Document Number: MMA65XX Rev. 3, 03/2012 Freescale Semiconductor Data Sheet: Technical Information Dual-Axis SPI Inertial Sensor MMA65xx, a SafeAssure solution, is a SPI-based, dual-axis, medium-g, overdamped lateral accelerometer designed for use in Automotive Airbag systems. MMA65xx Features • • • • • • • • ±80g, ±105g or ±120g full-scale range, independently specified for each axis 3.3V or 5V single supply operation SPI-compatible serial interface 12-bit digital signed or unsigned SPI data output Independent programmable arming functions for each axis Twelve low-pass filter options, ranging from 50 Hz to 1000 Hz Optional offset cancellation with > 6s averaging period and < 0.25 LSB/s slew rate Pb-Free 16-Pin QFN, 6 by 6 Package Referenced Documents • AECQ100, Revision G, dated May 14, 2007 (http://www.aecouncil.com/) ORDERING INFORMATION Device X-Axis Range Y-Axis Range Shipping MMA6519KW ±80g ±80g Tubes MMA6525KW ±105g ±105g Tubes MMA6527KW ±120g ±120g Tubes MMA6519KWR2 ±80g ±80g Tape & Reel MMA6525KWR2 ±105g ±105g Tape & Reel MMA6527KWR2 ±120g ±120g Tape & Reel For user register array programming, please consult your Freescale representative. © 2011-2012 Freescale Semiconductor, Inc. All rights reserved. Bottom View 16 LEAD QFN 6 mm by 6 mm CASE 2086-01 VCC VCC CS VREG SCLK VREGA MOSI MISO C1 C3 C2 MMA65xx VSSA VSS VPP/TEST ARM_X ARM_Y Figure 1. Application Diagram Table 1. External Component Recommendations Ref Des Type Description Purpose C1 Ceramic 0.1 μF, 10%, 10V Minimum, X7R VCC Power Supply Decoupling C2 Ceramic 1 μF, 10%, 10V Minimum, X7R Voltage Regulator Output Capacitor (CVREG) C3 Ceramic 1 μF, 10%, 10V Minimum, X7R Voltage Regulator Output Capacitor (CVREGA) MMA65xx 2 Sensor Freescale Semiconductor, Inc. VCC VREG VREGA VSS Offset IIR Low-Pass Filter SINC Filter Over-Damped Y-Axis g-Cell Linear Interpolation Compensation Cancellation Output Scaling ARM_Y ARM_Y Offset Monitor Clock CRC Y-Axis SPI Generation Y-Axis Register Array ΣΔ Converter VREG Clock & bias Generator VREGA VCC CS SPI 1 MHz Self Test Analog Regulator Clock 8 MHz 1 MHz Oscillator Voltage Monitor Regulator Monitoring VREGA OTP Array Memory SPI Mismatch Verification I/O SCLK MOSI MISO VREG Clock & bias Generator Over-Damped X-Axis g-Cell Digital ΣΔ Converter X-Axis Register Array X-Axis Clock CRC SPI Generation Offset Monitor IIR SINC Filter Low-Pass Filter Compensation Linear Interpolation Offset Cancellation Output Scaling ARM_X ARM_X xxxxxxx xxxxxxx X: 0 g Y: -1 g X: +1 g Y: 0 g xxxxxxx xxxxxxx xxxxxxx xxxxxxx Figure 2. Internal Block Diagram X: 0 g Y: +1 g xxxxxxx xxxxxxx X: -1 g Y: 0 g X: 0 g Y: 0 g X: 0 g Y: 0 g EARTH GROUND Figure 3. Device Orientation Diagram MMA65xx(K)W AWLYWWZ Data Code Legend: A: Assembly Location WL: Wafer Lot Number (g-cell Lot Number) Y: Year WW: Work Week Z: Assembly Lot Number Figure 4. Part Marking MMA65xx Sensor Freescale Semiconductor, Inc. 3 VSSA N/C N/C Pin Connections VSSA 1 16 15 14 13 VREGA 1 12 CS 17 VSS 2 11 MOSI VREG 3 10 SCLK 9 VCC 5 6 7 8 ARM_Y/PCM_Y ARM_X/PCM_X TEST/VPP MISO VSS 4 Figure 5. Top View, 16-Pin QFN Package Table 2. Pin Descriptions Pin Pin Name Formal Name 1 VREGA Analog Supply 2 VSS Digital GND 3 VREG Digital Supply 4 VSS Digital GND This pin is the power supply return node for the digital circuitry. ARM_Y/ PCM_Y Y-Axis Arm Output / PCM Output The function of this pin is configurable via the DEVCFG register as described in Section 3.1.6.6. When the arming output is selected, ARM_Y can be configured as an open drain, active low output with a pullup current; or an open drain, active high output with a pulldown current. Alternatively, this pin can be configured as a digital output with PCM signal proportional to the Y axis acceleration data. Reference Section 3.8.10 and Section 3.8.11. If unused, this pin must be left unconnected. 6 ARM_X/ PCM_X X-Axis Arm Output / PCM Output The function of this pin is configurable via the DEVCFG register as described in Section 3.1.6.6. When the arming output is selected, ARM_X can be configured as an open drain, active low output with a pullup current; or an open drain, active high output with a pulldown current. Alternatively, this pin can be configured as a digital output with a PCM signal proportional to the X-axis acceleration data. Reference Section 3.8.10 and Section 3.8.11. If unused, this pin must be left unconnected. 7 TEST / VPP Programming Voltage This pin provides the power for factory programming of the OTP registers. This pin must be connected to VSS in the application. 8 MISO SPI Data Out This pin functions as the serial data output for the SPI port. 9 VCC Supply This pin supplies power to the device. An external capacitor must be connected between this pin and VSS. Reference Figure 1. 10 SCLK SPI Clock This input pin provides the serial clock to the SPI port. An internal pulldown device is connected to this pin. 11 MOSI SPI Data In This pin functions as the serial data input to the SPI port. An internal pulldown device is connected to this pin. 5 Definition This pin is connected to the power supply for the internal analog circuitry. An external capacitor must be connected between this pin and VSSA. Reference Figure 1. This pin is the power supply return node for the digital circuitry. This pin is connected to the power supply for the internal digital circuitry. An external capacitor must be connected between this pin and VSS. Reference Figure 1. 12 CS Chip Select This input pin provides the chip select for the SPI port. An internal pullup device is connected to this pin. 13 VSSA Analog GND This pin is the power supply return node for analog circuitry. 14 NC No Connect Not internally connected. This pin can be unconnected or connected to VSS in the application. 15 NC No Connect Not internally connected. This pin can be unconnected or connected to VSS in the application. 16 VSSA Analog GND This pin is the power supply return node for analog circuitry. 17 PAD Die Attach Pad Corner Pads This pin is the die attach flag, and is internally connected to VSS. Reference Section 5 for die attach pad connection details. The corner pads are internally connected to VSS. MMA65xx 4 Sensor Freescale Semiconductor, Inc. 2 Electrical Characteristics 2.1 Maximum Ratings Maximum ratings are the extreme limits to which the device can be exposed without permanently damaging it. # Rating Symbol Value Unit 1 Supply Voltage VCC -0.3 to +7.0 V (3) 2 VREG, VREGA VREG -0.3 to +3.0 V (3) 3 SCLK, CS, MOSI,VPP/TEST VIN -0.3 to VCC + 0.3 V (3) 4 ARM_X, ARM_Y VIN -0.3 to VCC + 0.3 V (3) 5 MISO (high impedance state) VIN -0.3 to VCC + 0.3 V (3) 6 Powered Shock (six sides, 0.5 ms duration) gpms ±1500 g (5,18) 7 Unpowered Shock (six sides, 0.5 ms duration) gshock ±2000 g (5,18) 8 Drop Shock (to concrete surface) hDROP 1.2 m (5) 9 10 11 Electrostatic Discharge Human Body Model (HBM) Charge Device Model (CDM) Machine Model (MM) VESD VESD VESD ±2000 ±750 ±200 V V V (5) (5) (5) 12 Storage Temperature Range Tstg -40 to +125 °C (5) 13 Thermal Resistance - Junction to Case qJC 2.5 °C/W (14) 2.2 Operating Range The operating ratings are the limits normally expected in the application and define the range of operation. # Characteristic 14 15 Supply Voltage Standard Operating Voltage, 3.3V Standard Operating Voltage, 5.0V 16 Operating Ambient Temperature Range Verified by 100% Final Test 17 Power-on Ramp Rate (VCC) Symbol Min Typ Max VCC VL +3.135 VTYP +3.3 +5.0 VH +5.25 TA TL -40 — VCC_r 0.000033 — Units V V (15) (15) TH +105 C (1) 3300 V/μs (19) MMA65xx Sensor Freescale Semiconductor, Inc. 5 2.3 Electrical Characteristics - Power Supply and I/O VL ≤ (VCC - VSS) ≤ VH, TL ≤ TA ≤ TH, |ΔTA| < 25 K/min unless otherwise specified # Characteristic 18 Supply Current 19 20 21 22 23 24 25 26 Power Supply Monitor Thresholds (See Figure 9) VCC Under Voltage (Falling) VREG Under Voltage (Falling) VREG Over Voltage (Rising) VREGA Under Voltage (Falling) VREGA Over Voltage (Rising) Power Supply Monitor Hysteresis VCC Under Voltage VREG Under Voltage, VREG Over Voltage VREGA Under Voltage, VREGA Over Voltage Power Supply RESET Thresholds (See Figure 6, and Figure 9) VREG Under Voltage RESET (Falling) 27 VREG Under Voltage RESET (Rising) 28 29 VREG RESET Hysteresis 30 31 Internally Regulated Voltages VREG VREGA 32 33 External Filter Capacitor (CVREG, CVREGA) Value ESR (including interconnect resistance) 34 35 Power Supply Coupling 50 kHz ≤ fn ≤ 300 kHz 4 MHz ≤ fn ≤ 100 MHz Symbol Min Typ Max Units IDD 4.0 — 8.0 mA (1) VCC_UV_f VREG_UV_f VREG_OV_r VREGA_UV_f VREGA_OV_r 2.74 2.10 2.65 2.20 2.65 — — — — — 3.02 2.25 2.85 2.35 2.85 V V V V V (3,6) (3,6) (3,6) (3,6) (3,6) VHYST VHYST VHYST 65 20 20 100 100 100 110 210 150 mV mV mV (3) (3) (3) * * VREG_UVR_f VREG_UVR_r VHYST 1.764 1.876 80 — — — 2.024 2.152 140 V V mV (3,6) (3,6) (3) * * VREG VREGA 2.42 2.42 2.50 2.50 2.58 2.58 V V (1,3) (1,3) CVREG, CVREGA ESR 700 — 1000 — 1500 400 nF mΩ (19) (19) — — — — 0.004 0.004 LSB/mv LSB/mv (19) (19) * * * * * * Output High Voltage (MISO, PCM_X, PCM_Y) 36 3.15V ≤ (VCC - VSS) ≤ 3.45V (ILoad = -1 mA) 37 4.75V ≤ (VCC - VSS) ≤ 5.25V (ILoad = -1 mA) * * VOH_3 VOH_5 VCC - 0.2 VCC - 0.4 — — — — V V (2,3) (2,3) Output Low Voltage (MISO, PCM_X, PCM_Y) 38 3.15V ≤ (VCC - VSS) ≤ 3.45V (ILoad = 1 mA) 39 4.75V ≤ (VCC - VSS) ≤ 5.25V (ILoad = 1 mA) * * VOL_3 VOL_5 — — — — 0.2 0.4 V V (2,3) (2,3) Open Drain Output High Voltage (ARM_X, ARM_Y) 40 3.15V ≤ (VCC - VSS) ≤ 3.45V (IARM = -1 mA) 41 4.75V ≤ (VCC - VSS) ≤ 5.25V (IARM = -1 mA) * * VODH_3 VODH_5 VCC - 0.2 VCC - 0.4 — — — — V V (2,3) (2,3) Open Drain Output Pulldown Current (ARM_X, ARM_Y) 42 3.15V ≤ (VCC - VSS) ≤ 3.45V (VARM = 1.5V) 43 4.75V ≤ (VCC - VSS) ≤ 5.25V (VARM = 1.5V) * * IODPD_3 IODPD_5 50 50 — — 100 100 μA μA (2,3) (2,3) Open Drain Output Low Voltage (ARM_X, ARM_Y) 44 3.15V ≤ (VCC - VSS) ≤ 3.45V (IARM = 1 mA) 45 4.75V ≤ (VCC - VSS) ≤ 5.25V (IARM = 1 mA) * * VODH_3 VODH_5 — — — — 0.2 0.4 V V (2,3) (2,3) Open Drain Output Pullup Current (ARM_X, ARM_Y) 46 3.15V ≤ (VCC - VSS) ≤ 3.45V (VARM = 1.5V) 47 4.75 V ≤ (VCC - VSS) ≤ 5.25V (VARM = 1.5V) * * IODPU_3 IODPU_5 -100 -100 — — -50 -50 μA μA (2,3) (2,3) 48 Input High Voltage CS, SCLK, MOSI * VIH 2.0 — — V (3,6) 49 Input Low Voltage CS, SCLK, MOSI * VIL — — 1.0 V (3,6) 50 Input Voltage Hysteresis CS, SCLK, MOSI * VI_HYST 0.125 — 0.500 V (19) * * IIH IIL -70 30 -50 50 -30 70 μA μA (2,3) (2,3) 51 52 Input Current High (at VIH) (SCLK, MOSI) Low (at VIL) (CS) MMA65xx 6 Sensor Freescale Semiconductor, Inc. 2.4 Electrical Characteristics - Sensor and Signal Chain VL ≤ (VCC - VSS) ≤ VH, TL ≤ TA ≤ TH, |ΔTA| < 25 K/min unless otherwise specified. # Characteristic 53 54 55 Digital Sensitivity (SPI) 80g (12-Bit Output) 105.5g (12-Bit Output) 120g (12-Bit Output) 56 57 58 Sensitivity Error TA = 25°C -40°C ≤ TA ≤ 105°C -40°C ≤ TA ≤ 105°C,VCC_UV_f ≤ VCC - VSS ≤ VL Symbol Min Typ Max Units * * * SENS SENS SENS — — — 24.0 18.2 16.0 — — — LSB/g LSB/g LSB/g (1,9) (1,9) (1,9) * * ΔSENS ΔSENS ΔSENS -4 -5 -5 — — — +4 +5 +5 % % % (1) (1) (3) 59a 60a 61a 62a Offset at 0g (105.5g 120g Range, No Offset Cancellation) 12 bits, unsigned * 12 bits, signed * 12 bits, unsigned, VCC_UV_f ≤ VCC - VSS ≤ VL 12 bits, signed, VCC_UV_f ≤ VCC - VSS ≤ VL OFFSET OFFSET OFFSET OFFSET 1988 -60 1988 -60 2048 0 — — 2108 +60 1988 -60 LSB LSB LSB LSB (1) (1) (3) (3) 63a 64a 65a 66a Offset at 0g (80g Range, No Offset Cancellation) 12 bits, unsigned 12 bits, signed 12 bits, unsigned, VCC_UV_f ≤ VCC - VSS ≤ VL 12 bits, signed, VCC_UV_f ≤ VCC - VSS ≤ VL * * OFFSET OFFSET OFFSET OFFSET 1968 -80 1968 -80 2048 0 — — 2128 +80 1968 -80 LSB LSB LSB LSB (1) (1) (3) (3) 67b 68b 69b 70b Offset at 0g (With Offset Cancellation) 12 bits, unsigned 12 bits, signed 12 bits, unsigned, VCC_UV_f ≤ VCC - VSS ≤ VL 12 bits, signed, VCC_UV_f ≤ VCC - VSS ≤ VL * * OFFSET OFFSET OFFSET OFFSET 2047.75 -0.25 2047.75 -0.25 2048 0 — — 2048.25 +0.25 2048.25 +0.25 LSB LSB LSB LSB (9,7) (9,7) (9) (9) OFFTHRPOS OFFTHRNEG — — 100 -100 — — LSB LSB (7) (7) 71 72 Offset Monitor Thresholds Positive Threshold (12 bits signed) Negative Threshold (12 bits signed) 73 74 75 76 Range of Output (SPI, 12 bits, unsigned) Normal Fault Response Code Unused Codes Unused Codes RANGE FAULT UNUSED UNUSED 128 — 1 3969 — 0 — — 3968 — 127 4095 LSB LSB LSB LSB (7) (7) (7) (7) 77 78 79 Range of Output (SPI, 12 bits, signed) Normal Unused Codes Unused Codes RANGE UNUSED UNUSED -1920 -2047 1921 — — — 1920 -1921 2047 LSB LSB LSB (7) (7) (7) NLOUT -1 — 1 % FSR (3) nRMS nP-P — — — — 1 3 LSB LSB (3) (3) VZX VYX VZY VXY -4 -4 -4 -4 — — — — +4 +4 +4 +4 % % % % (3) (3) (3) (3) 80 Nonlinearity 81 82 System Output Noise RMS (12 bits, All Ranges, 400 Hz, 3-pole LPF) Peak to Peak (12 bits, All Ranges, 400 Hz, 3-pole LPF) 83 84 85 86 Cross-Axis Sensitivity VZX VYX VZY VXY * * * * * MMA65xx Sensor Freescale Semiconductor, Inc. 7 2.5 Self Test VL ≤ (VCC - VSS) ≤ VH, TL ≤ TA ≤ TH, |ΔTA| < 25 K/min unless otherwise specified. # Characteristic 87 88 89 90 91 92 93 94 95 Self Test Output Change (Ref Section 3.6) 80g, TA = 25°C 80g, -40°C ≤ TA ≤ 105°C 80g, -40°C ≤ TA ≤ 105°C, VCC_UV_f ≤ VCC - VSS ≤ VL 105.5g, TA = 25°C 105.5g, -40°C ≤ TA ≤ 105°C 105.5g, -40°C ≤ TA ≤ 105°C, VCC_UV_f ≤ VCC - VSS ≤ VL 120g, TA = 25°C 120g, -40°C ≤ TA ≤ 105°C 120g, -40°C ≤ TA ≤ 105°C, VCC_UV_f ≤ VCC - VSS ≤ VL 96 97 Self Test Cross-Axis Output Y-Axis Output with X-Axis Self Test X-Axis Output with Y-Axis Self Test 98 99 Self Test Output Accuracy Δ from Stored Value, including Sensitivity Error -40°C ≤ TA ≤ 105°C (Ref Section 3.6) * * * * * * * Symbol Min Typ Max Units ΔST80_25 ΔST80_ΔT ΔST80_ΔTΔV ΔST105_25 ΔST105_ΔT ΔST105_ΔTΔV ΔST120_25 ΔST120_ΔT ΔST120_ΔTΔV ΔSTMIN 582 545 545 442 414 414 387 363 363 ΔSTNOM 727 727 727 553 553 553 484 484 484 ΔSTMAX 872 909 909 663 690 690 581 605 605 LSB LSB LSB LSB LSB LSB LSB LSB LSB (1) (1) (3) (1) (1) (3) (1) (1) (3) ΔSTCrossAxis ΔSTCrossAxis -10 -10 — — +10 +10 LSB LSB (1) (1) ΔSTACC -10 — +10 % (3) 100 Sigma Delta Modulator Range X/Y-Axis, Any Range Positive/Negative gADCl_Clip 375 400 450 g (19) 101 Acceleration (without hitting internal g-cell stops) X/Y-Axis, Any Range Positive/Negative gg-cell_Clip 500 560 600 g (19) MMA65xx 8 Sensor Freescale Semiconductor, Inc. 2.6 Dynamic Electrical Characteristics - Signal Chain VL ≤ (VCC - VSS) ≤ VH, TL ≤ TA ≤ TH, |ΔTA| < 25 K/min unless otherwise specified. # Characteristic 102 103 104 DSP Sample Rate (LPF 0,1,2,3,4,5) DSP Sample Rate (LPF 8,9,10,11,12,13) Interpolation Sample Rate 105 106 Data Path Latency (excluding g-cell and Low Pass Filter) TS = 64/fOSC TS = 128/fOSC Symbol Min Typ Max Units tS tS tINTERP — — — 64/fOSC 128/fOSC tS/2 — — — s s s (7) (7) (7) * * tDataPath_8 tDataPath_16 33.0 51.9 34.8 54.6 36.5 57.4 μs μs (7,16) (7,16) * * * * * * fC0(LPF) fC1(LPF) fC2(LPF) fC3(LPF) fC4(LPF) fC5(LPF) 95 285 380 760 950 380 100 300 400 800 1000 400 105 315 420 840 1050 420 Hz Hz Hz Hz Hz Hz (3,7,17) (3,7,17) (3,7,17) (3,7,17) (3,7,17) (3,7,17) * * * * * * fC8(LPF) fC9(LPF) fC10(LPF) fC11(LPF) fC12(LPF) fC13(LPF) 47.5 142.5 190 380 475 190 50 150 200 400 500 200 52.5 157.5 210 420 525 210 Hz Hz Hz Hz Hz Hz (3,7,17) (3,7,17) (3,7,17) (3,7,17) (3,7,17) (3,7,17) * * * * * * * OFFAVEPER OFFSLEW OFFRATE OFFCORRP OFFCORRN OFFTHP OFFTHN — — — — — — — 6.29146 0.2384 1049 0.25 -0.25 0.125 0.125 — — — — — — — s LSB/s ms LSB LSB LSB LSB (3,7) (3,7) (3,7) (3,7) (3,7) (3,7) (3,7) ST_ACT100 ST_ACT300 ST_ACT400 ST_ACT800 ST_ACT1000 ST_ACT400_3 — — — — — — — — — — — — 7.00 3.00 2.50 1.70 1.60 2.40 ms ms ms ms ms ms (19) (19) (19) (19) (19) (19) Low-Pass Filter (ts = 8μs) 107 108 109 110 111 112 Cutoff frequency 0: 100 Hz, 4-pole Cutoff frequency 1: 300 Hz, 4-pole Cutoff frequency 2: 400 Hz, 4-pole Cutoff frequency 3: 800 Hz, 4-pole Cutoff frequency 4: 1000 Hz, 4-pole Cutoff frequency 5: 400 Hz, 3-pole Low-Pass Filter (ts = 16μs) 113 114 115 116 117 118 Cutoff frequency 8: 50 Hz, 4-pole Cutoff frequency 9: 150 Hz, 4-pole Cutoff frequency 10: 200 Hz, 4-pole Cutoff frequency 11: 400 Hz, 4-pole Cutoff frequency 12: 500 Hz, 4-pole Cutoff frequency 13: 200 Hz, 3-pole 119 120 121 122 123 124 125 Offset Cancellation (Normal Mode, 12-Bit Output) Offset Averaging Period Offset Slew Rate Offset Update Rate Offset Correction Value per Update Positive Offset Correction Value per Update Negative Offset Correction Threshold Positive Offset Correction Threshold Negative 126 127 128 129 130 131 Self Test Activation Time (CS rising edge to 90% of ST Final Value) Cutoff frequency 0: 100 Hz, 4-pole Cutoff frequency 1: 300 Hz, 4-pole Cutoff frequency 2: 400 Hz, 4-pole Cutoff frequency 3: 800 Hz, 4-pole Cutoff frequency 4: 1000 Hz, 4-pole Cutoff frequency 5: 400 Hz, 3-pole 132 Offset Monitor Bypass Time after Self Test Deactivation tST_OMB — 320 — tS (3,7) 133 Time Between Acceleration Data Requests (Same Axis) tACC_REQ 15 — — μs (3,7,20) 134 135 136 Arming Output Activation Time (ARM_X, ARM_Y, IARM = 200μA) Moving Average and Count Arming Modes (2,3,4,5) Unfiltered Mode Activation Delay (Reference Figure 30) Unfiltered Mode Arm Assertion Time (Reference Figure 30) tARM tARM_UF_DLY tARM_UF_ASSERT 0 0 5.00 — — — 1.51 1.51 6.579 μs μs μs (3,12) (3,12) (3) 137 Sensing Element Natural Frequency fgcell 10791 13464 15879 Hz (19) 138 Sensing Element Cutoff Frequency (-3 dB ref. to 0 Hz) fgcell 0.851 1.58 2.29 kHz (19) 139 Sensing Element Damping Ratio ζgcell 2.46 4.31 9.36 — (19) 140 Sensing Element Delay (@100 Hz) fgcell_delay 70 101 187 μs (19) 141 Sensing Element Step Response (0% - 90%) tStep_gcell — — 200 μs (19) 142 Package Resonance Frequency fPackage 100 — — kHz (19) 143 Package Quality Factor qPackage 1 — 5 (19) MMA65xx Sensor Freescale Semiconductor, Inc. 9 2.7 Dynamic Electrical Characteristics - Supply and SPI VL ≤ (VCC - VSS) ≤ VH, TL ≤ TA ≤ TH, |ΔTA| < 25 K/min unless otherwise specified # Characteristic 144 145 146 Power-On Recovery Time (VCC = VCCMIN to first SPI access) Power-On Recovery Time (Internal POR to first SPI access) SPI Reset Activation Time (CS high to Reset) 147 148 Internal Oscillator Frequency Test Frequency - Divided from Internal Oscillator 149 Serial Interface Timing (See Figure 7, CMISO ≤ 80pF, RMISO ≥ 10kW) Clock (SCLK) period (10% of VCC to 10% of VCC) Symbol Min Typ Max Units tOP tOP tSPI_RESET — — — — — — 10 840 300 ms μs ns (3) (3,7) (7) * fOSC fOSCTST 7.6 0.95 8 1 8.4 1.05 MHz MHz (7) (1) * tSCLK 120 — — ns (3) 150 Clock (SCLK) high time (90% of VCC to 90% of VCC) * tSCLKH 40 — — ns (3) 151 Clock (SCLK) low time (10% of VCC to 10% of VCC) * tSCLKL 40 — — ns (3) 152 Clock (SCLK) rise time (10% of VCC to 90% of VCC) tSCLKR — 15 40 ns (19) 153 Clock (SCLK) fall time (90% of VCC to 10% of VCC) tSCLKF — 15 28 ns (19) 154 CS asserted to SCLK high (CS = 10% of VCC to SCLK = 10% of VCC) tLEAD 60 — — ns (3) 155 CS asserted to MISO valid (CS = 10% of VCC to MISO = 10/90% of VCC) tACCESS — — 60 ns (3) 156 Data setup time (MOSI = 10/90% of VCC to SCLK = 10% of VCC) * tSETUP 20 — — ns (3) 157 MOSI Data hold time (SCLK = 90% of VCC to MOSI = 10/90% of VCC) * tHOLD_IN 10 — — ns (3) 158 MISO Data hold time (SCLK = 90% of VCC to MISO = 10/90% of VCC) * tHOLD_OUT 0 — — ns (3) 159 SCLK low to data valid (SCLK = 10% of VCC to MISO = 10/90% of VCC) * tVALID — — 35 ns (3) 160 SCLK low to CS high (SCLK = 10% of VCC to CS = 90% of VCC) * tLAG 60 — — ns (3) 161 CS high to MISO disable (CS = 90% of VCC to MISO = Hi Z) * tDISABLE — — 60 ns (3) 162 CS high to CS low (CS = 90% of VCC to CS = 90% of VCC) * tCSN 526 — — ns (3) 163 SCLK low to CS low (SCLK = 10% of VCC to CS = 90% of VCC) * tCLKCS 50 — — ns (3) 164 CS high to SCLK high (CS = 90% of VCC to SCLK = 90% of VCC) tCSCLK 50 — — ns (19) 1. Parameters tested 100% at final test. 2. Parameters tested 100% at wafer probe. 3. Parameters verified by characterization 4. (*) Indicates a critical characteristic. 5. Verified by qualification testing. 6. Parameters verified by pass/fail testing in production. 7. Functionality verified 100% via scan. Timing characteristic is directly determined by internal oscillator frequency. 8. N/A 9. Devices are trimmed at 100 Hz with 1000 Hz low-pass filter option selected. Response is corrected to 0 Hz response. 10.Low-pass filter cutoff frequencies shown are -3 dB referenced to 0 Hz response. 11.Power supply ripple at frequencies greater than 900 kHz should be minimized to the greatest extent possible. 12.Time from falling edge of CS to ARM_X, ARM_Y output valid 13.N/A 14.Thermal resistance between the die junction and the exposed pad; cold plate is attached to the exposed pad. 15.Device characterized at all values of VL & VH. Production test is conducted at all typical voltages (VTYP) unless otherwise noted. 16.Data Path Latency is the signal latency from g-cell to SPI output disregarding filter group delays. 17.Filter characteristics are specified independently, and do not include g-cell frequency response. 18.Electrostatic Deflection Test completed during wafer probe. 19.Verified by Simulation. 20.Acceleration Data Request timing constraint only applies for proper operation of the Arming Function MMA65xx 10 Sensor Freescale Semiconductor, Inc. VCC_UV_r VCC VCC_UV_f VREGA_UV_r VREGA_UV_f VREGA Note: VREGA & VREG rise and fall slopes will be dependent on output capacitance and load current VREG_UVR_r VREG_UVR_f VREG POR DEVRES Flag Cleared by User DEVRES Time Figure 6. Power-Up Timing CS tLEAD tSCLKR tSCLK tSCLKF tCSN tSCLKH tCSCLK SCLK tSCLKL tLAG tACCESS tVALID tHOLD_OUT tCLKCS tDISABLE MISO tHOLD_IN tSETUP MOSI Figure 7. Serial Interface Timing MMA65xx Sensor Freescale Semiconductor, Inc. 11 3 Functional Description 3.1 Customer Accessible Data Array A customer accessible data array allows for each device to be customized. The array consists of an OTP factory programmable block and read/write registers for device programmability and status. The OTP and writable register blocks incorporate independent CRC circuitry for fault detection (reference Section 3.2). The writable register block includes a locking mechanism to prevent unintended changes during normal operation. Portions of the array are reserved for factory-programmed trim values. The customer accessible data is shown in the table below. Table 3. Customer Accessible Data Location Bit Function Type Addr Register 7 6 5 4 3 2 1 0 $00 SN0 SN[7] SN[6] SN[5] SN[4] SN[3] SN[2] SN[1] SN[0] $01 SN1 SN[15] SN[14] SN[13] SN[12] SN[11] SN[10] SN[9] SN[8] $02 SN2 SN[23] SN[22] SN[21] SN[20] SN[19] SN[18] SN[17] SN[16] $03 SN3 SN[31] SN[30] SN[29] SN[28] SN[27] SN[26] SN[25] SN[24] $04 STDEFL_X STDEFL_X[7] STDEFL_X[6] STDEFL_X[5] STDEFL_X[4] STDEFL_X[3] STDEFL_X[2] STDEFL_X[1] STDEFL_X[0] $05 STDEFL_Y STDEFL_Y[7] STDEFL_Y[6] STDEFL_Y[5] STDEFL_Y[4] STDEFL_Y[3] STDEFL_Y[2] STDEFL_Y[1] STDEFL_Y[0] $06 FCTCFG_X 1 0 0 0 0 0 0 1 $07 FCTCFG_Y 1 0 0 0 0 0 0 1 $08 PN PN[7] PN[6] PN[5] PN[4] PN[3] PN[2] PN[1] PN[0] $0A DEVCTL RES_1 RES_0 OCPHASE[1] OCPHASE[0] OFFCFG_EN Reserved Reserved Reserved $0B DEVCFG OC Reserved ENDINIT SD OFMON A_CFG[2] A_CFG[1] A_CFG[0] $0C DEVCFG_X ST_X Reserved Reserved Reserved LPF_X[3] LPF_X[2] LPF_X[1] LPF_X[0] $0D DEVCFG_Y ST_Y Reserved Reserved Reserved LPF_Y[3] LPF_Y[2] LPF_Y[1] LPF_Y[0] $0E ARMCFGX Reserved Reserved APS_X[1] APS_X[0] AWS_XN[1] AWS_XN[0] AWS_XP[1] AWS_XP[0] $0F ARMCFGY Reserved Reserved APS_Y[1] APS_Y[0] AWS_YN[1] AWS_YN[0] AWS_YP[1] AWS_YP[0] $10 ARMT_XP AT_XP[7] AT_XP[6] AT_XP[5] AT_XP[4] AT_XP[3] AT_XP[2] AT_XP[1] AT_XP[0] $09 F Invalid Address: “Invalid Register Request” R/W $11 ARMT_YP AT_YP[7] AT_YP[6] AT_YP[5] AT_YP[4] AT_YP[3] AT_YP[2] AT_YP[1] AT_YP[0] $12 ARMT_XN AT_XN[7] AT_XN[6] AT_XN[5] AT_XN[4] AT_XN[3] AT_XN[2] AT_XN[1] AT_XN[0] $13 ARMT_YN AT_YN[7] AT_YN[6] AT_YN[5] AT_YN[4] AT_YN[3] AT_YN[2] AT_YN[1] AT_YN[0] $14 DEVSTAT UNUSED IDE UNUSED DEVINIT MISOERR OFF_Y OFF_X DEVRES $15 COUNT COUNT[7] COUNT[6] COUNT[5] COUNT[4] COUNT[3] COUNT[2] COUNT[1] COUNT[0] $16 OFFCORR_X OFFCORR_X[7] OFFCORR_X[6] OFFCORR_X[5] OFFCORR_X[4] OFFCORR_X[3] OFFCORR_X[2] OFFCORR_X[1] OFFCORR_X[0] $17 OFF_CORR_Y OFFCORR_Y[7] OFFCORR_Y[6] OFFCORR_Y[5] OFFCORR_Y[4] OFFCORR_Y[3] OFFCORR_Y[2] OFFCORR_Y[1] OFFCORR_Y[0] $1C Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved $1D Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved R Type codes F: Factory programmed OTP location R: Read-only register R/W: N/A: Read/write register Not applicable MMA65xx 12 Sensor Freescale Semiconductor, Inc. 3.1.1 Device Serial Number Registers A unique serial number is programmed into the serial number registers of each device during manufacturing. The serial number is composed of the following information: Bit Range Content S12 - S0 Serial Number S31 - S13 Lot Number Serial numbers begin at 1 for all produced devices in each lot, and are sequentially assigned. Lot numbers begin at 1 and are sequentially assigned. No lot will contain more devices than can be uniquely identified by the 13-bit serial number. Depending on lot size and quantities, all possible lot numbers and serial numbers may not be assigned. The serial number registers are included in the OTP shadow register array CRC verification. Reference Section 3.2.1 for details regarding the CRC verification. Beyond this, the contents of the serial number registers have no impact on device operation or performance, and are only used for traceability purposes. 3.1.2 Self Test Deflection Registers (STDEFL_X, STDEFL_Y) These read-only registers provide the nominal self test deflection values for each axis at ambient temperature. The self test value is a positive deflection value, measured at the factory, and factory programmed for each device. The minimum stored value ($00) equates to the minimum deflection specified in Section 2.4 (ΔSTMIN), and the maximum stored value ($FF) equates to the maximum deflection specified in Section 2.4 (ΔSTMAX). Table 4. Self Test Deflection Registers Location Bit Address Register 7 6 5 4 3 2 1 0 $04 STDEFL_X STDEFL_X[7] STDEFL_X[6] STDEFL_X[5] STDEFL_X[4] STDEFL_X[3] STDEFL_X[2] STDEFL_X[1] STDEFL_X[0] $05 STDEFL_Y STDEFL_Y[7] STDEFL_Y[6] STDEFL_Y[5] STDEFL_Y[4] STDEFL_Y[3] STDEFL_Y[2] STDEFL_Y[1] STDEFL_Y[0] When self test is activated, the acceleration reading can be compared to the value in this register. The difference from the measured deflection value, and the nominal deflection value stored in the register shall not fall outside the self test accuracy limits specified in Section 2.4 (ΔSTACC). Reference Section 3.6 for more details on calculating the self test limits. 3.1.3 Factory Configuration Registers The factory configuration registers are one time programmable, read only registers which contain customer specific device configuration information that is programmed by Freescale. Table 5. Factory Configuration Register Location Bit Address Register 7 6 5 4 3 2 1 0 $06 FCTCFG_X 1 0 0 0 0 0 0 1 $07 FCTCFG_Y 1 0 0 0 0 0 0 1 MMA65xx Sensor Freescale Semiconductor, Inc. 13 3.1.4 Part Number Register (PN) The part number register is a one time programmable, read only register which contains two digits of the device part number to identify the axis and range information. The contents of this register have no impact on device operation or performance. Table 6. Part Number Register Location Bit Address Register 7 6 5 4 3 2 1 0 $08 PN PN[7] PN[6] PN[5] PN[4] PN[3] PN[2] PN[1] PN[0] PN Register Value 3.1.5 Decimal HEX X-Axis Range Section 2.4 Y-Axis Range Section 2.4 219 $DB 80 80 225 $E1 105 105 227 $E3 120 120 Device Control Register (DEVCTL The device control register is a read-write register which contains device control operations. The upper 2 bits of this register can be written during both initialization and normal operation. Bits 5 through 0 can be programmed during initialization and then are ignored once the ENDINIT bit is set. Table 7. Device Control Register Location Bit Address Register 7 6 $0A DEVCTL RES_1 RES_0 0 0 Reset Value 5 4 3 OCPHASE[1] OCPHASE[0] OFFCFG_EN 0 0 0 2 1 0 Reserved Reserved Reserved 0 0 0 3.1.5.1 Reset Control (RES_1, RES_0) A series of three consecutive register write operations to the reset control bits in the DEVCTL register will cause a device reset. To reset the internal digital circuitry, the following register write operations must be performed in the order shown below. The register write operations must be consecutive SPI commands in the order shown or the device will not be reset. Register Write to DEVCTL RES_1 RES_0 Effect SPI Register Write 1 0 0 No Effect SPI Register Write 2 1 1 No Effect SPI Register Write 3 0 1 Device RESET The response to the Register Write returns ‘0’ for RES_1 and RES_0, and the existing register value bits 5 through 0. A Register Read of RES_1 and RES_0 returns ‘0’ and terminates the reset sequence. If ENDINIT is cleared, the bits 2 through 0 in the DEVCTL register are modified as described in Section 4.4. If ENDINIT is set, a Register Write will not modify bits 2 through 0 and the response to a Register Read or Write will include the last successful written values for these bits. MMA65xx 14 Sensor Freescale Semiconductor, Inc. 3.1.5.2 Offset Cancellation Phase Control Bits (OCPHASE[1:0]) The offset cancellation phase control bits control the offset cancellation start up phase. These bits can be written at any time ENDINIT is ‘0’ if the OFFCFG_EN bit is set. OFFCFG_EN OCPHASE[1] OCPHASE[0] Writes to OCPHASE[1:0] Offset Cancellation Phase 0 Don’t Care Don’t Care Ignored Continues from the previously written phase (OCPHASE[1:0]) as specified in Section 3.8.4. 1 0 0 Accepted Remains in Start 1 until OFFCFG_EN is cleared or ENDINIT is set 1 0 1 Accepted Remains in Start 2 until OFFCFG_EN is cleared or ENDINIT is set 1 1 0 Accepted Remains in Start 3 until OFFCFG_EN is cleared or ENDINIT is set 1 1 1 Accepted Remains in Normal Mode until OFFCFG_EN is cleared or ENDINIT is set When ENDINIT is set, the OCPHASE[1:0] bits in a write command are ignored and the offset cancellation phase is set to “Normal”. This can only be changed by a device reset. The response to a register read or write of the DEVCTL register once ENDINIT is set will return the last successfully written values of OCPHASE[1:0]. 3.1.5.3 Offset Cancellation Configuration Enable Bit (OFFCFG_EN) The offset cancellation phase configuration enable bit enables modification of the offset cancellation phase control bits (OCPHASE[1:0]) as shown in Section 3.1.5.2 When ENDINIT is set, the OFFCFG_EN bit in a write command is ignored, and the offset cancellation phase is set to “Normal”. This can only be changed by a device reset. The response to a register read or write of the DEVCTL register once ENDINIT is set will return the last successfully written value of OFFCFG_EN. 3.1.5.4 Reserved Bits (DEVCTL[2:0]) Bits 2 through 0 of the DEVCTL register are reserved. A write to the reserved bits must always be logic ‘0’ for normal device operation and performance. 3.1.6 Device Configuration Register (DEVCFG) The device configuration register is a read/write register which contains data for general device configuration. The register can be written during initialization but is locked once the ENDINIT bit is set. This register is included in the writable register CRC check. Refer to Section 3.2.2 for details. Table 8. Device Configuration Register Location Bit Address Register 7 6 5 4 3 2 1 0 $0B DEVCFG OC Reserved ENDINIT SD OFMON A_CFG[2] A_CFG[1] A_CFG[0] 0 0 0 0 0 0 0 0 Reset Value 3.1.6.1 Offset Cancelled Data Selection Bits (OC) The Offset Cancelled Data Selection Bit determines whether the SPI transmitted data is raw data or offset cancelled data. OC SPI Data 0 Offset Cancelled 1 Raw Data If the OC bit is cleared (Offset Cancelled Data), then the Offset Monitor is automatically enabled (OFMON = ‘1’) regardless of the value written to DEVCFG[3]. 3.1.6.2 Reserved Bit (Reserved) Bits 6 of the DEVCFG register is reserved. A write to the reserved bit must always be logic ‘0’ for normal device operation and performance. MMA65xx Sensor Freescale Semiconductor, Inc. 15 3.1.6.3 End of Initialization Bit (ENDINIT) The ENDINIT bit is a control bit used to indicate that the user has completed all device and system level initialization tests, and that the device will operate in normal mode. Once the ENDINIT bit is set, writes to all writable register bits are inhibited except for the DEVCTL register. Once written, the ENDINIT bit can only be cleared by a device reset. The writable register CRC check (reference Section 3.2.2) is only enabled when the ENDINIT bit is set. When ENDINIT is set, the following occurs: • Offset Cancellation is forced to normal mode. OCPHASE[1:0], and OFFCFG_EN remain in their previously set states. • X-Axis Self Test is disabled. ST_X remains in its previously set states. • Y-Axis Self Test is disabled. ST_Y remains in its previously set states. 3.1.6.4 SD Bit The SD bit determines the format of acceleration data results. If the SD bit is set to a logic ‘1’, unsigned results are transmitted, with the zero-g level represented by a nominal value of 512. If the SD bit is cleared, signed results are transmitted, with the zerog level represented by a nominal value of 0. SD Operating Mode 1 Unsigned Data Output 0 Signed Data Output 3.1.6.5 OFMON Bit The OFMON bit determines if the offset monitor circuit is enabled. If the OFMON bit is set to a logic ‘1’, the offset monitor is enabled. Reference Section 3.8.5. If the OFMON bit is cleared, the offset monitor is disabled. OFMON Operating Mode 1 Offset Monitor Circuit Enabled 0 Offset Monitor Circuit Disabled If the OC bit in the DEVCFG register is cleared (Offset Cancelled Data), then the Offset Monitor is automatically enabled (OFMON = ‘1’) regardless of the value written to DEVCFG[3]. 3.1.6.6 ARM Configuration Bits (A_CFG[2:0]) The ARM Configuration Bits (A_CFG[2:0]) select the mode of operation for the ARM_X/PCM_X, ARM_Y/PCM_Y pins. Table 9. Arming Output Configuration A_CFG[2] A_CFG[1] A-CFG[0] Operating Mode Output Type Reference 0 0 0 Arm Output Disabled Hi Impedance 0 0 1 PCM Output Digital Output Section 3.8.11 0 1 0 Moving Average Mode Active High with Pulldown Current Section 3.8.10.1 0 1 1 Moving Average Mode Active Low with Pullup Current Section 3.8.10.1 1 0 0 Count Mode Active High with Pulldown Current Section 3.8.10.2 1 0 1 Count Mode Active Low with Pullup Current Section 3.8.10.2 1 1 0 Unfiltered Mode Active High with Pulldown Current Section 3.8.10.3 1 1 1 Unfiltered Mode Active Low with Pullup Current Section 3.8.10.3 MMA65xx 16 Sensor Freescale Semiconductor, Inc. 3.1.7 Axis Configuration Registers (DEVCFG_X, DEVCFG_Y) The Axis configuration registers are read/write registers which contain axis specific configuration information. These registers can be written during initialization, but are locked once the ENDINIT bit is set. These registers are included in the writable register CRC check. Refer to Section 3.2.2 for details. Table 10. Axis Configuration Registers Location Bit Address Register 7 6 5 4 3 2 1 0 $0C DEVCFG_X ST_X Reserved Reserved Reserved LPF_X[3] LPF_X[2] LPF_X[1] LPF_X[0] $0D DEVCFG_Y ST_Y Reserved Reserved Reserved LPF_Y[3] LPF_Y[2] LPF_Y[1] LPF_Y[0] 0 0 0 0 0 0 0 0 Reset Value 3.1.7.1 Self Test Control (ST_X, ST_Y) The ST_X and ST_Y bits enable and disable the self test circuitry for their respective axes. Self test circuitry is enabled if a logic ‘1’ is written to ST_X, or ST_Y and the ENDINIT bit has not been set. Enabling the self test circuitry results in a positive acceleration value on the enabled axis. Self test deflection values are specified in Section 2.4. ST_X and ST_Y are always cleared following internal reset. When the self test circuitry is active, the offset cancellation block and the offset monitor status are suspended, and the status bits in the Acceleration Data Request Response will indicate “Self Test Active”. Reference Section 3.8.4 and Section 4.2 for details. When the self test circuitry is disabled by clearing the ST_X or ST_Y bit, the offset monitor remains disabled until the time tST_OMB specified in Section 2.6 expires. However, the status bits in the Acceleration Data Request Response will immediately indicate that self test is deactivated. When ENDINIT is set, self test is disabled. This can only be changed by a reset. A Register Write will not modify the ST_X and ST_Y bits and the response to a Register Read or Write will include the last successful written values for these bits. 3.1.7.2 Reserved Bits (Reserved) Bits 6 through 4 of the DEVCFG_X and DEVCFG_Y registers are reserved. A write to the reserved bits must always be logic ‘0’ for normal device operation and performance. 3.1.7.3 Low-Pass Filter Selection Bits (LPF_X[3:0], LPF_Y[3:0]) The Low Pass Filter selection bits independently select a low-pass filter for each axis as shown in Table 11. Refer to Section 3.8.3 for details regarding filter configurations. Table 11. Low Pass Filter Selection Bits LPF_X[3] / LPF_Y[3] LPF_X[2] / LPF_Y[2] LPF_X[1] / LPF_Y[1] LPF_X[0] / LPF_Y[0] Low Pass Filter Selected Nominal Sample Rate (μs) 0 0 0 0 100 Hz, 4-pole 8 0 0 0 1 300 Hz, 4-pole 8 0 0 1 0 400 Hz, 4-pole 8 0 0 1 1 800 Hz, 4-pole 8 0 1 0 0 1000 Hz, 4-pole 8 0 1 0 1 400 Hz, 3-pole 8 0 1 1 0 Reserved Reserved 0 1 1 1 Reserved Reserved 1 0 0 0 50 Hz, 4-pole 16 1 0 0 1 150 Hz, 4-pole 16 1 0 1 0 200 Hz, 4-pole 16 1 0 1 1 400 Hz, 4-pole 16 1 1 0 0 500 Hz, 4-pole 16 1 1 0 1 200 Hz, 3-pole 16 1 1 1 0 Reserved Reserved 1 1 1 1 Reserved Reserved Note:Filter characteristics do not include g-cell frequency response. MMA65xx Sensor Freescale Semiconductor, Inc. 17 3.1.8 Arming Configuration Registers (ARMCFGX, ARMCFGY) The arming configuration registers contain configuration information for the arming function. The values in these registers are only relevant if the arming function is operating in moving average mode, or count mode. These registers can be written during initialization but are locked once the ENDINIT bit is set. Refer to Section 3.1.6.3. These registers are included in the writable register CRC check. Refer to Section 3.2.2 for details. Table 12. Arming Configuration Register Location Bit Address Register 7 6 5 4 $0E ARMCFGX Reserved Reserved APS_X[1] APS_X[0] $0F ARMCFGY Reserved Reserved APS_Y[1] APS_Y[0] 0 0 0 0 Reset Value 3.1.9 3 2 1 0 AWS_XN[1] AWS_XN[0] AWS_XP[1] AWS_XP[0] AWS_YN[1] AWS_YN[0] AWS_YP[1] AWS_YP[0] 1 1 1 1 Reserved Bits (Reserved) Bits 7 through 6 of the ARMCFGX and ARMCFGY registers are reserved. A write to the reserved bits must always be logic ‘0’ for normal device operation and performance. 3.1.9.1 Arming Pulse Stretch (APS_X[1:0], APS_Y[1:0]) The APS_X[1:0] and APS_Y[1:0] bits set the programmable pulse stretch time for the arming outputs. Refer to Section 3.8.10 for more details regarding the arming function. Pulse stretch times are derived from the internal oscillator, so the tolerance on this oscillator applies. Table 13. Arming Pulse Stretch Definitions APS_X[1], APS_Y[1] APS_X[0], APS_Y[0] Pulse Stretch Time (Typical Oscillator) 0 0 0 mS 0 1 16.256 ms - 16.384 ms 1 0 65.408ms - 65.536 ms 1 1 261.888ms - 262.016 ms 3.1.9.2 Arming Window Size (AWS_Xx[1:0], AWS_Yx[1:0]) The AWS_Xx[1:0] & AWS_Yx[1:0] bits have different functions depending on the state of the A_CFG bits in the DEVCFG register. If the arming function is set to moving average mode, the AWS bits set the number of acceleration samples used for the arming function moving average. The number of samples is set independently for each axis and polarity. If the arming function is set to count mode, the AWS bits set the sample count limit for the arming function. The sample count limit is set independently for each axis. Refer to Section 3.8.10 for more details regarding the arming function. Table 14. X-Axis Positive Arming Window Size Definitions (Moving Average Mode) AWS_XP[1] AWS_XP[0] X-Axis Positive Window Size 0 0 2 0 1 4 1 0 8 1 1 16 Table 15. X-Axis Negative Arming Window Size Definitions (Moving Average Mode) AWS_XN[1] AWS_XN[0] X-Axis Negative Window Size 0 0 2 0 1 4 1 0 8 1 1 16 MMA65xx 18 Sensor Freescale Semiconductor, Inc. Table 16. Y-Axis Positive Arming Window Size Definitions (Moving Average Mode) AWS_YP[1] AWS_YP[0] Y-Axis Positive Window Size 0 0 2 0 1 4 1 0 8 1 1 16 Table 17. Y-Axis Negative Arming Window Size Definitions (Moving Average Mode) AWS_YN[1] AWS_YN[0] Y-Axis Negative Window Size 0 0 2 0 1 4 1 0 8 1 1 16 Table 18. Arming Count Limit Definitions (Count Mode) AWS_XN[1] AWS_XN[0] AWS_XP[1] AWS_XP[0] X-Axis Sample Count Limit Don’t Care Don’t Care 0 0 1 Don’t Care Don’t Care 0 1 3 Don’t Care Don’t Care 1 0 7 Don’t Care Don’t Care 1 1 15 Table 19. Arming Count Limit Definitions (Count Mode) 3.1.10 AWS_YN[1] AWS_YN[0] AWS_YP[1] AWS_YP[0] Y-Axis Sample Count Limit Don’t Care Don’t Care 0 0 1 Don’t Care Don’t Care 0 1 3 Don’t Care Don’t Care 1 0 7 Don’t Care Don’t Care 1 1 15 Arming Threshold Registers (ARMT_XP, ARMT_XN, ARMT_YP, ARMT_YN) The arming threshold registers contain the X-axis and Y-axis positive and negative thresholds to be used by the arming function. Refer to Section 3.8.10 for more details regarding the arming function. The arming threshold registers can be written during initialization but are locked once the ENDINIT bit is set. Refer to Section 3.1.6.3. The arming threshold registers are included in the writable register CRC check. Refer to Section 3.2.2 for details. Table 20. Arming Threshold Registers Location Bit Address Register 7 6 5 4 3 2 1 0 $10 ARMT_XP AT_XP[7] AT_XP[6] AT_XP[5] AT_XP[4] AT_XP[3] AT_XP[2] AT_XP[1] AT_XP[0] $11 ARMT_YP AT_YP[7] AT_YP[6] AT_YP[5] AT_YP[4] AT_YP[3] AT_YP[2] AT_YP[1] AT_YP[0] $12 ARMT_XN AT_XN[7] AT_XN[6] AT_XN[5] AT_XN[4] AT_XN[3] AT_XN[2] AT_XN[1] AT_XN[0] $13 ARMT_YN AT_YN[7] AT_YN[6] AT_YN[5] AT_YN[4] AT_YN[3] AT_YN[2] AT_YN[1] AT_YN[0] 0 0 0 0 0 0 0 0 Reset Value MMA65xx Sensor Freescale Semiconductor, Inc. 19 The values programmed into the threshold registers are the threshold values used for the arming function as described in Section 3.8.10. The threshold registers hold independent unsigned 8-bit values for each axis and polarity. Each threshold increment is equivalent to one output LSB. Table 21 shows examples of some threshold register values and the corresponding threshold. Table 21. Threshold Register Value Examples Axis Type Programmed Thresholds Positive Threshold (g) Negative Threshold (g) 50 4.17 -2.08 255 0 10.625 Disabled 24 50 20 2.08 -0.83 80 24 150 75 6.25 -3.125 105.5 18.2 100 50 5.50 -2.75 105.5 18.2 255 0 14.0 Disabled 105.5 18.2 50 20 2.75 -1.10 105.5 18.2 150 75 8.24 -4.12 Range (g) Sensitivity (LSB/g) Positive (Decimal) Negative (Decimal) 80 24 100 80 24 80 If either the positive or negative threshold for one axis is programmed to $00, comparisons are disabled for only that polarity. The arming function still operates for the opposite polarity. If both the positive and negative arming thresholds for one axis are programmed to $00, the Arming function for the associated axis is disabled, and the associated output pin is disabled, regardless of the value of the A_CFG bits in the DEVCFG register. 3.1.11 Device Status Register (DEVSTAT) The device status register is a read-only register. A read of this register clears the status flags affected by transient conditions. Reference Section 4.5 for details on the response for each status condition. Table 22. Device Status Register Location Bit Address Register 7 6 5 4 3 2 1 0 $14 DEVSTAT UNUSED IDE UNUSED DEVINIT MISOERR OFF_Y OFF_X DEVRES 3.1.11.1 Unused Bits (UNUSED) The unused bits have no impact on operation or performance. When read these bits may be ‘1’ or ‘0’. 3.1.11.2 Internal Data Error Flag (IDE) The internal data error flag is set if a customer or OTP register data CRC fault or other internal fault is detected as defined in Section 4.5.5. The internal data error flag is cleared by a read of the DEVSTAT register. If the error is associated with a CRC fault in the writable register array, the fault will be re-asserted and will require a device reset to clear. If the error is associated with the data stored in the fuse array, the fault will be re-asserted even after a device reset. 3.1.11.3 Device Initialization Flag (DEVINIT) The device initialization flag is set during the interval between negation of internal reset and completion of internal device initialization. DEVINIT is cleared automatically. The device initialization flag is not affected by a read of the DEVSTAT register. 3.1.11.4 SPI MISO Data Mismatch Error Flag (MISOERR) The MISO data mismatch flag is set when a MISO Data mismatch fault occurs as specified in Section 4.5.2. The MISOERR flag is cleared by a read of the DEVSTAT register. 3.1.11.5 Offset Monitor Error Flags (OFF_X, OFFSET_Y) The offset monitor error flags are set if the acceleration signal of the associated axis reaches the specified offset limit. The offset monitor error flags are cleared by a read of the DEVSTAT register. 3.1.11.6 Device Reset Flag (DEVRES) The device reset flag is set during device initialization following a device reset. The device reset flag is cleared by a read of the DEVSTAT register. MMA65xx 20 Sensor Freescale Semiconductor, Inc. 3.1.12 Count Register (COUNT) The count register is a read-only register which provides the current value of a free-running 8-bit counter derived from the primary oscillator. A 10-bit pre-scaler divides the primary oscillator frequency by 1024. Thus, the value in the register increases by one count every 128 μs and the counter rolls over every 32.768 ms. Table 23. Count Register Location Bit Address Register 7 6 5 4 3 2 1 0 $15 COUNT COUNT[7] COUNT[6] COUNT[5] COUNT[4] COUNT[3] COUNT[2] COUNT[1] COUNT[0] 0 0 0 0 0 0 0 0 Reset Value 3.1.13 Offset Correction Value Registers (OFFCORR_X, OFFCORR_Y) The offset correction value registers are read-only registers which contain the most recent offset correction increment / decrement value from the offset cancellation circuit. The values stored in these registers indicate the amount of offset correction being applied to the SPI output data. The values have a resolution of 1 LSB. Table 24. Offset Correction Value Register Location Address Bit Register 7 6 5 4 3 2 1 0 $16 OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ X X[7] X[6] X[5] X[4] X[3] X[2] X[1] X[0] $17 OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ OFFCORR_ Y Y[7] Y[6] Y[5] Y[4] Y[3] Y[2] Y[1] Y[0] Reset Value 3.1.14 0 0 0 0 0 0 0 0 Reserved Registers (Reserved) Registers $1C and $1D are reserved. A write to the reserved bits must always be logic ‘0’ for normal device operation and performance. Table 25. Reserved Registers Location Bit Address Register 7 6 5 4 3 2 1 0 $1C Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved $1D Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved 0 0 0 0 0 0 0 0 Reset Value 3.2 Customer Accessible Data Array CRC Verification 3.2.1 OTP Shadow Register Array CRC Verification The OTP shadow register array is verified for errors using a 3-bit CRC. The CRC verification uses a generator polynomial of g(x) = X3 + X + 1, with a seed value = ‘111’. If a CRC error is detected in the OTP array, the IDE bit is set in the DEVSTAT register. 3.2.2 Writable Register CRC Verification The writable registers in the data array are verified for errors using a 3-bit CRC. The CRC verification is enabled only when the ENDINIT bit is set in the DEVCFG register. The CRC verification uses a generator polynomial of g(x) = X3+X+1, with a seed value = ‘111’. If a CRC error is detected in the writable register array, the IDE bit is set in the DEVSTAT register. MMA65xx Sensor Freescale Semiconductor, Inc. 21 3.3 Voltage Regulators Separate internal voltage regulators supply the analog and digital circuitry. External filter capacitors are required, as shown in Figure 1. The voltage regulator module includes voltage monitoring circuitry which indicates a device reset until the external supply and all internal regulated voltages are within predetermined limits. A reference generator provides a stable voltage which is used by the ΣΔ converters. VCC BANDGAP REFERENCE VREGA = 2.50 V VOLTAGE REGULATOR VREGA PRIMARY OSCILLATOR BIAS GENERATOR TRIM TRIM ΣΔ CONVERTER REFERENCE GENERATOR VREF = 1.250 V DIGITAL LOGIC DSP TRACKING REGULATOR Tracks VREGA OTP ARRAY VREG = 2.50 V VREG Figure 8. Power Supply Block Diagram VCCUV VCC VREG VREGOV VREGUV MONITOR BANDGAP GROUND LOSS MONITOR VBGMON VREGA SET DEVRES Flag VREGAUV VREGAOV VREG VREF VREFOV VREFUV VPORREF POR Note: No external access to reference voltage Limits verified by characterization only Figure 9. Voltage Monitoring MMA65xx 22 Sensor Freescale Semiconductor, Inc. 3.3.1 CVREG Failure Detection The digital supply voltage regulator is designed to be unstable with low capacitance. If the connection to the VREG capacitor becomes open, the digital supply voltage will oscillate and cause either an under voltage, or over voltage failure within one internal sample time. This failure will result in one of the following: 1. The DEVRES flag in the DEVSTAT register will be set. The device will respond to SPI acceleration requests as defined in Table 30. 2. The device will be held in RESET and be non-responsive to SPI requests. 3.3.2 CVREGA Failure Detection The analog supply voltage regulator is designed to be unstable with low capacitance. If the connection to the VREGA capacitor becomes open, the analog supply voltage will oscillate and cause either an under voltage, or over voltage failure within one internal sample time. The DEVRES flag in the DEVSTAT register will be set. The device will respond to SPI acceleration requests as defined in Table 30. 3.3.3 VSS and VSSA Ground Loss Monitor The device detects the loss of ground connection to either VSS or VSSA. A loss of ground connection to VSS will result in a VREG overvoltage failure. A loss of ground connection to VSSA will result in a VREG undervoltage failure. Both failures result in a device reset. 3.3.4 SPI Initiated Reset In addition to voltage monitoring, a device reset can be initiated by a specific series of three write operations involving the RES_1 and RES_0 bits in the DEVCTL register. Reference Section 3.1.5.1. for details regarding the SPI initiated reset. 3.4 Internal Oscillator The device includes a factory trimmed oscillator as specified in Section 2.7. 3.4.1 Oscillator Monitor The COUNT register in the customer accessible array is a read-only register which provides the current value of a free-running 8-bit counter derived from the primary oscillator. A 10-bit pre-scaler divides the primary oscillator by 1024. Thus, the value in the COUNT register increases by one count every 128 μs, and the register rolls over every 32.768 ms. The SPI master can periodically read the COUNT register, and verify the difference between subsequent register reads against the system time base. 1. The SPI access rates and deviations must be taken into account for this oscillator verification method. 3.4.2 CRC Based Clock Monitor The device includes unique DSP cores for the X-Axis and Y-Axis. Each DSP core uses multiple frequencies derived from the oscillator, ranging from the base oscillator frequency to the base oscillator frequency divided by 256. In order to guarantee that the clocks for the two DSP cores are synchronized, a clock CRC monitor is employed. The CRC monitor is updated every cycle of the base oscillator. 3.5 Transducer The transducer is an overdamped mass-spring-damper system described by the following transfer function: 2 ωn H ( s ) = -----------------------------------------------------2 2 s + 2 ⋅ ξ ⋅ ωn ⋅ s + ωn where: ζ= Damping Ratio ωn= Natural Frequency = 2∗Π∗fn Reference Section 2.4 for transducer parameters. MMA65xx Sensor Freescale Semiconductor, Inc. 23 3.6 Self Test Interface When self test is enabled, the self test interface applies a voltage to the g-cell, causing a deflection of the proof mass. Once enabled, offset cancellation is suspended and the deflection results in an acceleration which is superimposed upon the input acceleration. The resulting acceleration readings can be compared either against absolute limits, or the values stored in the Self Test Deflection Registers (Reference Section 3.1.2). The self test interface is controlled through SPI write operations to the DEVCFG_X and DEVCFG_Y registers described in Section 3.1.7 only if the ENDINIT bit in the DEVCFG register is cleared. A diagram of the self test interface is shown in Figure 10. ST_Y ENDINIT Y-AXIS g-CELL SELF TEST VOLTAGE GENERATOR ENDINIT X-AXIS g-CELL ENDINIT ST_X Figure 10. Self Test Interface 3.6.1 Raw Self Test Deflection Verification The raw self test deflection can be directly verified against raw self test limits listed in Section 2.4. 3.6.2 Delta Self Test Deflection Verification The raw self test deflection can be verified against the ambient temperature self test deflection value recorded at the time the device was produced. The production self test deflection is stored in the STDEFL_X and STDDEFL_Y registers such that the minimum stored value (0x00) is equivalent to ΔSTMIN, and the maximum stored value (0xFF) is equivalent to ΔSTMAX. The Delta Self Test Deflection limits can then be determined by the following equations: ΔSTDEFLx CNTS ΔST ACCMINLIMIT = FLOOR ⋅ ⎛⎝ ΔST MIN + ------------------------------------------ × [ ΔST MAX – ΔST MIN ]⎞⎠ × ( 1 – ΔST ACC ) 255 ΔSTDEFLx CNTS ΔST ACCMAXLIMIT = CEIL ⋅ ⎛⎝ ΔST MIN + ------------------------------------------ × [ ΔST MAX – ΔST MIN ]⎞⎠ × ( 1 + ΔST ACC ) 255 where: ΔSTACC ΔSTDEFLxCNTS The accuracy of the self test deflection relative to the stored deflection as specified in Section 2.4. The value stored in the STDEFL_X or STDEFL_Y register. ΔSTMIN The minimum self test deflection at 25C as specified in Section 2.4. ΔSTMAX The maximum self test deflection at 25C as specified in Section 2.4. MMA65xx 24 Sensor Freescale Semiconductor, Inc. ΣΔ Converter 3.7 A sigma delta converter provides the interface between the transducer and the DSP. The output of the ΣΔ converter is a data stream at a nominal frequency of 1 MHz. g-CELL α1= CTOP VX FIRST INTEGRATOR CINT1 z-1 SECOND INTEGRATOR α2 z-1 1 - z-1 CBOT 1-BIT QUANTIZER ΣΔ_OUT 1 - z-1 ADC ΔC = CTOP - CBOT β1 β2 V = ΔC x VX / CINT1 V = ±2 × VREF DAC Figure 11. ΣΔ Converter Block Diagram 3.8 Digital Signal Processing Block A digital signal processing (DSP) block is used to perform signal filtering and compensation operations. A diagram illustrating the signal processing flow is shown in Figure 12. Arm/PCM Output Section 3.8.9 Section 3.8.10 A ΣΔ_OUT SINC Filter Section 3.8.2 B Low Pass Filter Section 3.8.3 C Compensation D Section 3.8.6 Interpolation Section 3.8.7 E Offset Cancellation Section 3.8.4 F Offset Cancellation Output Scaling Raw Output Scaling I To ARM_x G To SPI H To SPI Figure 12. Signal Chain Diagram Table 26. Signal Chain Characteristics Description Sample Data Width Over Range Time (μs) Bits Bits Effective Bits Rounding Resolution Bits Typical Block Latency Reference A SD 1 1 1 3.2μs Section 3.7 B SINC Filter 8 14 13 11.2μs Section 3.8.2 C Low Pass Filter 8/16 20 4 12 4 Reference Section 3.8.3 Section 3.8.3 D Compensation 8/16 20 4 12 4 7.875μs Section 3.8.6 E Interpolation 4/8 20 4 12 4 ts / 2 Section 3.8.8 F Offset Cancellation 256 20 4 12 4 N/A Section 3.8.4 GH SPI Output 4/8 — — 12 — ts / 2 I PCM Output 4/8 — — 9 — Section 3.8.11 MMA65xx Sensor Freescale Semiconductor, Inc. 25 3.8.1 DSP Clock The DSP is clocked at 8 MHz, with an effective 6MHz operating frequency. The clock to the DSP is disabled for 1 clock prior to each edge of the ΣΔ modulator clock to minimize noise during data conversion. 8 MHz OSC 6 MHz Digital 1MHz Modulator Figure 13. Clock Generation 3.8.2 Decimation Sinc Filter The serial data stream produced by the ΣΔ converter is decimated and converted to parallel values by a 3rd order 16:1 sinc filter with a decimation factor of 8 or 16, depending on the Low Pass Filter selected. 3 1 – z – 16 H ( z ) = ----------------------------------16 × ( 1 – z – 1 ) Figure 14. Sinc Filter Response, tS = 8 μs 3.8.3 Low Pass Filter Data from the Sinc filter is processed by an infinite impulse response (IIR) low pass filter. . n0 + ( n1 ⋅ z –1 ) + ( n2 ⋅ z –2 ) + ( n3 ⋅ z –3 ) + ( n4 ⋅ z –4 ) H ( z ) = --------------------------------------------------------------------------------------------------------------------------------d0 + ( d1 ⋅ z –1 ) + ( d2 ⋅ z –2 ) + ( d3 ⋅ z –3 ) + ( d4 ⋅ z –4 ) The device provides the option for one of twelve low-pass filters. The filter is selected independently for each axis with the LPF_X[3:0] and LPF_Y[3:0] bits in the DEVCFG_X and DEVCFG_Y registers. The filter selection options are listed in Section 3.1.7.3, Table 11. Response parameters for the low-pass filter are specified in Section 2.4. Filter characteristics are illustrated in the figures on the following pages. MMA65xx 26 Sensor Freescale Semiconductor, Inc. Table 27. Low Pass Filter Coefficients LPF_X/ Description Filter LPF_Y Filter -3dB Frequency Number Value Order (±5%) (HEX) 8 0 9 1 10 2 13 5 11 3 12 4 0x08 0x00 0x09 0x01 0x0A 0x02 0x0D 0x05 0x0B 0x03 0x0C 0x04 50 Hz LPF 100 Hz LPF 150 Hz LPF 300 Hz LPF 200 Hz LPF 400 Hz LPF 200 Hz LPF 400 Hz LPF 400 Hz LPF 800 Hz LPF 500 Hz LPF 1000 Hz LPF 4 4 4 4 4 4 3 3 4 4 4 4 Sample Time (μs ±5%) 16 8 16 8 16 8 16 8 16 8 16 8 Group Delay Filter Coefficients n0 2.08729034056887e-10 d0 1 n1 8.349134489240434e-10 d1 -3.976249694824219 n2 1.25237777794924e-09 d2 5.929003009577855 n3 8.349103355433541e-10 d3 -3.929255528257727 n4 2.087307211059861e-10 d4 0.9765022168437554 n0 1.639127731323242e-08 d0 1 n1 6.556510925292969e-08 d1 -3.928921222686768 Self Test Step Response (ms) 14.00 26816/ fosc 7.00 n2 9.834768482194806e-08 d2 5.789028996785419 n3 6.556510372902331e-08 d3 -3.791257019240902 n4 1.639128257923422e-08 d4 0.9311495074496179 n0 5.124509334564209e-08 d0 1 n1 2.049803733825684e-07 d1 -3.905343055725098 6.00 9024/ fosc 3.00 n2 3.074705789151505e-07 d2 5.72004239520561 n3 2.049803958150164e-07 d3 -3.723967810019985 n4 5.124510693742625e-08 d4 0.9092692903507213 n0 2.720393240451813e-06 d0 1 n1 8.161179721355438e-06 d1 -2.931681632995605 5.00 6784/ fosc 2.50 n2 8.161180123840722e-06 d2 2.865296718275204 n3 2.720393634345496e-06 d3 -0.9335933215174919 n4 0 d4 0 n0 7.822513580322266e-07 d0 1 n1 3.129005432128906e-06 d1 -3.811614513397217 n2 4.693508163398543e-06 d2 5.450666051045118 n3 3.129005428784364e-06 d3 -3.465805771100349 n4 7.822513604678875e-07 d4 0.8267667478030489 n0 1.865386962890625e-06 d0 1 n1 7.4615478515625e-06 d1 -3.765105724334717 4.80 5632/ fosc 2.40 2.50 3392/ fosc 1.70 n2 1.119232176112846e-05 d2 5.319861050818872 n3 7.4615478515625e-06 d3 -3.34309015036024 n4 1.865386966264658e-06 d4 0.7883646729233078 3.20 2688/ fosc 1.60 Note: Low Pass Filter figures do not include g-cell frequency response. MMA65xx Sensor Freescale Semiconductor, Inc. 27 Figure 15. Low-Pass Filter Characteristics: fC = 100 Hz, Poles = 4, tS = 8 μs MMA65xx 28 Sensor Freescale Semiconductor, Inc. Figure 16. Low-Pass Filter Characteristics: fC = 300 Hz, Poles = 4, tS = 8 μs MMA65xx Sensor Freescale Semiconductor, Inc. 29 Figure 17. Low-Pass Filter Characteristics: fC = 400 Hz, Poles = 4, tS = 8 μs MMA65xx 30 Sensor Freescale Semiconductor, Inc. Figure 18. Low-Pass Filter Characteristics: fC = 400 Hz, Poles = 3, tS = 8 μs MMA65xx Sensor Freescale Semiconductor, Inc. 31 Figure 19. Low-Pass Filter Characteristics: fC = 800 Hz, Poles = 4, tS = 8 μs MMA65xx 32 Sensor Freescale Semiconductor, Inc. Figure 20. Low-Pass Filter Characteristics: fC = 1000 Hz, Poles = 4, tS = 8 μs MMA65xx Sensor Freescale Semiconductor, Inc. 33 3.8.4 Offset Cancellation The device provides the option to read offset cancelled acceleration data via the SPI by clearing the OC bit in the DEVCFG register (reference Section 3.1.6.1) and in the SPI command (reference Section 4.1). A block diagram of the offset cancellation is shown in Figure 21, and response parameters are specified in Section 2.4 and in Table 28. Downsampled to 256μs LPFOUT T Registers updated every 1.049s Accumulator Shift 4096 samples T1 T2 T3 T4 OFFTHRNEG T5 T6 OFF_ERR 1.049s OFF_ERR OFFTHRPOS Updated every 1.049s 1/8 LSB Increment 1/4 LSB 6.291s Average Offset Inc/Dec Decrement 1/4 LSB 1/8 LSB OFFCORRP OFF_CORR_VALUE OCOUT OFFCORRN Alignment Correction Figure 21. Offset Cancellation Block Diagram In normal operation, the offset cancellation circuit computes a 24,576 sample running average of the acceleration data downsampled to 256 μs. The running average is compared against positive and negative thresholds to determine the offset correction value that will be applied to the acceleration data. During start up, three phases of moving average sizes are used to allow for faster convergence of misuse input signals. Reference Table 28 for offset cancellation timing information during startup and normal operation. The offset cancellation startup phase can also be directly controlled during initialization (ENDINIT = ‘0’) using the OCPHASE[1:0] bits and the OFFCFG_EN bit in the DEVCTL register, as described in Section 3.1.5.2 and Section 3.1.5.3. Table 28. Offset Cancellation Timing Specifications Phase Start Time of Phase (from POR) Typical # of Samples in Time in Phase Phase (ms) Samples Averaged OFF_CORR_VALUE Update Rate (ms) Averaging Period (ms) Maximum Slew Rate (LSB/s) Averaging Filter -3dB Frequency (Hz) Start 1 tOP 524.288 2048 48 2.048 12.288 122.1 36.05 Start 2 tOP + 524.288 524.288 2048 384 16.38 98.304 15.26 4.506 Start 3 tOP + 1048.576 524.288 2048 3072 131.1 786.432 1.907 0.5632 Normal tOP + 1572.864 — — 24576 1049 6291.456 0.2384 0.07040 When the self test circuitry is active, the offset cancellation block and the offset monitor block are suspended, and the offset correction value is constant. Once the self test circuitry is disabled, the offset cancellation block remains suspended for the time tST_OMB to allow the acceleration output to return to it’s nominal offset. 3.8.5 Offset Monitor The device provides the option for an offset monitor circuit. The offset monitor circuit is enabled when the OFMON bit in the DEVCFG register is programmed to a logic ‘1’. The output of the offset cancellation circuit is compared against a high and low threshold. If the offset correction value exceeds either the OFFTHRPOS, or OFFTHRNEG threshold, an Offset Over Range Error condition is indicated. The offset correction value update rate is listed in Table 28: “Maximum Slew Rate”. Because the offset monitor uses this value, the offset monitor will also update at this rate. The time to indicate an Offset Over Range Error is dependent upon the input signal. The offset monitor status remains suspended during self test, because the offset monitor is based on the offset cancellation circuit, which is also suspended during self test. The offset monitor is disabled for 2.1 seconds following reset regardless of the state of the OFMON bit. MMA65xx 34 Sensor Freescale Semiconductor, Inc. 3.8.6 Signal Compensation The device includes internal OTP and signal processing to compensate for sensitivity error and offset error. This compensation is necessary to achieve the specified parameters in Section 2.4. 3.8.7 Output Scaling The 20 bit digital output from the DSP is clipped and scaled to a 12-bit data word which spans the acceleration range of the device. Figure 22 shows the method used to establish the output acceleration data word from the DSP output. Over Range Signal D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 12-Bit Data Word D15 D14 D13 D12 D11 D10 D9 Noise D8 D7 D6 D5 D4 D8 D7 D6 D5 D4 D3 D2 D1 D0 Using Rounding Figure 22. 12-Bit Output Scaling Diagram 3.8.8 Data Interpolation The device includes 2 to 1 data interpolation to minimize the system sample jitter. Each result produced by the digital signal processing chain is delayed one half of a sample time, and the interpolated value of successive samples is provided between sample times. This operation is illustrated below. Sn-3 Sn-2 Sn-1 Sn Internal Sample Rate t ts ts Sn-3 Sn – 3 + Sn – 2 ------------------------------2 Sn-2 ts Sn – 2 + Sn – 1 ------------------------------2 Sn-1 Sn – 1 + Sn ----------------------2 Output Sample Rate t SPI acceleration request occurring in this window receives interpolated sample SPI acceleration request occurring in this window receives true sample. Figure 23. Data Interpolation Timing MMA65xx Sensor Freescale Semiconductor, Inc. 35 The effect of this interpolation at the system level is a 50% reduction in sample jitter. Figure 24 shows the resulting output data for an input signal. 80 75 Internally Sampled Values 70 Counts 65 60 Fixed Latency: tS / 2 Earliest Transmission Point of Interpolated Values 55 Earliest Transmission Point of Internally Sampled Values 50 45 Window of Transmission for Interpolated Values (Maximum: tS / 2) Window of Transmission for = Signal Jitter = Sampled Values (Maximum: tS / 2) 40 0 5 10 15 Input Signal Internally Sampled Signal Interpolated Samples 20 25 30 35 40 Time Figure 24. Data Interpolation Example 3.8.9 Acceleration Data Timing The SPI uses a request/response protocol, where a SPI transfer is completed through a sequence of 2 phases. Reference Section 4 for more details regarding the SPI protocol. The device latches the associated data for an acceleration request at the rising edge of CS. The most recent sample available from the DSP (including interpolation) is latched, and transmitted during the subsequent SPI transfer. SCLK CS MOSI Request X-Axis Request Y-Axis Request X-Axis Request Y-Axis X-Axis Response Y-Axis Response X-Axis Response MISO X-Axis Data Latched X-Axis Arm Function updated Y-Axis Data Latched Y-Axis Arm Function updated if applicable Figure 25. Acceleration Data Timing MMA65xx 36 Sensor Freescale Semiconductor, Inc. 3.8.10 ARMING FUNCTION The device provides the option for an arming function with 3 modes of operation. The operation of the arming function is selected by the state of the A_CFG bits in the DEVCFG register. Reference Section 4.5 for the operation of the Arming function with exception conditions. Error conditions do not impact prior arming function responses. If an error occurs after an arming activation, the corresponding pulse stretch for the existing arming condition will continue. However, new acceleration reads will not update the arming function regardless of the acceleration value. 3.8.10.1 Arming Function: Moving Average Mode In moving average mode, the arming function runs a moving average on the offset cancelled output of each acceleration axis. The number of samples used for the moving average (k) is programmable via the AWS_Xx[1:0] and ARM_Yx[1:0] bits in the ARMCFGX and ARMCFGY registers. Reference Section 3.1.8 for register details. ARM_MAn = (OCn + OCn-1 + ... + OCn+1-k)/k Where n is the current sample. The sample rate for each axis is determined by the SPI acceleration data sample rate. At the rising edge of CS for an acceleration data SPI request, the moving average for the associated axis is updated with a new sample. Reference Figure 28. The SPI acceleration data sample rate must meet the minimum time between requests (tACC_REQ_x) specified in Section 2.6. The moving average output is compared against positive and negative 8-bit thresholds that are individually programmed for each axis via the ARMT_Xx and ARMT_Yx registers. Reference Section 3.1.10 for register details. If the moving average equals or exceeds either threshold, an arming condition is indicated, the ARM_X or ARM_Y output is asserted for the associated axis, and the pulse stretch counter is set as described in Section 3.8.10.4. The ARM_X or ARM_Y output is de-asserted only when the pulse stretch counter expires. Figure 28 shows the arming output operation for different SPI conditions. ARMT_xP[7:0] AWS_xP[1:0] Positive Moving Average Offset Cancellation Pulse Stretch OffCanc_ARM_x[10:0] AWS_xN[1:0] Gating I/O ARM_x Negative Moving Average ARMT_xN[7:0] APS_x[1:0] Figure 26. Arming Function Block Diagram - Moving Average Mode The moving average window size must be set prior to setting the arming function to moving average mode, or prior to requesting acceleration data via the SPI. If the moving average window size is changed after enabling moving average mode, the arming function must first be disabled by setting the A_CFG bits to “000”. Once the desired moving average window size is set, the moving average mode can be re-enabled. MMA65xx Sensor Freescale Semiconductor, Inc. 37 3.8.10.2 Arming Function: Count Mode In count mode, the arming function compares each offset cancelled sample against positive and negative thresholds that are individually programmed for each axis via the ARMT_Xx and ARMT_Yx registers. Reference Section 3.1.10 for register details. If the sample equals or exceeds either threshold, a sample counter is incremented. If the sample does not exceed either threshold, the sample counter is reset to zero. The sample rate for each axis is determined by the SPI acceleration data sample rate. At the rising edge of CS for an acceleration data SPI request, a new sample for the associated axis is compared against the thresholds. Reference Figure 28. The SPI acceleration data sample rate must meet the minimum time between requests (tACC_REQ_x) specified in Section 2.6. A sample count limit is programmable via the AWS_Xx[1:0] and AWS_Yx[1:0] bits in the ARMCFGX and ARMCFGY registers. If the sample count reaches the programmable sample count limit, an arming condition is indicated, the ARM_X or ARM_Y output is asserted for the associated axis, and the pulse stretch counter is set as described in Section 3.8.10.4. The ARM_X or ARM_Y output is de-asserted only when the pulse stretch counter expires. Figure 28 shows the arming output operation for different SPI conditions. AWS_xP[1:0] ARMT_xP[7:0] Offset Cancellation 1-4 Sample Pulse Stretch Counter OffCanc_ARM_x[10:0] Gating I/O ARM_x ARMT_xN[7:0] APS_x[1:0] Figure 27. Arming Function Block Diagram - Count Mode SCLK CS MOSI Request X-Axis Request Y-Axis Request X-Axis Request Y-Axis Y-Axis Response X-Axis Response Y-Axis Response X-Axis Response Y-Axis Arm Condition Not Present X-Axis Arm Condition Present Y-Axis Arm Condition Present X-Axis Arm Condition Not Present MISO ARM_X ARM_Y X-Axis Data Latched for Arm & SPI Y-Axis Data Latched for Arm & SPI X-Axis Data Latched for Arm & SPI Y-Axis Pulse Stretch tARM X-Axis Pulse Stretch Figure 28. X and Y Axis Arming Conditions, Moving Average and Count Mode MMA65xx 38 Sensor Freescale Semiconductor, Inc. 3.8.10.3 Arming Function: Unfiltered Mode On the rising edge of CS for an acceleration request, the most recent available offset cancelled sample for the requested axis is compared against positive and negative thresholds that are individually programmed for each axis via the ARMT_Xx and ARMT_Yx registers. Reference Section 3.1.10 for register details. If the sample equals or exceeds either threshold, an arming condition is indicated. Once an arming condition is indicated for the X-Axis, the ARM_X output is asserted when CS is asserted and the MISO data includes an acceleration response for that axis. Once an arming condition is indicated for the Y-Axis, the ARM_Y output is asserted when CS is asserted and the MISO data includes an acceleration response for that axis. The pulse stretch function is not applied in Unfiltered mode. Figure 29 contains a block diagram of the Arming Function operation in Unfiltered Mode. Figure 30 shows the Arming output operation under the different SPI request conditions. ACFG[2] ACFG[1] CS I/O AXIS Select ARM_x ARMING FUNCTION Interpolated Sample Rate Figure 29. Arming Function Block Diagram - Unfiltered Mode SCLK CS MOSI Request X-Axis Request Y-Axis Request X-Axis Request Y-Axis Y-Axis Response X-Axis Response Y-Axis Response X-Axis Response Y-Axis Arm Condition Not Present X-Axis Arm Condition Present Y-Axis Arm Condition Present X-Axis Arm Condition Not Present MISO ARM_X ARM_Y Y-Axis Data Latched for Arm & SPI X-Axis Data Latched for Arm & SPI tARM_UF_DLY tARM_UF_ASSERT X-Axis Data Latched for Arm & SPI tARM_UF_DLY tARM_UF_ASSERT Figure 30. X and Y Axis Arming Conditions, Unfiltered Mode MMA65xx Sensor Freescale Semiconductor, Inc. 39 3.8.10.4 Arming Pulse Stretch Function A pulse stretch function can be applied to the arming outputs in moving average mode, or count mode. If the pulse stretch function is not used (APS_X[1:0] = ‘00’ or APS_Y[1:0] = ‘00’), the arming output is asserted if and only if an arming condition exists for the associated axis after the most recent evaluated sample. The arming output is de-asserted if and only if an arming condition does not exist for the associated axis after the most recent evaluated sample. If the pulse stretch function is used, (APS_X[1:0] not equal ‘00’ or APS_Y[1:0] not equal ‘00’), the arming output is controlled only by the value of the pulse stretch timer value. If the pulse stretch timer value is non-zero, the arming output is asserted. If the pulse stretch timer is zero, the arming output is de-asserted. The pulse stretch counter continuously decrements until it reaches zero. The pulse stretch counter is reset to the programmed pulse stretch value if and only if an arming condition exists for the associated axis after the most recent evaluated sample. Reference Figure 28. The desired pulse stretch time is individually programmable for each axis via the APS_X[1:0] and APS_Y[1:0] bits in the ARMCFG register. Exception conditions listed in Section 4.5 do not impact prior arming function responses. If an exception occurs after an arming activation, the corresponding pulse stretch for the existing arming condition will continue. However, new acceleration reads will not reset the pulse stretch counter regardless of the acceleration value. 3.8.10.5 Arming Pin Output Structure The arming output pin structure can be set to active high, or active low with the A_CFG bits in the DEVCFG register as described in Section 3.1.6.6. The active high and active low pin output structures are shown in Figure 31. Open Drain, Active High Open Drain, Active Low VCC Arm Function Gating VCC ARM_x ARM_x Arm Function Gating Figure 31. Arming Function - Pin Output Structure MMA65xx 40 Sensor Freescale Semiconductor, Inc. 3.8.11 PCM Output Function The device provides the option for a PCM output function. The PCM output is enabled by setting the A_CFG bits in the DEVCFG register to the appropriate state as described in Section 3.1.6.6. Selecting the PCM output enables the following functions: • The PCM_X and PCM_Y pins are programmed as a digital outputs. Reference Section 2.3 for the pin electrical parameters. • The acceleration value output from the offset cancellation block is saturated to 9-bits and converted to an unsigned value. Note, the 9-bit unsigned acceleration value uses the full range of values (0 - 511). • The 9-bit acceleration value is input into a summer clocked at 8MHz. • The carry from the summer circuit is output to the PCM pin. A block diagram of the PCM output is shown in Figure 32. Exception conditions affect the PCM output as listed in Section 4.5. Output Scaling 9 A CARRY ARM_x/PCM_x OC_x[9:1] 9 Bit ADDER 9 Sample updated every 8μS B SUM fCLK = 8 MHz D D Q Q Q D Q D Q FF D Q FFD Q FFD Q FFD Q FF CLK Q FFFF CLK Q FF CLK Q FF CLK Q CLK Q CLK Q CLK Q CLK Q CLK Q D 9 Figure 32. PCM Output Function Block Diagram MMA65xx Sensor Freescale Semiconductor, Inc. 41 3.9 Serial Peripheral Interface The device includes a Serial Peripheral Interface (SPI) to provide access to the configuration registers and digital data. Reference Section 4 for details regarding the SPI protocol and available commands. To maximize independence between the X and Y channels, the device includes two interface blocks, one for each axis. The X-axis interface block responds only to X-axis acceleration requests, or even addressed register commands. The Y-axis interface block responds only to Y-axis acceleration requests, or odd addressed register commands. To the SPI master, the device operates as a single device. The internal independent blocks are transparent. Each SPI block has an independent shift register. Once a message is received (rising edge of CS), the contents of the two shift registers are compared. If the contents do not match, the Y-Axis SPI block will not respond, and the X-Axis SPI block will respond with a SPI Error as shown in Table 30. If the contents match, each SPI block decodes the message, and the appropriate block enables DO for a response during the next SPI message. Figure 33 shows an internal diagram of the SPI. Registers X SPI If Bit 13 == ‘1’ If Bit 13 = ‘0’ & Bit 14 == ‘0’ & A0 == ‘0’ SPI Master Even Address Regs X SPI Shift Register X-Axis Raw Data X-Axis OC Data CS_M SPI Mismatch Error (SPI Error) CS CS SCLKM SCLK SCLK MOSIM MOSI MOSI MISOM MISO MISO I/O Odd Address Regs Y SPI Shift Register Y-Axis Raw Data Y-Axis OC Data Y SPI If Bit 13 == ‘1’ If Bit 13 = ‘0’ & Bit 14 == ‘1’ & A0 == ‘1’ Figure 33. SPI Diagram MMA65xx 42 Sensor Freescale Semiconductor, Inc. 3.10 Device Initialization Following power-up, under-voltage reset, or a SPI reset command sequence, the device proceeds through an internal initialization process as shown below. Figure 34 also shows the device performance for an example external system level initialization procedure. Internal Initialization OTP Copy to Offset Cancellation Offset Cancellation Offset Cancellation Offset Cancellation Mirror Registers Startup Phase 1 Startup Phase 2 Startup Phase 3 Normal Mode tOC_PHASE1 tOC_PHASE2 tOC_PHASE3 External Initialization Delay Read DEVSTAT Verify X-Axis to clear flags Self Test & Verify X-Axis Re-read DEVSTAT ARM_X Asserted to verify Status Dly Dly Offset Verify Y-Axis Initialize R/W Offset & ARM_Y Registers to DeAsserted Desired State Dly Re-Initialize Verify X-Axis Offset & ARM_X R/W Registers Normal DeAsserted (if needed) Dly Mode Verify Y-Axis Verify Y-Axis and Self Test & Offset & ARM_Y Set ENDINIT ARM_Y Asserted DeAsserted Verify X-Axis Offset & ARM_X DeAsserted tSTRISE tOP X_ST Assertion Dependent on Arming Mode X_ARM DeAssertion Dependent on Pulse Stretch and/or Arming Mode tST_OMB Y_ST tSTFALL Assertion Dependent on Arming Mode Y_ARM POR Ready for SPI Command ENDINIT Clear Internal Offset Error Corrected to ‘0’ Activate X-Axis Self Test DeActivate X-Axis Self Test Activate Y-Axis Self Test DeAssertion Dependent on Pulse Stretch and/or Arming Mode DeActivate Y-Axis Self Test Notes:1) X-Axis and Y-Axis Self Test can be enabled and evaluated simultaneously to reduce test time. For failure mode coverage of the arming pins and of potential common axis failures, Freescale recommends independent self test activation. 2) tSTRISE and tSTFALL are dependent on the selected LPF group delay. Figure 34. Initialization Process MMA65xx Sensor Freescale Semiconductor, Inc. 43 3.11 Overload Response 3.11.1 Overload Performance The device is designed to operate within a specified range. Acceleration beyond that range (overload) impacts the output of the sensor. Acceleration beyond the range of the device can generate a DC shift at the output of the device that is dependent upon the overload frequency and amplitude. The g-cell is overdamped, providing the optimal design for overload performance. However, the performance of the device during an overload condition is affected by many other parameters, including: • g-cell damping • Non-linearity • Clipping limits • Symmetry Figure 35 shows the g-cell, ADC and output clipping of the device over frequency. The relevant parameters are specified in Section 2.1, and Section 2.7. g-cellRolloff Acceleration (g) Region Clipped by Output LPFRolloff ion Reg b ped Clip y g- cell Determined by g-cell roll-off and ADC clipping o ue t ADC on d earity i t y r b o t in ed l Dis on-L lipp igna and N nC S o i f g o Re etry ion Reg Asymm gg-cell_Clip gADC_Clip Determined by g-cell roll-off and full scale range gRange_Norm Region of Interest fLPF Region of No Signal Distortion Beyond Specification fg-Cell 5kHz 10kHz Frequency (kHz) Figure 35. Output Clipping Vs. Frequency 3.11.2 Sigma Delta Over Range Response Over range conditions exist when the signal level is beyond the full-scale range of the device but within the computational limits of the DSP. The ΣΔ converter can saturate at levels above those specified in Section 2.1 (GADC_CLIP). The DSP operates predictably under all cases of over range, although the signal may include residual high frequency components for some time after returning to the normal range of operation due to non-linear effects of the sensor. MMA65xx 44 Sensor Freescale Semiconductor, Inc. 4 SPI Communications Communication with the device is completed through synchronous serial transfers via SPI. The device is a slave device configured for CPOL = 0, CPHA = 0, MSB first. SPI transfers are completed through a sequence of two phases. During the first phase, the type of transfer and associated control information is transmitted from the SPI master to the device. Data from the device is transmitted during the second phase. Any activity on MOSI or SCLK is ignored when CS is negated. Consequently, intermediate transfers involving other SPI devices may occur between phase one and phase two. Reference Figure 36. SCLK CS MOSI Phase One: Command Phase Two: Response Phase One: Response -Previous Command MISO SCLK CS MOSI T1P1 T2P1 T3P1 T1P2 T2P2 T3P2 MISO Figure 36. SPI Transfer Detail MMA65xx Sensor Freescale Semiconductor, Inc. 45 4.1 SPI Command Format Commands are transferred from the SPI master to the device. Valid commands fall into two categories: register operations, and acceleration data requests. Table 29. SPI Command Message Summary MSB LSB 15 14 0 AX 13 12 11 10 9 8 7 6 5 4 3 2 1 0 A OC 0 0 0 0 0 0 0 0 1 SD ARM P Command Type Reference AX= Axis Selection 0 X-Axis Acceleration Data 1 Y-Axis Acceleration Data A = Acceleration Data Request 0 1 Register Operation Acceleration Data Request OC = Offset Cancelled Data Confirmation 0 Offset Cancelled Data Enabled 1 Raw Acceleration Data Enabled SD = Signed Data Confirmation Signed Data Enabled 0 Unsigned Data Enabled 1 ARM = ARM Function Status Confirmation Disabled / PCM Output Enabled 0 Arming Function Enabled 1 P = Odd Parity 0 AX A OC 0 0 0 0 0 0 0 0 0 SD ARM P Accel Data 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 1 X-Axis OC, Signed, Disabled/PCM 0 0 1 0 0 0 0 0 0 0 0 0 1 0 1 0 X-Axis OC, Signed, ARM Enabled 0 0 1 0 0 0 0 0 0 0 0 0 1 1 0 0 X-Axis OC, Unsigned, Disabled/PCM 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 1 X-Axis OC, Unsigned, ARM Enabled 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 X-Axis Raw, Signed, Disabled/PCM 0 0 1 1 0 0 0 0 0 0 0 0 1 0 1 1 X-Axis Raw, Signed, ARM Enabled 0 0 1 1 0 0 0 0 0 0 0 0 1 1 0 1 X-Axis Raw, Unsigned, Disabled/PCM 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 0 X-Axis Raw, Unsigned, ARM Enabled 0 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 Y-Axis OC, Signed, Disabled/PCM 0 1 1 0 0 0 0 0 0 0 0 0 1 0 1 1 Y-Axis OC, Signed, ARM Enabled 0 1 1 0 0 0 0 0 0 0 0 0 1 1 0 1 Y-Axis OC, Unsigned, Disabled/PCM 0 1 1 0 0 0 0 0 0 0 0 0 1 1 1 0 Y-Axis OC, Unsigned, ARM Enabled 0 1 1 1 0 0 0 0 0 0 0 0 1 0 0 1 Y-Axis Raw, Signed, Disabled/PCM 0 1 1 1 0 0 0 0 0 0 0 0 1 0 1 0 Y-Axis Raw, Signed, ARM Enabled 0 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0 Y-Axis Raw, Unsigned, Disabled/PCM 0 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 Y-Axis Raw, Unsigned, ARM Enabled P AX A D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Command Type Reference A3 A2 A1 A0 P 0 0 0 0 0 0 0 0 0 0 Register Read Section 4.4 D7 D6 D5 D4 D3 D2 D1 D0 Register Write Section 4.4 A4 Register Address A4 P 1 A3 A2 A1 A0 0 Register Address Data to be Written to Register P = Odd Parity MMA65xx 46 Sensor Freescale Semiconductor, Inc. 4.2 SPI Response Format Table 30. SPI Response Message Summary MSB LSB 15 14 13 12 11 D15 D14 AX P D11 D1 D0 10 9 8 7 6 5 4 3 2 1 0 Response to Valid Acceleration Request CMD A AX Reference D10 Acceleration D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D5 D4 D3 D2 AX = Axis Requested 0 X-Axis Acceleration Response 1 Y-Axis Acceleration Response P = Odd Parity S[1:0] = Device Status CMD Valid Accel Request D1 D0 0 0 In Initialization (ENDINIT = ‘0’) 0 1 Normal Request 1 0 ST Active 1 1 Internal Error Present / SPI Error A AX AX P S1 S0 1 0 Accel Data 0 P 0 1 D11 D10 D9 X- Axis Acceleration Data D8 D7 D6 1 0 Accel Data 0 P 1 0 X- Axis Self Test Active Acceleration Data 1 0 Accel Data 0 P 0 0 X- Axis Acceleration Data, Initialization in Process (ENDINIT=’0’) 1 1 Accel Data 1 P 0 1 Y-Axis Acceleration Data 1 1 Accel Data 1 P 1 0 Y-Axis Self Test Active Acceleration Data 1 1 Accel Data 1 P 0 0 Y- Axis Acceleration Data, Initialization in Process (ENDINIT=’0’) Reference Section 4.3 MSB 15 LSB 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Response to Valid Register Access CMD Register Write A 0 AX 1 Reference D15 D14 AX P D11 D10 D9 D8 0 0 1 P 1 1 1 0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 Section 4.4.1 New Contents of Register D7 Register Read 0 0 0 1 0 P 1 1 1 D6 D5 D4 D3 D2 D1 D0 0 Section 4.4.2 Contents of Register MSB 15 LSB 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Error Responses CMD Invalid Accel Request A x AX Reference D15 D14 AX P D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 0 0 AX P 1 1 0 0 0 0 0 0 0 0 0 0 x Internal Error Present x x MISO Error x x Section 4.3 Section 4.5.5 Section 4.5.2 0 0 0 P 1 1 0 0 0 0 0 0 0 0 0 0 SPI Error x x Invalid Register Request Section 4.5.1 0 x 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 Section 4.4 Self Test Error 0 x 0 0 AX P 1 1 0 0 0 0 0 0 0 0 0 0 Section 4.5.5 MMA65xx Sensor Freescale Semiconductor, Inc. 47 4.3 Acceleration Data Transfers Twelve bit Acceleration data requests are initiated when the Acceleration bit of the SPI command message (A) is set to a logic ‘1’, and bit D[3] of the SPI command message is set to a logic ‘1’. The Axis Selection bit (AX) selects the type of acceleration data requested, as shown in Table 31. Table 31. Acceleration Data Request Axis Selection Bit (AX) Data Type 0 X-Axis Acceleration Data 1 Y-Axis Acceleration Data To verify that the device is configured as expected, each acceleration data request includes the configuration information which impacts the output data. The requested configuration is compared against the data programmed in the writable register block. Details are shown in Table 32. Table 32. Acceleration Data Request Configuration Information Programmable Option Command Message Bit Writable Register Information Raw or Offset Cancelled Data OC DEVCFG[7] (OC) Signed or Unsigned Data SD DEVCFG[4] (SD) Arming Function or PCM Output ARM DEVCFG[2] || DEVCFG[1] (A_CFG[2] || A_CFG[1]) If the data listed in Table 32 does not does not match, an Acceleration Data Request Mismatch failure is detected and no acceleration data is transmitted. Reference Section 4.5.3.1. Acceleration data request commands include a parity bit (P). Odd parity is employed. The number of logic ‘1’ bits in the acceleration data request command must be an odd number. Acceleration data is transmitted on the next SPI message if and only if all of the following conditions are met: • The DEVINIT bit in the DEVSTAT register is not set • The DEVRES bit in the DEVSTAT register is not set • The IDE bit in the DEVSTAT register is not set (Reference Section 4.5.5) • No SPI Error is detected (Reference Section 4.5.1) • No MISO Error is detected (Reference Section 4.5.2) • No Acceleration Data Request Mismatch failure is detected (Reference Section 4.5.3.1) • No Self Test Error is present (reference Section 4.5.5.2) • No Offset Monitor Error is present for the requested channel (reference Section 4.5.6) If the above conditions are met, the device responds with a “valid acceleration data request” response as shown in Table 30. Otherwise, the device responds as specified in Section 4.5. MMA65xx 48 Sensor Freescale Semiconductor, Inc. 4.4 Register Access Operations Two types of register access operations are supported; register write, and register read. Register access operations are initiated when the acceleration bit (A) of the command message is set to a logic ‘0’. The operation to be performed is indicated by the Access Selection bit (AX) of the command message. Access Selection Bit (AX) Operation 0 Register Read 1 Register Write Register Access operations include a parity bit (P). Odd parity is employed. The number of logic ‘1’ bits in the Register Access operation must be an odd number. 4.4.1 Register Write Request During a register write request, bits 12 through 8 contain a five-bit address, and bits 7 through 0 contain the data value to be written. Writable registers are defined in Table 3. The response to a register write operation is shown in Table 30. The response is transmitted on the next SPI message if and only if all of the following conditions are met: • No SPI Error is detected (Reference Section 4.5.1) • No MISO Error is detected (Reference Section 4.5.2) • The ENDINIT bit is cleared (Reference Section 3.1.6.3) – This applies to all registers with the exception of the DEVCTL register (Only Bits 6 and 7 can be modified) • No Invalid Register Request is detected (Reference Section 4.5.3.2) If the above conditions are met, the device responds to the register write request as shown in Table 30. Otherwise, the device Responds as specified in Section 4.5. Register write operations do not occur internally until the transfer during which they are requested has been completed. In the event that a SPI Error is detected during a register write transfer, the write operation is not completed. 4.4.2 Register Read Request During a register read request, bits 12 through 8 contain the five-bit address for the register to be read. Bits 7 through 0 must be logic ‘0’. Readable registers are defined in Table 3. The response to a register read operation is shown in Table 30. The response is transmitted on the next SPI message if and only if all of the following conditions are met: • No SPI Error is detected (Reference Section 4.5.1) • No MISO Error is detected (Reference Section 4.5.2) • No Invalid Register Request is detected (Reference Section 4.5.3.2) If the above conditions are met, the device responds to the register read request as shown in Table 30. Otherwise, the device responds as specified in Section 4.5. MMA65xx Sensor Freescale Semiconductor, Inc. 49 4.5 Exception Handling The following sections describe the conditions and the device response for each detectable exception. In the event that multiple exceptions exist, the exception response is determined by the priority listed in Table 33. Table 33. SPI Error Response Priority Effect on Data Error Priority Exception SPI Data Arming Output PCM Output 1 SPI Error Error Response No Update No Effect 2 SPI MISO Error Error Response No Update No Effect 3 Invalid Request Error Response No Update No Effect 4 DEVINIT Bit Set Error Response No Update Disabled 5 DEVRES Error Error Response No Update Disabled 6 CRC Error Error Response No Update No Effect 7 Self Test Error Error Response No Update No Effect 8 Offset Monitor Error Error Response No Update No Effect 4.5.1 SPI Error The following SPI conditions result in a SPI error: • SCLK is high when CS is asserted • The number of SCLK rising edges detected while CS is asserted is not equal to 16 • SCLK is high when CS is negated • Command message parity error (MOSI) • Bit 15 of Acceleration Data Request is not equal to ‘0’ • Bits 4 through 11 of an Acceleration Request are not equal to ‘0’ • Bits 3 of an Acceleration Request is not equal to ‘1’ • Bits 0 through 7 of a Register Read Request are not equal to ‘0’ The device responds to a SPI error with a “SPI Error” response as shown in Table 30. This applies to both acceleration data request SPI errors, and Register Access SPI errors. The arming function will not be updated if a SPI Error is detected. The PCM output is not affected by a SPI Error. MMA65xx 50 Sensor Freescale Semiconductor, Inc. 4.5.2 SPI Data Output Verification Error The device includes a function to verify the integrity of the data output to the MISO pin. The function reads the data transmitted on the MISO pin and compares it against the data intended to be transmitted. If any one bit doesn’t match, a SPI MISO Mismatch Fault is detected and the MISOERR flag in the DEVSTAT register is set. If a valid SPI acceleration request message is received during the SPI transfer with the MISO mismatch failure, the SPI acceleration request message is ignored and the device responds with a “MISO Error” response during the subsequent SPI message (reference Table 30). The Arming function is not updated if a MISO mismatch failure occurs. The PCM function is not affected by the MISO mismatch failure. If a valid SPI register write request message is received during the SPI transfer with the MISO mismatch failure, the register write is completed as requested, but the device responds with a “MISO Error” response as shown in Table 30, during the subsequent SPI message. If a valid SPI register read request message is received during the SPI transfer with the MISO mismatch failure, the register read is ignored and the device responds with a “MISO Error” response as shown in Table 30, during the subsequent SPI message. If the register read request is for the DEVSTAT register, the DEVSTAT register will not be cleared. In all cases, the MISOERR flag in the DEVSTAT register will remain set until a successful SPI Register Read Request of the DEVSTAT register is completed. SPI DATA OUT SHIFT REGISTER D DATA OUT BUFFER Q D Q MISO R D Q MISO ERR SCLK R Figure 37. SPI Data Output Verification 4.5.3 Invalid Requests 4.5.3.1 Acceleration Data Request Mismatch Failure The device detects an “Acceleration Data Request Mismatch” error if the SPI “Acceleration Data Request” Command data listed in Table 32 does not match the internal register settings. The device responds to an “Acceleration Data Request Mismatch” error with an “Invalid Accel Request” response as specified in Table 30 on the subsequent SPI message only. No internal fault is recorded. The arming function will not be updated if an “Acceleration Data Request Mismatch” Error is detected. The PCM output is not affected by the “Acceleration Data Request Mismatch” error. Register operations will be executed as specified in Section 4.4. 4.5.3.2 Invalid Register Request The following conditions result in an “Invalid Register Request” error: • An attempt is made to write to an un-writable register (Writable registers are defined in Section 3.1, Table 3). Attempts to write to registers $09, $18, $19, $1A and $1B will result in an error. • An attempt is made to write to a register while the ENDINIT bit in the DEVCFG register is set – This applies to all registers with the exception of the DEVCTL register (Only Bits 6 and 7 can be modified) An attempt is made to read an un-readable register (Readable registers are defined in Section 3.1, Table 3). Attempts to read registers $09, $18, $19, $1A and $1B will result in an error. The device responds to an Invalid Register Request” error with an “Invalid Register Request” response as shown in Table 30. • 4.5.4 Device Reset Indications If the DEVINIT, or DEVRES bit is set in the DEVSTAT register as described in Section 3.1.11, the device will respond to acceleration data requests with an “Internal Error Present” response until the bits are cleared in the DEVSTAT register. The DEVINIT bit is cleared automatically when device initialization is complete (Reference tOP in Section 2.7). The DEVRES bit is cleared on a read of the DEVSTAT register. The arming function will not be updated on Acceleration Data Request commands if the DEVINIT or DEVRES bit is set in the DEVSTAT register. The PCM output is disabled if the DEVINIT or DEVRES bit is set. MMA65xx Sensor Freescale Semiconductor, Inc. 51 4.5.5 Internal Error The following errors will result in an internal error, and set the IDE bit in the DEVSTAT register: • OTP CRC Failure • Writable Register CRC Failure • Self Test Error • Invalid internal logic states 4.5.5.1 CRC Error If the IDE bit is set in the DEVSTAT register due to one or more of the following errors, the device will respond to acceleration data requests with an “Internal Error Present” response until the IDE bit is cleared in the DEVSTAT register. • An OTP Shadow Register CRC failure as described in Section 3.2 • A Writable Register CRC failure as described in Section 3.2 • A clock monitor CRC failure as described in Section 3.4.2 The arming function will not be updated on Acceleration Data Request commands if a CRC Error is detected. The PCM output is not affected by the CRC error. If the CRC error is in the writable register array, and the ENDINIT bit in the DEVCFG register has been set, the error can only be cleared by a device reset. The IDE bit will not be cleared on a read of the DEVSTAT register. If the CRC error is in the OTP shadow register array, the error cannot be cleared. Register operations will be executed as specified in Section 4.4. 4.5.5.2 Self Test Error If the IDE bit is set in the DEVSTAT register due to a Self Test activation failure, the device will respond to acceleration data requests with a “Self Test Error” response until the IDE bit is cleared in the DEVSTAT register. The arming function will not be updated on Acceleration Data Request commands if a Self Test Error is detected. The PCM output is not affected by the Self Test Error. The IDE bit in the DEVSTAT register will remain set until a read of the DEVSTAT register occurs, even if the internal failure is removed. If the internal error is still present when the DEVSTAT register is read, the IDE bit will remain set. Register operations will be executed as specified in Section 4.4. 4.5.6 Offset Monitor Error If an offset monitor error is present as described in Section 3.8.5, the OFFSET_X or OFFSET_Y bit in the DEVSTAT register will be set. The device will respond to an acceleration request for the corresponding axis with an “Internal Error Present” response until the OFFSET_X or OFFSET_Y bit is cleared in the DEVSTAT register. The arming function will not be updated. Once the error condition is removed, the OFFSET_X or OFFSET_Y bit in the DEVSTAT register will remain set until a read of the DEVSTAT register occurs. The PCM output is not affected by the offset monitor over range condition. Register operations will be executed as specified in Section 4.4. 4.6 Initialization SPI Response The first data transmitted by the device following reset is the SPI Error response shown in Table 30. This ensures that an unexpected reset will always be detectable. The device will respond to all acceleration data requests with the “Invalid Acceleration Data Request” response until the DEVRES bit in the DEVSTAT register is cleared via a read of the DEVSTAT register. The arming function will not be updated on Acceleration Data Request commands until the DEVRES bit in the DEVSTAT register is cleared. MMA65xx 52 Sensor Freescale Semiconductor, Inc. 4.7 Acceleration Data Representation Acceleration values are determined from the 12-bit digital output (DV) using the following equations: = Sensitivity LSB × DV Acceleration = Sensitivity LSB × ( DV – 2048 ) Acceleration For Signed Data For Unsigned Data The linear range of digital values for signed data is -1920 to +1920, and for unsigned data is 128 to 3968. Resulting ranges and some nominal acceleration values are shown in the following table. Table 34. Nominal Acceleration Data Values Nominal Acceleration Unsigned Digital Value Signed Digital Value 105g 105g 120g Unused Unused Unused 3969 - 4095 1921 - 2047 3968 1920 80.000 g 105.49 g 120.00 g 3967 1919 79.958 g 105.44 g 119.94 g • • • • • • • • • • • • • • • • • • • • • • • • 2050 2 0.083333 g 0.1099 g 0.1250 g 2049 1 0.041667 g 0.0545 g 0.0625 g 2048 0 0 g 0 g 0 g 2047 -1 -0.041667 g -0.0545 g -0.0625 g 2046 -2 -0.083333 g -0.1099 g -0.1250 g • • • • • • • • • • • • • • • • • • • • • • • • 129 -1919 -79.958 g -105.44 g -119.94 g 128 -1920 -80.000 g -105.49 g -120.00 g 1 - 127 -1921 - 2048 Unused Unused Unused 0 0 Fault Fault Fault MMA65xx Sensor Freescale Semiconductor, Inc. 53 Figure 38 shows the how the possible output data codes are determined from the input data and the error sources. The relevant parameters are specified in Section 2.4. Figure 38. Acceleration Data Output Vs. Acceleration Input MMA65xx 54 Sensor Freescale Semiconductor, Inc. 5 Package 5.1 Case Outline Drawing Reference Freescale Case Outline Drawing # 98ASA00090D http://www.freescale.com/files/shared/doc/package_info/98ASA00090D.pdf 5.2 Recommended Footprint Reference Freescale Application Note AN3111, latest revision: http://www.freescale.com/files/sensors/doc/app_note/AN3111.pdf Table 1. Revision History Revision number Revision date 3 03/2012 Description of changes • Added SafeAssure logo, changed first paragraph and disclaimer to include trademark information. • Added devices to ordering table: MMA6519KW, MMA6525KW and MMA6527KW MMA65xx Sensor Freescale Semiconductor, Inc. 55 How to Reach Us: Home Page: www.freescale.com Web Support: http://www.freescale.com/support USA/Europe or Locations Not Listed: Freescale Semiconductor, Inc. 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Freescale and the Freescale logo are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. SafeAssure and Xtrinsic are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © 2012 Freescale Semiconductor, Inc. All rights reserved. MMA65XX Rev. 3 03/2012