filter 1 shift register dclk /fifoempty FIFO TXParam_Filter IRQ_1 SPI MOSI MISO SCK NSS_DATA Figure 13: Transmit chain in buffered mode FIFO operation in transmit mode is similar to receive mode; transmission either starts immediately after data is written into the FIFO or when the FIFO is full, determined by the IRQParam_Start_full bit setting. If the transmit FIFO is full the interrupt signal fifofull is asserted on pin IRQ_1 (if configured accordingly). If data is written into the FIFO while it is full, the flag IRQParam_Fifooverrun will be set to ‘1’ and the previous FIFO contents will be overwritten. The IRQParam_Fifooverrun flag is cleared by writing a ‘1’ to it. At the same time this clears the contents of the FIFO. Once the last data in the FIFO is loaded into the shift register, the flag /fifoempty is set to high on pin IRQ_0. If new data is not written in the FIFO and the last bit of the shift register has been transferred to the frequency synthesizer, the bit IRQParam_Tx_stopped goes high and the data seen by the frequency synthesizer is the last bit sent. If the transmitter is switched off (e.g. entry into another mode), the transmission will stop immediately even if there is still unsent data in the shift register. In transmit mode the two interrupt signals are IRQ_0 and IRQ_1. IRQ_1 is mapped to IRQParam_Fifofull signal indicating that the transmission FIFO is full when IRQParam_Tx_irq_1 is set to ‘0’ and to TX_stopped when IRQParam_Tx_irq_1 is set to ‘1’. IRQ_0 is mapped to the /fifoempty signal; this signal is used to indicate that the transmission FIFO is empty and must be refilled with data to continue data transmission. © Semtech 2008 www.semtech.com 20 XE1205 5.4 FREQUENCY SYNTHESIZER The Frequency Synthesizer generates the local oscillator (LO) signal for the receiver section as well as the continuous phase FSK (CPFSK) modulated signal for the transmitter section. The core of the synthesizer is implemented with a Sigma-Delta PLL architecture. The frequency is programmable with a step-size of 500 Hz in the 433, 868 and 915 MHz frequency bands. This block includes a crystal oscillator which provides the frequency reference for the PLL. This reference frequency can also be used as a reference clock for the external microcontroller on the CLKOUT pin. 5.4.1 Clock Output for an external processor A reference clock can be generated for use by an external microcontroller. The OSCParam_Clkout configuration bit controls the CLKOUT pin. When set to high, CLKOUT is enabled, otherwise it is disabled. The output frequency at CLKOUT is defined by the value of the OSCParam_Clkout_freq(2:0) parameter. The output frequency at CLKOUT is the reference oscillator frequency divided by 2, 4, 8, 16 or 32. With a reference oscillator frequency of 39 MHz this provides a reference clock at 19.5 MHz, 9.75 MHz, 4.87 MHz, 2.44 MHz or 1.22 MHz, respectively. This clock signal is disabled in Sleep Mode. © Semtech 2008 www.semtech.com 21 XE1205 6 HIGHEST BIT RATES: EXAMPLE OF 304.7 KBIT/S OPERATION XE1205 is able to sustain other bit rates between 152.34 kbit/s and 304.7 kbit/s using OSR_minus_1 register as described in section 5.2.3.2. It is recommended whenever possible to use a modulation index (β=2Δf/BR) ≥2 whenever possible. For the highest bit rates the receiver filter bandwidth will limit the maximal usuable β. Lower modulation indexes should be used then. In this chapter we provide the example of the highest bit rate. In order to operate at 304.7 kbit/s the following settings should be used: Please note that exact bitrate value is 304.6875 kbit/s. 6.1 REGISTERS SETTINGS 6.1.1 Bitrate (BR) and frequency deviation (fdev) At 304.7 kbit/s, a modulation index close to 1 is compulsory because of the limited bandwidth of the Rx filter. Frequency deviation will be set to 160 kHz to also take benefit from the Tx filter available (Cf Table 11). Consequently, following settings should be programmed: Name Address 0 1 2 27 28 Freq_dev(8:0) Br(6:0) Chg_OSR OSR (7:0) Bits 0 7-0 6-0 4 7-0 Value (d) Note 320 160.36 kHz 0 1 15 152.34 kbit/s… …=>304.68 kbit/s Table 12: common registers settings for 304.7 kbit/s 6.1.2 Rx filter For a correct behavior we recommend to have an Rx filter bandwidth of minimum fdev + (BR/2). Consequently, following settings should be programmed: Name BW(1:0) Max_BW TParam_Low_BW TParam_Code_BW(8:0) Address 8 8 19 21 22 Bits 6-5 4 2 6-0 7-6 Value (d) 3 0 1 Note 200 kHz… 87 …=>320 kHz Table 13: Rx registers settings for 304.7 kbit/s 6.1.3 Tx filter Tx filter is also available at 304.7 kbit/s operation and although not compulsory, its use is recommended to reduce spectrum bandwidth. Contrary to the other bitrates, an additional specific bit must be set. Consequently, following settings should be programmed: Name Filter 304 kbit/s_filter Address 7 18 Bits 4 3 Value (d) 1 1 Note Table 14: Tx registers settings for 304.7 kbit/s © Semtech 2008 www.semtech.com 22 XE1205 6.2 HARDWARE SETTINGS When operating at 304.7 kbit/s, the loop filter must be modified. Typical recommended component values are provided below : Name 434 MHz 869 MHz 915 MHz Tolerance CL1 3.3 nF 10 nF 10 nF ± 5% CL2 220 pF 150 pF 150 pF ± 5% RL1 1.5 kΩ 1.5 kΩ 1.5 kΩ ± 5% Table 15: PLL Loop Filter Bill of Material for 304.7 kbit/s 6.3 OPERATION Like for any other configuration, in order to avoid crystal misalignment issues and get the best performance it is recommended to perform an AFC with maximum Rx filter bandwidth before using the 304.7 kbit/s with the settings described above. AFC operation may need to be performed at a lower datarate to cover worst case crystal, process and temperature variations. Please note that all features including FIFO are available at bit rates up to 304.7 kbit/s. 6.4 • • TYPICAL PERFORMANCE [email protected]%: -102 dBm in mode A and -90 dBm in mode B. ACR@1MHz offset, single tone: 25 dBc. © Semtech 2008 www.semtech.com 23 XE1205 7 SERIAL INTERFACE DEFINITION AND PRINCIPLE OF OPERATION 7.1 SERIAL CONTROL INTERFACE The XE1205 contains two SPI-compatible serial interfaces, one to send and read the chip configuration, the other to send and receive data in buffered mode. Both interfaces are configured in slave mode and share the same pins MISO (Master In Slave Out), MOSI (Master Out Slave In), SCK (Serial Clock). Two additional pins are required to select the SPI interface: NSS_CONFIG to change or read the transceiver configuration, and NSS_DATA to send or read data. SW(1) SW(0) Figure 14 shows the connections between the transceiver and a microcontroller when buffered mode is used. IRQ_0 and IRQ_1 are not mentioned in the drawing but can be used. SPI CONFIG (slave) NSS_CONFIG MOSI MISO SCK XE1205 CORE NSS_CONFIG MOSI MISO SCK NSS_DATA µC SPI DATA (slave) (master) NSS_DATA XE1205 Figure 14: Connection between SPI DATA, SPI CONFIG and a micro-controller It is possible to change between the four modes (sleep, stand-by, receive, transmit) by using the two-bit signal SW(1:0). This option is enabled by setting the bit MCParam_Select_mode to ‘1’ in the configuration register. A byte transmission can be seen as a rotate operation between the value stored in an 8 bit shift register of the master device (the microcontroller for instance) and the value stored in an 8 bit shift register of the selected slave device (the transceiver). The SCK line is used to synchronize both SPI interfaces. Data is transferred full-duplex from master to slave through the MOSI line and from slave to master through the MISO line. The most significant bit is always sent first. In both SPI interfaces the rising SCK edge is used to sample the received bit, and the falling SCK edge shifts the data inside the shift register. Max SCK frequency is 2MHz. The NSS_CONFIG or NSS_DATA signal is controlled by the master device and should remain low during the byte transmission. It is not necessary to toggle the NSS_CONFIG signal back to high and back to low between each transmitted byte. However It is necessary to toggle the NSS_DATA signal back to high and back to low between each transmitted byte. The transmission is synchronized by the NSS_CONFIG or NSS_DATA signal. While the NSS_CONFIG or NSS_DATA is high, the counters controlling transmission are reset. Reception starts with the first clock cycle after the falling edge of NSS_CONFIG or NSS_DATA; if either signal goes high during a byte transmission the counters are reset and the byte has to be retransmitted. © Semtech 2008 www.semtech.com 24 XE1205 7.1.1 Chip configuration via SPI_CONFIG interface The SPI_CONFIG interface is selected if NSS_CONFIG is low even if the circuit is in buffered mode and NSS_DATA is low (SPI_CONFIG has priority). To configure the transceiver two bytes are required; the first byte contains a start bit (equal to 0), R/W information (‘1’ for a read operation or ‘0’ for a write operation), 5 bits for the address of the register and finally a stop bit (equal to ‘1’). The second byte contains the data to be sent in write mode or the new address to read from in read mode. Figure 15 shows the timing diagram for a typical write sequence: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 SCK New value of register A1* MOSI start rw A(4) A(3) A(2) A(1) A(0) stop D(7) D(6) D(5) D(4) D(3) D(2) D(1) D(0) Data at address A1* Address = A1 MISO HZ x x x x x x x x D(7) D(6) D(5) D(4) D(3) D(2) D(1) D(0) HZ sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift Sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift NSS_CONFIG * when writing the new data at address A1, the previous contents of A1 can be read by the micro-controller Figure 15: Write sequence when sending a new configuration to the XE1205 via the SPI _CONFIG NSS_CONFIG must remain low during the transmission of the two bytes (address and data); if it goes high after the first byte, then the next byte will be considered as an address byte. When writing more than one register successively, NSS_CONFIG does not need to make a high to low transmission between two write sequences. The bytes are alternatively considered as an address byte followed by a data byte. The read sequence via the SPI_CONFIG interface is similar to the write one except that the data byte contains all zeroes © Semtech 2008 www.semtech.com 25 XE1205 Figure 16 shows the read sequence of a single register: 1 2 3 start rw A(4) X X X 4 5 6 7 8 9 10 11 12 13 14 15 16 SCK MOSI MISO HZ A(3) A(2) A(1) A(0) stop X X X X X D(7) D(6) D(5) D(4) D(3) D(2) D(1) D(0) HZ sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift sample shift NSS_CONFIG Figure 16: Read sequence of a single register via the SPI _CONFIG 7.1.2 Data transmission and reception via SPI_DATA interface. When the transceiver is used in buffered mode, the data exchange with a micro-controller is done via the SPI_DATA interface. In transmit mode the16 byte FIFO can be filled as long as it is not full (IRQ_1 can be used if FIFO_full is mapped). In receive mode, the FIFO may be read if one of the following events occurs: • at least one byte is present in the FIFO, i.e. a rising edge on IRQ_0 mapped to /fifoempty • each time a byte is written to FIFO, i.e. a rising edge on IRQ_0 mapped to WRITE_BYTE • 16 bytes have been written to the FIFO, i.e. a rising edge on IRQ_1 mapped to RX_FIFOfull The transceiver should be in buffered mode (MCParam_Buffered_mode = ‘1’). The SPI_DATA interface is then selected if NSS_DATA is low and NSS_CONFIG is high. The operations with SPI_DATA interface are similar to those with SPI_CONFIG except that there is only a data byte (no address byte is required) and except that it is necessary to toggle the NSS_DATA signal back to high and back to low between each transmitted or received byte. © Semtech 2008 www.semtech.com 26 XE1205 Figure 17 shows the write operation during transmit. 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SCK D1(7) D1(6) MOSI D1(5) D1(4) D1(3) x D1(2) D1(1) D1(0) D2(7) D2(6) D2(5) D2(4) D2(0) sample sample sample HZ x x x x x x x x sample x sample x sample x sample x sample x sample x sample x sample x sample HZ sample MISO D2(1) Byte 2 to read sample Byte 1 to read D2(3) D2(2) x HZ shift shift shift shift shift shift shift shift sample shift shift shift shift shift shift shift shift sample NSS_DATA Figure 17 Writing 2 bytes in transmitter mode Figure 18 shows the read operation in receive mode. 1 2 3 4 5 6 7 8 x x x x x 1 2 3 x x 4 5 6 7 8 x x x x SCK x x MOSI x x x D2(7) D2(6) D2(5) D2(4) D2(3) D2(2) D2(1) sample HZ sample D1(2) D1(1) D1(0) sample D1(4) D1(3) sample D1(6) D1(5) sample D1(7) sample HZ sample MISO Byte 2 to read sample Byte 1 to read D2(0) HZ shift shift sample shift shift shift shift shift sample shift sample shift shift sample shift sample shift shift sample shift shift sample shift sample NSS_DATA Figure 18: Reading 2 bytes in receive mode. Note that it is necessary to toggle NSS_DATA signal back to high and then back to low between each transmitted and received byte. © Semtech 2008 www.semtech.com 27 XE1205 7.2 CONFIGURATION AND STATUS REGISTERS The XE1205 has several operating modes, configuration parameters and internal status registers that may be accessed by the microcontroller via the SPI_CONFIG interface. The switching pins SW(1:0) allows switching between one of the four operating modes (sleep, stand-by, receive, transmit) when MCParam_Select_mode is high. If MCParam_Select_mode is low, the modes are defined by the register through the SPI_CONFIG interface and SW(1:0) may be used as an output to control, for example, an antenna switch. 7.2.1 Configuration register: general description The description of the registers which are useful for the user is given in Table 16 below: Name MCParam Size 5x8 Address 0-4 IRQParam TXParam RXParam OSCParam TParam 2 x8 1x8 9x8 2x8 12 x 8 5-6 7 8-16 17-18 19-30 Description Main parameters common to transmit and receive modes Interrupt registers Transmitter parameters Receiver parameters Oscillator parameters Test and special settings Table 16: configuration registers All the bits that are referred to as “reserved” in this section should be set to “0” during write operations. © Semtech 2008 www.semtech.com 28 XE1205 7.2.2 MCParam configuration register (main configuration parameters) The detailed description of the MCParam register is given in Table 17. Chip_mode(1:0) Bits 7-6 Address RW 0 r/w Select_mode 5 0 r/w Buffered_mode 4 0 r/w Data_unidir 3 0 r/w Band(1:0) 2-1 0 r/w Freq_dev(8) Freq_dev(7:0) 0 7-0 0 1 r/w r/w Knx 7 2 r/w Br(6:0) 6-0 2 r/w Name Description Transceiver mode: 00 -> sleep mode 01 -> receive mode 10 -> transmit mode 11 -> stand-by mode Transceiver mode selection: 0 -> mode defined by MCParam_chip_mode, SW(1:0) is an output sleep mode -> SW(1:0) = ”00” receiver mode -> SW(1:0) = “01” transmitter mode -> SW(1:0) = “10” stand-by mode -> SW(1:0) = “00” 1 -> mode defined by SW(1:0) : SW(1:0) = 00 -> sleep mode SW(1:0) = 01 -> receive mode SW(1:0) = 10 -> transmit mode SW(1:0) = 11 -> stand-by mode Enable buffered mode: 0 -> continuous mode 1 -> buffered mode Configure DATA pin 0 -> DATA is a bidirectional pin: input in transmit, output in receive mode 1 -> DATA is an output pin: output in receive mode, high-impedance in transmit mode Frequency band: 01 -> 433 – 435 MHz 10 -> 863 – 870 MHz 11 -> 902 – 928 MHz Frequency deviation MSB Frequency deviation: Δf = int(Freq_dev(8:0)) * FSTEP Where int(x) = integer value of the binary representation of x Example 000000001 -> Δf = FSTEP 111111111 -> Δf = 511*FSTEP all these frequency deviations are available if the data shaping filter is disabled (please refer to Table 11) Konnex mode enable 0 -> default mode -> bit rate defined by MCParam_Br(6:0) 1 -> Konnex mode-> bit rate = 32.7 kbit/s Bit rate Br = 152.34e3/(int(Br) + 1) Where int(x) = integer value of the binary representation of x. Example: 0000001 -> Br = 76.1 kbit/s 1111111 -> Br = 1.19 kbit/s Note: if Konnex mode is enabled, then bit rate = 32.7 kbit/s. © Semtech 2008 www.semtech.com 29 XE1205 Name Freq_lo(15:8) Freq_lo(7:0) (7) Bits 7-0 7-0 Address RW 3 r/w 4 r/w Description LO frequency in 2’s complement: 00…0 -> Flo = middle of the range(6) 0X…X-> Flo = higher than the middle of the range 1X…X-> Flo = lower than the middle of the range Example: 00…001 -> Flo = middle of the range + FSTEP Table 17: MCParam configuration register (6) When frequency band is set to 863-870MHz, 869MHz should be considered as the middle of the range. (7) When frequency band is set to 433-435MHz, MSB is bit 14 and bit 15 is not used. 7.2.3 IRQParam configuration register (IRQ parameters) The detailed description of the IRQParam register is given in Table 18. Name Rx_irq_0(1:0) Bits 7-6 Address 5 RW r/w Rx_irq_1(1:0) 5-4 5 r/w Tx_irq_1 3 5 r/w Fifofull /fifoempty Fifooverrun Start_fill 2 1 0 7 5 5 5 6 r r r/w/c r/w Start_detect 6 6 r/w/c Description Select IRQ_0 source in Rx mode: If Buffered_mode = 0 00 -> IRQ_0 mapped to Pattern signal 01 -> IRQ_0 mapped to RSSI_irq signal 10 -> IRQ_0 mapped to Pattern signal 11 -> IRQ_0 mapped to Pattern signal if Buffered_mode = 1 00 -> IRQ_0 set to ‘0’ 01 -> IRQ_0 mapped to Write_byte signal 10 -> IRQ_0 mapped to /fifoempty signal 11 -> IRQ_0 mapped to Pattern signal Select IRQ_1 source in Rx mode If Buffered_mode = 0 00 -> IRQ_1 mapped to DCLK signal 01 -> IRQ_1 mapped to DCLK signal 10 -> IRQ_1 mapped to DCLK signal 11 -> IRQ_1 mapped to DCLK signal if Buffered_mode = 1 00 -> IRQ_1 set to ‘0’ 01 -> IRQ_1 mapped to Fifofull signal 10 -> IRQ_1 mapped to RSSI_irq signal 11 -> IRQ_1 mapped to RSSI_irq signal Select IRQ_1 source in Tx mode If Buffered_mode = 0 0 or 1 -> IRQ_1 is mapped to DCLK 0 or 1 -> IRQ_0 is set to low if Buffered_mode = 1 0 -> IRQ_1 is mapped to Fifofull signal 1 -> IRQ_1 is mapped to TX_stopped signal (IRQ_0 is mapped to /Fifoempty in Buffered mode) FIFO full (IRQ source) FIFO empty (IRQ source) FIFO overrun error : Write ‘1’ clear FIFO after Overrun occurred FIFO filling selection mode 0 -> The FIFO is filled if a pattern is detected 1 -> The FIFO is filled as long as Start_detect is high Start of FIFO filling If start_fill = ‘0’ goes high when a start sequence is detected writing a ‘1’ clears the bit and wait for a new start sequence If start_fill = ‘1’, 1 -> start to fill the FIFO, 0 -> stop to fill the FIFO. © Semtech 2008 www.semtech.com 30 XE1205 Name Tx_stopped Bits 5 Address 6 RW r Description Transmission stopped ( IRQ source) Start_full 4 6 r/w RSSI_int 3 6 r/w RSSI_signal_detect 2 6 r/w/c RSSI_thr 1-0 6 r/w 0 -> Start transmission when the FIFO is full 1 -> Start transmission when FIFO is not empty (/fifoempty = ‘1’) Enable interrupt RSSI_irq when RSSI_thr is reached: 0 -> no interrupt generated 1 -> interrupt allowed Detection of a signal above RSSI_thr (IRQ source) 0 -> signal power lower than the threshold defined by RSSI_thr. 1 -> signal power equal or greater than the threshold defined by RSSI_thr Writing ‘1’ clear RSSI_signal_detect RSSI threshold for interrupt 00 -> input power ≥ VTHR1 01 -> input power ≥ VTHR2 10 -> input power ≥ VTHR3 11 -> input power ≥ VTHR3 Table 18: IRQParam configuration register 7.2.4 TXParam configuration register (transmitter configuration parameters) The detailed description of the TXParam register is given in Table 19. Name Power(1:0) Bits 7-6 Address 7 RW r/w /Modul 5 7 r/w Filter 4 7 r/w RESERVED Fix_bsync 3-2 1 7 7 r/w r/w RESERVED 0 7 r/w Description Transmitter output power: 00 -> 0 dBm 01 -> 5 dBm 10 -> 10 dBm 11 -> 15 dBm Inhibition of the modulation in transmitter mode: 0 -> modulation 1 -> no modulation Pre-filtering of the bit stream in transmitter mode: 0 -> no filtering 1-> data shaping filter enabled all bit rates defined by Br are available frequency deviations given in Table 11 are available RESERVED 0 -> bit sync in normal environment 1-> bit sync in noisy environment RESERVED Table 19: TXParam configuration register 7.2.5 RXParam configuration register (receiver configuration parameters) The detailed description of the RXParam register is given in Table 20. Disable_bitsync Bits 7 Address 8 RW r/w BW(1:0) 6-5 8 r/w Max_BW 4 8 r/w Name Description Bit synchronizer on/off: 0 -> ON 1 -> OFF Bandwidth of the base band filter(SSB): must be ≥ Freq_dev + Br/2 00 -> 10 kHz 01 -> 20 kHz 10 -> 40 kHz 11 -> 200 kHz Forces the bandwidth of the base band filter to its maximum value © Semtech 2008 www.semtech.com 31 XE1205 Name Bits Address RW Reg_BW(1:0) 3-2 8 r/w Init_filter(1:0) 1-0 8 r/w RSSI 7 9 r/w RSSI_range 6 9 r/w RSSI_out 5-4 9 r FEI 3 9 r/w AFC_start 2 9 r/w AFC_OK 1 9 r/w AFC_disable 0 9 r/w AFC_overflow 7 10 r/w IQAMP 6 10 r/w Rmode 5 10 r/w Pattern 4 10 r/w Psize(1:0) 3-2 10 r/w Description (about 400 kHz SSB) and disables calibration: 0 -> bandwidth defined by BW(1:0) 1 -> bandwidth forced to its maximal value Calibration of the bandwidth of the base band filter: 00 -> calibration at start up 01 -> no calibration 10 -> calibration when the bandwidth of the base band filter changes 11 -> calibration is forced each time 11 is written Base band filter initialization: 00 -> default initialize at start up 01 -> RESERVED 10 -> initialize each time the bandwidth change 11 -> force re-initialization RSSI off/on: 0 -> off 1 -> on Range of the RSSI: 0 -> low range 1 -> high range 00 -> input power ≤ VTHR1 01 -> VTHR1 ≤ input power ≤ VTHR2 10 -> VTHR2 ≤ input power ≤ VTHR3 11 -> VTHR3 ≤ input power Frequency Error Indicator off/on: 0 -> off 1 -> on 0 -> AFC not running process 1 -> AFC running Writing 0 will start the AFC process. At the end of the AFC process, the bit goes automatically back low. Result of the AFC 0 -> AFC operation successful 1 -> AFC operation unsuccessful Disabling the AFC 0 -> the error cancelation is automatically applied on the LO frequency 1 -> the error cancelation is not applied on the LO frequency AFC overflow indicator 0 -> no overflow 1 -> the integrator of the frequency error is too high writing 1 to this bit will reset the integrator IQ amplifier off/on: 0 -> off 1 -> on Linearity/sensitivity mode 0 -> Mode A (high sensitivity) 1 -> Mode B (high linearity) Pattern recognition off/on: 0 -> off 1 -> on Size of the reference Pattern: 00 -> 8 bits 01 -> 16 bits 10 -> 24 bits 11 -> 32 bits © Semtech 2008 www.semtech.com 32 XE1205 Ptol(1:0) Bits 1-0 Address 10 RW r/w FEI_out(15:8) FEI_out(7:0) 7-0 7-0 11 12 r r Name Description Number of tolerated errors for the pattern recognition: 00 -> 0 error 01 -> 1 error 10 -> 2 errors 11 -> 3 errors FEI output in a 2’s complement representation Table 20: RXParam configuration register 7.2.6 Pattern register Name Reg_pattern(31:24) Reg_pattern(23:16) Reg_pattern(15:8) Reg_pattern(7:0) Bits 7-0 7-0 7-0 7-0 Address 13 14 15 16 RW r/w Description 1st byte of the reference pattern 2nd byte of the reference pattern 3rd byte of the reference pattern 4th byte of the reference pattern Table 21: Pattern register This register holds the user supplied reference pattern of 8, 16, 24, or 32 bits (see the RXParam_Psize(1:0) parameter). The first byte of this pattern is always stored in the byte at address 13. If used, the 2nd byte is stored at address 14, the 3rd byte at address 15 and finally the 4th byte at 16. The MSB bit of the reference pattern is always bit 7 of address 13. Comparing the demodulated data, the first bit received is compared with bit 7 (the MSB) of byte address 13. The last bit received is compared with bit 0 (the LSB) in the Pattern register. Table 22 provides an example of pattern recognition with a 32-bit pattern. Byte Address 13 Bit 7 Bit 0 10010011 101 10010011 Byte Address 14 Bit 7 Bit 0 10101010 10101010 Byte Address 15 Bit 7 Bit 0 10010011 10010011 previous bits from demodulator Byte Address 16 Bit 7 Bit 0 10101010 10101010 last bit received Table 22: Pattern recognition example (32 bits) Table 23 provides an example of pattern recognition with an 8-bit pattern. Byte Address 13 Bit 7 Bit 0 10010011 101 10010011 Byte Address 14 Bit 7 Bit 0 Xxxxxxxx previous bits from demodulator last bit received Byte Address 15 Bit 7 Bit 0 Xxxxxxxx Byte Address 16 Bit 7 Bit 0 Xxxxxxxx Table 23: Pattern recognition example (8 bits) © Semtech 2008 www.semtech.com 33 XE1205 7.2.7 OSCParam configuration register (oscillator parameters) Osc Bits 7 Address 17 RW r/w Clkout 6 17 r/w Clkout_freq(2:0) 5-3 17 r/w RESERVED Resxosc 2-0 7-4 17 18 r/w r/w 304 kbit/s_filter 3 18 r/w RESERVED 2-0 18 r/w Name Description Sources of reference frequency 0 -> internal quartz oscillator (for XTAL or TCXO) 1 -> external signal applied on pin XTA (CMOS type signal, external clock) Enable clkout 0 -> no signal provided on pin CLKOUT 1 -> Signal at reference frequency divided by 2, 4, 8,16, 32 provided on CLKOUT (19.5 MHz down to 1.22 MHz) Frequency of signal provided on CLKOUT: 000 -> 1.22 MHz 001 -> 2.44 MHz 010 -> 4.87 MHz 011 -> 9.75 MHz others -> 19.5 MHz RESERVED Select the value of the resistor placed between TKA and TKB in order to use the transceiver with a crystal operating on its third overtone 0000 -> no resistor ( 3.8 MΩ) 0001 -> 1.48 kΩ 0010 -> 1.56 kΩ 0011 -> 1.66 kΩ 0100 -> 1.78 kΩ 0101 -> 1.91 kΩ 0110 -> 2.07 kΩ 0111 -> 2.26 kΩ 1000 -> 2.55 kΩ 1001 -> 2.81 kΩ 1010 -> 3.22 kΩ 1011 -> 3.79 kΩ 1100 -> 4.65 kΩ 1101 -> 6.04 kΩ 1110 -> 8.79 kΩ 1111 -> 16.55 kΩ 304.7 kbit/s Tx filter 0 -> disabled 1 -> enabled RESERVED Table 24: OSCParam configuration register © Semtech 2008 www.semtech.com 34 XE1205 7.2.8 ADParam configuration register (additional settings) Most of the parameters of this category are for test purposes. Some of them can be used to supersede settings that are described in previous sections to optimize special applications. These last parameters are described in the table below. Name Bits Address RW Add_BW 1 19 r/w Description Change of RXParam_BW(1:0) decoding, allowing additional bandwidths for the base-band filter to be selected: Add_BW = 0 -> default values of RXParam_BW(1:0): RXParam_BW(1:0) = 00 => 10 kHz RXParam_BW(1:0) = 01 => 20 kHz RXParam_BW(1:0) = 10 => 40 kHz RXParam_BW(1:0) = 11 => 200 kHz Add_BW = 1 -> new bandwidth values: RXParam_BW(1:0) = 00 => 14.3 kHz RXParam_BW(1:0) = 01 => 28.5 kHz RXParam_BW(1:0) = 10 => 66.7 kHz RXParam_BW(1:0) = 11 => 100 kHz Low_BW 2 19 r/w Flag allowing selection of base-band filter bandwidths lower than 10 kHz: 0 -> default values given by RXParam_BW(1:0) and TParam_Add_BW 1-> bandwidths defined by TParam_Code_BW(8:0) Code_BW(8:0) 6-0 21 7-6 22 r/w Low base-band filter bandwidths, when TParam_Low_BW = 1: Code_BW(8:0) = 139 => 9 kHz Code_BW(8:0) = 160 => 8 kHz Code_BW(8:0) = 185 => 7 kHz MSB Code_BW(8) = bit 6 of address 21 Add_HPF(2:0) 5-3 22 r/w Chg_OSR 4 27 r/w OSR 7-0 28 r/w Cut-off frequency of the HPF stages allowing cancellation of the DC and low-frequency offsets in the baseband circuit: 0 0 0 -> 660 Hz (default value) 0 0 1 -> 1.48 kHz 0 1 0 -> 1.75 kHz 0 1 1 -> 1.96 kHz 1 0 0 -> 2.55 kHz 1 0 1 -> 3.34 kHz 1 1 0 -> 5.11 kHz 1 1 1 -> 10.2 kHz Flag allowing the over-sampling ratio of the bit synchronizer to be changed: 0 -> default OSR (32) 1 -> OSR defined by TParam_OSR(7:0) Over-sampling ratio of the bit synchronizer when TParam_Chg_OSR = 1 Actual OSR = TParam_OSR(7:0) + 1 Table 25: Useful special settings from TParam register © Semtech 2008 www.semtech.com 35 XE1205 7.3 OPERATING MODES The XE1205 has four main operating modes illustrated in Table 26 below. These modes are defined by register MCParam_Chip_mode(1:0) when bit MCParam_Select_mode is low and defined by SW(1:0) pins when MCParam_Select_mode is high. Please note that in both cases the changes will be applied to the transceiver upon the rising edge of the NSS_CONFIG signal (ie NSS_CONFIG must be set low even when using SW(1:0) as inputs). 00 SW(1:0) mode Output SW(1:0) value 00 Operating Mode Sleep Enabled blocks of the transceiver - 0 01 Output 01 Receive 0 10 Output 10 Transmit 0 11 Output 11 Standby Quartz oscillator, Frequency synthesizer, Receiver Quartz oscillator, Frequency synthesizer, Transmitter Quartz oscillator 1 00 Input 00 Sleep - 1 01 Input 01 Receive 1 10 Input 10 Transmit 1 11 Input 11 Standby Quartz oscillator, Frequency synthesizer, Receiver Quartz oscillator, Frequency synthesizer, Transmitter Quartz oscillator MCParam_Select_mode MCParam_Chip_mode(1:0) 0 Table 26: Operating modes 7.3.1 XE1205 switching time using SPI_CONFIG interface. The transceiver is able to switch between modes by using the SPI_CONFIG interface.(MCParam_Chip_mode(1:0)) or by using the pin SW(1:0). This section describes the switching sequence of the transceiver when register MCParam_Select_mode is low i.e. the configuration is done via the SPI_CONFIG and SW(1:0) is an output. The sequence from sleep mode to receive mode via stand-by mode is shown in Figure 19Error! Reference source not found. TS_SRE is the receiver wake-up time when the oscillator is enabled, defined as the initialization time for the frequency synthesizer and the base band filter. The base band filter initialization and calibration processes occur when the transceiver switches from stand-by to receive. Programmed mode Stand-by Sleep Receive NSS_CONFIG Actual mode Sleep Stand-by TS_OS Receive TS_SRE Figure 19 Sequence from sleep mode to receive mode via standby mode. The sequence from sleep to transmit mode via stand-by mode is displayed in Figure 20. TS_STR is the initialization time of the frequency synthesizer and the power amplifier. © Semtech 2008 www.semtech.com 36 XE1205 Programmed mode Sleep Transmit Stand-by NSS_CONFIG Actual mode Sleep Stand-by Transmit TS_OS TS_STR Figure 20. Sequence from sleep to transmit mode via stand-by mode. The sequence from transmit to receive mode is shown in Figure 21. TS_RE is the initialization time of the receiver base band filter when the frequency synthesizer is enabled. The base band filter initialization and calibration processes occur when the transceiver switches from transmit to receive. Programmed mode Transmit Receive NSS_CONFIG Actual mode Transmit Receive TS_RE Figure 21 Sequence from transmit to receive mode. Figure 22 represents the sequence from receive to transmit mode. TS_TR is the initialization time of the power amplifier if the frequency synthesizer is already enabled: Programmed mode Receive Transmit NSS_CONFIG Actual mode Receive Transmit TS_TR Figure 22: Sequence from receiver to transmitter mode © Semtech 2008 www.semtech.com 37 XE1205 Figure 23 illustrates the switching time between two carrier frequencies in receive mode. TS_RFSW is defined as the switching time of the frequency synthesizer and the time needed by the base band filter to reach the steady-state when the boost process is used (Init_filter set to “11”). Actual mode Programmed frequency receive f1 f2 NSS_CONFIG Actual frequency f1 f2 TS_RFSW Figure 23. Switching between two carrier frequencies in receive mode. Figure 24 shows the switching time between two carrier frequencies in transmit mode. TS_TFSW is defined as the switching time of the frequency synthesizer and the time required by the power amplifier to reach the steady-state operating conditions. Actual mode Programmed frequency transmit f1 f2 NSS_CONFIG Actual frequency f1 f2 TS_TFSW Figure 24. Switching between two carrier frequencies in transmit mode. 7.3.2 XE1205 switching time using SW(1:0) pins. If MCParam_Select_mode is high then the transceiver mode is fixed by SW(1:0) MCParam_Chip_mode can be used in read mode but has no effect on the transceiver mode. pins and register 7.4 SELECTION OF THE REFERENCE FREQUENCY The reference clock used for the frequency synthesizer and the internal digital circuitry may be generated by either an external 39 MHz quartz crystal or a TCXO or an external clock. If an external clock is used, the register OSCParam_Osc has to be set high, and the 39 MHz clock signal should to be supplied to the pin “XTA” and the pin “XTB” should be left open. If a TCXO is used, its output signal should be connected to the pin “XTA” and the pin “XTB” should be left. The transceiver can be used with a 39 MHz fundamental mode quartz crystal or with a 3rd overtone crystal. Third overtone operation requires an internal resistor to be connected in parallel with the crystal. This resistor can be connected by programming the register OSCParam_Resxosc(3:0). The required value depends on the crystal © Semtech 2008 www.semtech.com 38 XE1205 specification. OSCParam_Resxosc(3:0) is set to ”0000’’ by default, which selects a parallel resistor of 3.8 MΩ. This default value is used with a 39 MHz crystal enabled on its fundamental frequency. In the case of overtone operation where the microcontroller uses the XE1205 as a clock source, the user should note that during the power up sequence of the XE1205, the oscillator may start and run at its fundamental frequency until the correct value of parallel resistor in the register OSCParam_Resxosc(3:0) is programmed. Before time-sensitive operations an oscillator settling period should be observed to ensure the desired oscillation frequency. 7.5 CLOCK OUTPUT INTERFACE When OSCParam_Clkout is set high, a CLKOUT clock frequency is provided for a microcontroller or external circuitry. A user-programmable frequency divider ratio of 2, 4, 8, 16, 32 is selectable depending on OSCParam_Clkout_freq(2:0). The input frequency of this divider is the 39.0 MHz reference clock; the possible output frequencies are listed in Table 27: OSC_Param_Clkout_freq(1:0) 000 001 010 011 others CLKOUT frequency 1.22 MHz 2.44 MHz 4.87 MHz 9.75 MHz 19.5 MHz Table 27: Frequency divider output When the XE1205 is in sleep mode, CLKOUT is inactive even if bit OSCParam_Clkout remains high. 7.6 DEFAULT SETTINGS AT POWER-UP The internally generated power on reset signal sets the MCParam, RXParam, and TXParam registers to ‘0’. The only exception is the CLKOUT generation: though OSCParam_Clkout is set to low (i.e. disabled) the XE1205 provides a signal at 1.22 MHz on the pin CLKOUT. The first rising edge on the NSS_CONFIG pin causes the registers to be updated and this will result in CLKOUT being disabled. For this reason the first programming sequence should be to enable CLKOUT by setting OSCParam_Clkout to high for applications using CLKOUT. It is recommended to initialize the XE1205 registers immediately after power-up. © Semtech 2008 www.semtech.com 39 XE1205 7.7 PAD CONFIGURATION VERSUS CHIP MODES The table below gives the pad configuration for the different chip modes and settings. CHIP …….Mode Sleep Standby Receive Transmit Comment NSS_CONFIG OUTPUT when Select_mode = ‘0’ else Input OUTPUT when Select mode = ‘0’ else Input INPUT OUTPUT when Select_mode = ‘0’ else Input OUTPUT when Select mode = ‘0’ else Input INPUT OUTPUT when Select_mode = ‘0’ else Input OUTPUT when Select mode = ‘0’ else Input INPUT OUTPUT when Select_mode = ‘0’ else Input OUTPUT when Select mode = ‘0’ else Input INPUT If Select_mode = ‘1’, SW0 and SW1 defines the chip mode If Select_ mode = ‘1’, SW0 and SW1 defines the chip mode NSS_CONFIG has the priority over NSS_DATA NSS_DATA INPUT INPUT INPUT INPUT NSS_DATA is used as data modulation input if Data_unidir is high IRQ_0 IRQ_1 DATA High impedance High impedance High impedance High impedance High impedance High impedance OUTPUT OUTPUT OUTPUT CLKOUT MISO OUTPUT OUTPUT if NSS_CONFIG=’0’ or NSS_DATA = ‘0’ else High Impedance INPUT INPUT OUTPUT OUTPUT if NSS_CONFIG=’0’ or NSS_DATA = ‘0’ else High Impedance INPUT INPUT OUTPUT OUTPUT if NSS_CONFIG=’0’ or NSS_DATA = ‘0’ else High Impedance INPUT INPUT OUTPUT OUTPUT Input if Data_unidir is low ELSE output (refer to 5.2.5) OUTPUT OUTPUT if NSS_CONFIG=’0’ or NSS_DATA = ‘0’ else High Impedance INPUT INPUT PAD SW0 SW1 MOSI SCK Condition on NSS_DATA only applies in buffered mode Table 28. Pad configuration vs chip modes © Semtech 2008 www.semtech.com 40 XE1205 8 APPLICATION INFORMATION This section provides details of the recommended component values for the frequency dependant blocks of the XE1205. Note that these values are dependent upon circuit layout and PCB structure, and that decoupling components have been omitted for clarity. 8.1 MATCHING NETWORK OF THE RECEIVER The schematic of the matching network at the input of the receiver is given below (for a source impedance of 50Ω). CR1 SOURCE RFA XE1205 LR1 RFB CR2 VSS Figure 25 Matching network at the input of the receiver. The typical component values of the matching circuit are shown in Table 29 below. Name CR1 CR2 LR1 Typical Value for 434 MHz 1.5pF 1.5pF 100nH Typical Value for 869 MHz 1.2pF 1.5pF 27nH Typical Value for 915 MHz 1.2pF 1.2pF 27nH Tolerance ± 5% ± 5% ±5% Table 29: Matching network values 8.2 MATCHING NETWORK OF THE TRANSMITTER The optimum load impedances for 15 dBm output power at the three main frequencies are given in Table 30. PA optimum load 0 dBm 5 dBm 10 dBm 15 dBm 434 MHz 174 + j17 117 + j22 111 + j17 89 - j19 869 MHz 120 + j80 115 + j79 95 + j49 80 + j17 915 MHz 103 + j94 101 + j77 95 + j49 84 + j11 Table 30: Optimum load impedances for 15dBm output power © Semtech 2008 www.semtech.com 41 XE1205 The Smith charts in Figure 26 and Figure 27 below show contours of output power versus load impedance when the highest output level is selected (15 dBm mode). 869 MHz 15 dBm 0.8 0.9 1 1.2 1.4 1.6 0.6 1.8 2 0.5 2.4 0.4 3 0.3 4 0.2 5 0.1 10 15 dBm 0.1 0.2 0.5 20 1 20 14 dBm 10 0.1 12 dBm 0.2 5 4 0.3 3 0.4 2.4 0.5 0.6 0.8 0.9 1 1.2 1.4 1.6 1.8 2 Figure 26: Output power vs. load impedance at 869 MHz. © Semtech 2008 www.semtech.com 42 XE1205 915 MHz 15 dBm 1 0.4 0.2 0.1 15 dBm 0.1 0.2 0.5 1 14 dBm 0.1 0.2 12 dBm 0.4 1 Figure 27: Output power vs. load impedance at 915 MHz. © Semtech 2008 www.semtech.com 43 XE1205 The schematic of the recommended matching network at the output of the transmitter is given in Figure 28 below. The two Π-sections are used to provide harmonic filtering to satisfy FCC and ETSI regulations. CT2 LT3 LT1 VDD XE1205 CT3 OUTPUT CT1 CT4 CT5 RFOUT LT2 Figure 28 Matching network at the output of the transmitter. The typical component values of the matching circuit are shown in Table 31 below. Name CT1 CT2 CT3 CT4 CT5 LT1 LT2 LT3 Typical Value for 434 MHz 6.8 pF 1.0 pF 22 pF 6.8 pF 4.7 pF 33 nH 22 nH 22 nH Typical Value for 869 MHz 1.5 pF 0.56 pF 15 pF 3.3 pF 2.2 pF 39 nH 10 nH 8.2 nH Typical Value for 915 MHz 1.8 pF NC 33 pF 3.3 pF 2.2 pF 47 nH 10 nH 8.2 nH Tolerance ± 5% ± 5% ± 5% ± 5% ± 5% ± 5% ± 5% ± 5% Table 31: Matching circuit component values 8.3 VCO TANK The VCO tank circuit should implemented with an inductor and capacitor in parallel. Typical component values are shown in Table 32. Name 434 MHz 869 MHz 915 MHz Tolerance CV1 1.0 pF NC NC ±5% LV1 33 nH 6.8 nH 5.6 nH ±2% Table 32: VCO tank component values © Semtech 2008 www.semtech.com 44 XE1205 8.4 LOOP FILTER OF THE FREQUENCY SYNTHESIZER The loop filter of the frequency synthesizer is shown in Figure 29 below. LFB RL1 XE1205 CL2 CL1 VSS Figure 29: Frequency synthesizer loop filter Typical recommended component values for the frequency synthesizer loop filter are provided in Table 33 below: Name CL1 CL2 RL1 434 MHz 22 nF 1 nF 560Ω 869 MHz 12 nF 1 nF 560Ω 915 MHz 10 nF 1 nF 680Ω Tolerance ± 5% ± 5% ± 5% Table 33: Typical frequency synthesizer component values For 304.7 kbit/s operation, refer to section 6. © Semtech 2008 www.semtech.com 45 XE1205 8.5 REFERENCE CRYSTAL FOR THE FREQUENCY SYNTHESIZER For narrow band applications, where users select the lowest frequency deviation and the narrowest baseband filter, the crystal for reference oscillator of the frequency synthesizer should have the following typical characteristics: Name Fs Description Nominal frequency CL Rm Cm C0 Δfs(0) Δfs(ΔT) Load capacitance for fs (on-chip) Motional resistance Motional capacitance Shunt capacitance Calibration tolerance at 25 °C Stability over temperature range (-40 °C to 85 °C) Aging tolerance in first 5 years Δfs(Δt) Min. value - Typ. value 39.0 MHz (fundamental) 8 pF - Max. value 40Ω 30 fF 7 pF 10 ppm 10 ppm 5 ppm Table 34: Crystal characteristics The electrical specifications given in section 4.2.2 are valid for a crystal having the specifications given in Table 34. For wide band applications requiring less frequency stability, the values for Δfs(0), Δfs(ΔT), and/or Δfs(Δt) can be relaxed. In this case foffset + BWssb should be lower than BWfilter, where foffset is the offset (error) on the carrier frequency (the sum of Δfs(0), Δfs(ΔT), and/or Δfs(Δt)), BWssb is the single side-band bandwidth of the signal, and BWfilter is the single side-band bandwidth of the base-band filter. The overtone crystal usage can result in higher oscillator start-up time than fundamental mode. The overtone crystal should be designed for Cload = 8 to 10 pF and has parameters of Rm < 60Ω, C0 < 7 pF. © Semtech 2008 www.semtech.com 46 XE1205 9 PACKAGING INFORMATION XE1205 comes in a 48-lead VQFN 8X8 package as shown in Figure 30 below. Figure 30: Package dimensions © Semtech 2008 www.semtech.com 47 XE1205 © Semtech 2008 All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. 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