tpms presentation - nxp...
TRANSCRIPT
Sr.Auto FAE
Alan Yang (杨涛)
April 1 2014
TPMS Presentation
TM
F r e e s c a l e C o n f i d e n t i a l P r o p r i e t a r y
Alan Yang (杨涛)
TPMS 7*7 package Agenda
• Marketing trend
• How does TPMS module work in car
• Detailed specification of MPX87xx
• TPMS road map and comparison with the other supplier
• Our enablement resources
• Q&A
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• Q&A
TM
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, t
he Energy Efficient Solutions logo, mobileGT, PowerQUICC, QorIQ, StarCore and Symphony
are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack,
ColdFire+, CoreNet, Flexis, Kinetis, MXC, Platform in a Package, Processor Expert, QorIQ
Qonverge, Qorivva, QUICC Engine, SMARTMOS, TurboLink, VortiQa and Xtrinsic are trademarks
of Freescale Semiconductor, Inc. All other product or service names are the property
of their respective owners. © 2011 Freescale Semiconductor, Inc.
Tire Pressure motivated by Auto mega trends
Mobility for everyone• TPMS is available for all type of
vehicles including truck and busses
• Scalable solutions• Multiple pressure ranges• Multiple rotation axis• Multiple RF frequencies
Cleaner world for everyone• TPMS allows optimum tire
inflation and thus fuel consumption and CO2 emission reduction
• Maximizes tire life• European and Korean legislation
driven by CO2 reduction
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Safety for everyone• Prevent roadside breakdown and
risk of road congestion• US tread act to prevent roll over
accidents• Future possibilities to link tire
information with chassis and ADAS system
Always Connected• Provides accurate tire data to the
driver• Filling assistant app on smart
phones• Fleets & Truck: enables better tire
management
TPMS legislation around the world
Region Requirements
USA Regulation from 2005: FMVSS138 mandates TPMS for new vehicles starting from October 1st 2005
European Union Regulation from 2012: EC661-2009 mandates TPMS starting Nov 2012 for new type approved vehicles and for all new vehicles starting from Nov 2014:TPMS will be tested as part of the new EU standardized plan for vehicle periodical inspection
S. Korea / Japan Regulation from 2013: TPMS vehicles to be installed on passenger cars from
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S. Korea / Japan Regulation from 2013: TPMS vehicles to be installed on passenger cars from January 2013 for new model and January 2015 for existing model
Russia, Kazakhstan, Belarus (Eurasia)
Valid from 2015 onwards & replaces nation legislation
Indonesia, Israel, Malaysia, Philippines, Turkey
Require European whole vehicle type approval for vehicles imported from Europe. As a consequence TPMS will be required for all new vehicles in November 2014
China Recommended specificationEnforcement Standard in Preparation
TPMS potential market size
• 100 Million new cars sold per year by the end of the decade
− 4 wheel per car + spare tires + winter tires
− Module Replacement market
• 1 billion cars on the road worldwide
− Great aftermarket opportunity
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Great aftermarket opportunity
− Great potential for tire mounted solutions
• Heavy trucks, busses, motorcycles
• Market outside of transportation requiring battery operated wireless pressure sensing
MPXY8700 Packaging
PcellGcell
MCU + RF
QFN 9 x 9 mmCavity Package(Cross Section)
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PcellGcell
Gel
Gel
Plastic flagLeadframe
Metal cap
Plastic housing
Plastic housing
Not to scale. For illustration purposes only.
Selective encapsualtion
(Cross Section)
TM
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, t
he Energy Efficient Solutions logo, mobileGT, PowerQUICC, QorIQ, StarCore and Symphony
are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack,
ColdFire+, CoreNet, Flexis, Kinetis, MXC, Platform in a Package, Processor Expert, QorIQ
Qonverge, Qorivva, QUICC Engine, SMARTMOS, TurboLink, VortiQa and Xtrinsic are trademarks
of Freescale Semiconductor, Inc. All other product or service names are the property
of their respective owners. © 2011 Freescale Semiconductor, Inc.
Tire Performance Issues
Aquaplaning (water depth >2 mm)Worsening until around 1.5 ba, then improvement due to bell formation of tread
centre inwards (at rated load)
General durability Reduced with lower pressures
Test Stand durabilityA reduction by 0.5 bar results in a worsening of 15 km/h in endurance (e.g.
Failure at 185 km/h instead of 200 km/h)
Resistance to curb impactA reduction by 0.5 bar results in damage sustained at 20% lower speed (e.g. at
40 km/h instead of 50 km/h)
Bead unseating from rimThe limit value for unseating of bead from rim lies between the operating
pressure and 1 to 1.2 bar. For safety reasons, this should never be lower
Wear A tire with 20% lower pressure has a running life around 30% less
Rolling Resistance A reduction by 0.5 bar results in an increase in rolling resistance of around 15%
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Rolling Resistance A reduction by 0.5 bar results in an increase in rolling resistance of around 15%
Tread NoiseA deviation of 1 bar from normal pressure (2 to 2.5 bar) worsens the noise level
by 2 dbA (66%).
Handling on dry and wet surfacesOn a mid-class car, an air pressure deviation of 0.2 bar from one axle is
noticeable.
(Source: Michelin Tires)
Tire Performance Issues
140
130
120
110
108
106
104
102
100
80
60
40
20
Serv
ice L
ife (
%)
Fuel U
se (
%)
Rolli
ng R
esis
tance (
%)
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1001012.0 1.7 1.4 1.1
0120 110 100 90 80 70 60 50 40 30
Tire Pressure (% of Specified) Tire Pressure (bars)
Decreased Tire Life withLower Pressure
Increased Fuel Use andRolling Resistance with
Lower Pressure
(Source: Continental Tires)
Pressure Accuracy
• Measurement accuracy target varies with OEM− Typical accuracies better than 8-10 kPa (1.2 – 1.4 psi)
− Typical resolutions of 1 to 2 kPa (0.15 – 0.30 psi)
• Accuracy over temperature, supply voltage and life of the tire/system
• Must warn based on the correct Cold Inflation Pressure (CIP)
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• Must warn based on the correct Cold Inflation Pressure (CIP) specified for the vehicle
• CIP limits usually set in the chassis receiver for a specific vehicle
Pressure Accuracy
• Effects of absolute vs. gauge pressure at altitude− In tire sensors measure absolute pressure
− Typical tire gages measure differential (gauge) pressurerelative to the atmosphere
• CIP is defined as the pressure of the tires afterthe has been stopped for at least 1 hour
• The “corrected” pressure using the Ideal Gas Lawis not used
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is not used− It is not the mass of air present setting tire performance
− It is pressure of the air that defines the load carrying capability and performance of the tire
• Generally accepted to use absolute pressure with a fixed atmospheric offset (approx 100 kPa = 14.5 psi)
TPMS System Solutions
• Direct (Measure Pressure in the Tire)− Use absolute pressure sensor inside the tire volume
− Communication via LF and/or RF links
− Mounted inside the tire/wheel
� On the wheel (valve stem or drop center)
� On the tire (side wall, bead area or tread belt)
− Powered by energy source
� Internal battery
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� Internal battery
� Source other than battery (battery-less)
• Indirect (Measuring Some Other Parameter)− Infer under-inflation by using parameter other than pressure sensing
� Wheel speed variations
� Ride height variations
� Tire vibration variations
− No power source required on the wheel/tire
Tire Pressure Monitor Systems: Indirect Measuring
• Implemented through ABS wheel speed sensors
• ABS system is able to measure individual wheel speed and compare it against other wheels
• If a wheel is moving faster, it is very likely it is under-inflated
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very likely it is under-inflated
http://www.aa1car.com/library/diagnosing_abs_wheels_speed_sensors.htm
≠
Tire Pressure Monitor Systems: Direct vs. Indirect
Direct Indirect
Precision ☺ �
Reaction time ☺ �
Detection of multiplefaults
☺ �
Position-dependantpressure warning
☺ �
Robustness under ☺ �
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Robustness under different driving conditions
☺ �
Number of additional components
� ☺
System cost � ☺
Required driver interaction
☺ �
Additional comfort features
☺ �
Tire Pressure Monitor Systems: Indirect Measuring
LikeLike
• Hardware reuse (ABS system)
• Cheap
Don’t likeDon’t like
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• Measurement relative to other tires
• Can only sense
• One under-inflated tire
• Three tires are under-inflated
• Two diagonally-positioned tires are under-inflated
• Will not work with under-inflated tires
• 2 on the same axle
• 2 on the same car side
• All 4
Direct TPMS Mounting Methods
Tire Wall Tire Tread Mount
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Drop Well MountValve Stem Mount
• Other Direct TPMS system features in the marketplace
−Display actual individual tire pressures
− “Tire Localization”determine location of tire on car
− “Auto-Learn”determine tire IDs on the car
TPMS Architectures
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determine tire IDs on the car
− “Initiation” triggering a pressure reading on demand
−Motion detection to change monitoring rates
−Motion detection to save battery power when parked
−Diagnostics for manufacturing and field service
Sensor Package Comparison
Freescale
MPXY87XX Competitor Freescale
MPXY85XX
/MPXY86XX
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• QFN 9x9x2.3mm
• PG-DSOSP-14-6• 9.24 X 11.09 X 3.9 mm
�MPXY85xx/86xx smaller in size will help on module’s size, weight and cost.
Top Level TPMS Model
Pressure
MotionSensor
3VBatt
LFReceiver
RFEnergy
Coil
LFSignal
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PressureSensor
TempSensor
Controller RFTransmitter
Ant Energy
Tire Pressure Monitoring Body Receiver
Antenna
RF
Stand along TPMS displayClusterInfotainment
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Stand along TPMS receiverOr RKE SystemOr PKE System
MCU &Control
RFReceiver LF
24 psi
MILBasicSystems
GeneralSystems
TM
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, t
he Energy Efficient Solutions logo, mobileGT, PowerQUICC, QorIQ, StarCore and Symphony
are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack,
ColdFire+, CoreNet, Flexis, Kinetis, MXC, Platform in a Package, Processor Expert, QorIQ
Qonverge, Qorivva, QUICC Engine, SMARTMOS, TurboLink, VortiQa and Xtrinsic are trademarks
of Freescale Semiconductor, Inc. All other product or service names are the property
of their respective owners. © 2011 Freescale Semiconductor, Inc.
• Microcontroller• S08 core, 0.25um SGF technology
• 16 kB SGF flash (8kB firmware, 8kB customer), 512B RAM, 64 parameter registers
• 10 bit ADC, temperature sensor and thermal restart
• 1-channel LF detector and decoder
• 8 MHz clock, 2-ch timer, 1 kHz LFO
• Integrated RF transmitter
• Frac-N PLL based transmitter, 315/434 MHz
• FSK/ASK modulation
• Manchester or bi-phase encoding
-1dBm to +8 dBm output power
512b
RAMRAM
LFRDetect and Decode16K FlashFlash
TPM2-ch
Register64 Bytes
10-bit ADCADC
BDM
LVD BG
Wakeup Timer
OSC 8 MHz
LFO 1 kHz
Temp Sensor
Temp Restart
UHF TX315 / 434 MHz C to V
Pressure Cell XZ-axis Accel
S08 Core
FXTH87xxxx6T1 Tire Pressure Monitoring System
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• -1dBm to +8 dBm output power
• Pressure Sensor• CMOS capacitive p-cell w/o signal conditioning
• Acceleration Sensor• Single XZ die
• Package• FAM 7x7mm QFN w/ gel fill
• Design Considerations:• RF Tx (7mA @ 5 dBm)
• LF Rx (4uA, snif)
• Process Technology – 0.25um
• Core Type – S08
• Voltage Supplies – 1.8V to 3.6V (transmit)
• Voltage Supplies – 2.3V to 3.6V (measure)
• Packaging Requirements – Media protection
Pressure Cell XZ-axis Accel
FXTH87xxxx6T1 Tire Pressure Monitoring System
Integrated Tire Pressure Monitoring System (TPMS) with smallest footprint (7mmx7mm) Integrated Tire Pressure Monitoring System (TPMS) with smallest footprint (7mmx7mm) lowest power consumption, largest customer memory size (8kB flash, 512byte RAM) lowest power consumption, largest customer memory size (8kB flash, 512byte RAM)
and unique dualand unique dual--axis accelerometer architectureaxis accelerometer architecture
• The compact 7 x 7 mm industry-leading package enables smallest module design for lighter weight
• Including an XZ-axis accelerometer offers customers motion detection and tire
• Robust package design with encapsulated inter-chip bond wires
Smallest Package Size Integrated XZ-Accelerometer Robustness / Power
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module design for lighter weight applications
• Same height as QFN 9x9 for smooth transition to QFN 7x7 solutions
• Highest degree of functional integration:
• Dual-axis accel, LF, RF, Pressure, MCU in one package
motion detection and tire localization capabilities
encapsulated inter-chip bond wires
• Storage temp: -50C / +150C
• Smallest RF transmit battery consumption
• 8kB of customer flash memory gives more application flexibility. Possible interface with external memory if required
• 512byte RAM
Troubleshooting: Typical Currents at ambient temperature
Normal OperationNormal OperationRF Behavior (To be
added to normal operation)
RF Behavior (To be added to normal
operation)RESETRESET BKGDBKGD
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RUN Mode2 mA
RUN Mode2 mA
STOP473 uA
STOP473 uA
STOP10.5uA
STOP10.5uA
RF ON Adder 77 uA
RF ON Adder 77 uA
RF Transmission
6mA
RF Transmission
6mA 1.2 mA1.2 mA 1.2 – 1.5 mA1.2 – 1.5 mA
Competitive Positioning & Value Proposition
• Customers cost benefit
− Smaller in size: 7mmx7mmx2.2mm
− Saving on board size , potting and housing materials.
− Saving on module weight (car OEM requirement)
− Boot Loader design allow uploading SW through LF – reduce cost of car OEMs call back cost by uploading SW at site.
− Auto-localization by using dual axis accelerometers.
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• Longer battery life
− 35% RF transmitting power consumption. <7mA at 5dBm
• Lower business risk
− Flash 8k space, 512 bytes RAM for customers
− 33% more space enabling a module suitable for more car models. (inventory/operation/ production management benefit).
− Improve cash flow for aftermarket tire shop by dual axis universal module and bigger memory size.
Lausitz: Significant Requirements - General
Characteristic Description
Data InterfacesLow Frequency Receiver
FrequencyModulationCarrier Sensitivity RangesData Sensitivity Ranges
RF TransmitterFrequencyModulationTransmit Power
125 kHzASK70 / 10, 14 / 2, & 3 / 0.5 mV ( Det / No Det
14 / 2 & 2.5 / 0.25 mV ( Det / No Det )
315 , 434 MHzASK, FSK5 dBm, 8dBm
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Package 7 x 7 mm 24 –Pin QFN
Physical Architecture – MCU HSC08 - SZK16 dedicated MCU
Physical Architecture – Pressure Transducer Capacitive cell with 100 up to 900 kPa range
Temperature sensor ∆VB sensor with -40 to +125°C range
Voltage Sensor Internal bandgap voltage reference
Physical Architecture – Z-Axis TransducerX-Axis Transducer
Teeter Totter ElementX-lateral Element
Lausitz and Nogaro Portfolio Under Development
Logical part number Device name (QFN 7x7)Operating Temp
range
P-cell range
(kPa)
Axis of
accelX-range Z-range
Nogaro FXTH8705026T1 -40C / + 125 C 100-450 Z NA -270g /+ 350g range with 40g sens
Nogaro FXTH870502DT1 -40C / + 125 C 100-450 Z NA -270g /+ 350g range with 40g sens
Lausitz FXTH8705116T1 -40C / + 125 C 100-450 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens
Lausitz FXTH870511DT1 -40C / + 125 C 100-450 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens
Nogaro FXTH8709026T1 -40C / + 125 C 100-900 Z NA -270g /+ 350g range with 40g sens
Nogaro FXTH870902DT1 -40C / + 125 C 100-900 Z NA -270g /+ 350g range with 40g sens
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Lausitz FXTH8709116T1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens
Lausitz FXTH870911DT1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -210g/+240g range with 60g sens
Lausitz FXTH8709126T1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -270g /+ 350g range with 40g sens
Lausitz FXTH870912DT1 -40C / + 125 C 100-900 XZ -70g/+80g range with 10g sens -270g /+ 350g range with 40g sens
TM
Freescale, the Freescale logo, AltiVec, C-5, CodeTEST, CodeWarrior, ColdFire, C-Ware, t
he Energy Efficient Solutions logo, mobileGT, PowerQUICC, QorIQ, StarCore and Symphony
are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. BeeKit, BeeStack,
ColdFire+, CoreNet, Flexis, Kinetis, MXC, Platform in a Package, Processor Expert, QorIQ
Qonverge, Qorivva, QUICC Engine, SMARTMOS, TurboLink, VortiQa and Xtrinsic are trademarks
of Freescale Semiconductor, Inc. All other product or service names are the property
of their respective owners. © 2011 Freescale Semiconductor, Inc.
TPMS Roadmap
Tire Pressure Monitoring
MPXY85xx - Z-axis450/900 kPa
0.25uSGF, 2-Poly, 9x9 Cav QFN C90FGUHV IP Blocks
UMEMS Phs 4P C90FGUHV, UMEMS 4P, 5x5 FAM or CSP
U-TPMS XZ-axis450/900/1500 kPa
C90FGUHV, UMEMS-4P, 5x5 FAM or CSP
Nogaro Z axis450/900 kPa
0.25uSGF, 2 Poly, 7x7 FAM
Nogaro Z-axis450/900 kPa
0.25uSGF, 2-Poly, 7x7 FAM
Lausitz axis450/900 kPa
Lausitz XZ-axis450/900 kPa
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Lausitz axisUp kPa
0.25uSGF, 2 Poly, 7x7 FAM
Lausitz XZ-axisUp tp 1500 kPa
0.25uSGF, 2-Poly, 7x7 FAM
MPXY86xx - XZ-axis450/900 kPa
0.25uSGF, 2-Poly, 9x9 Cav QFN
Left Edge :
First Sample Date
Execution
Proposal
Planning
Production
Right Edge :
Product Qualification
Not resourced
2013 2014 20152Q 3Q 4Q1Q 2Q 3Q 4Q1Q 2Q 3Q 4Q1Q 2Q 3Q 4Q1Q
2016
450/900 kPa0.25uSGF, 2 Poly, 7x7 FAM
450/900 kPa0.25uSGF, 2-Poly, 7x7 FAM
Preliminary schedule. To be updated by August 31, 2013
Tire Pressure Monitor Sensor Roadmap Change-points
Gen2 Gen3 Gen4 Gen5
Package SOIC-20Bottom-side cavity;4-die
IntroduceQFN 9x9, Open top-side cavity;3-die
Introduce Film-Assist Mold QFN 7x73-die
Eliminate Die-to-Die Bond wires;2-die
ASIC Node
ASIC Design
TSMC 250nm SGF
Dedicated pressure & inertia interfaces( A/D & C/V )
TSMC 250nm SGF
Muxed C-V signal chains w/ Σ∆ ADC, digital filters;Up-integrate RF Tx
TSMC 250nm SGF
Muxed C-V signal chains w/ Σ∆ ADC, digital filters;Optimized LF/RF
Introduce 90nm TFS
Battery-less powerSystem ID, extended BIST, & selectable sensitivities
MEMS Nodes 2-poly inertia, 2-poly inertia & p-cell 2-poly inertia & p-cell Introduce eHARMEMS
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MEMS Nodes
MEMS Design
2-poly inertia,PIDR73 pressure
X-lat & teeter-totter;Redundant p-chip w/Integrated C-V
2-poly inertia & p-cell
X-lat & teeter-totter;Redundant p-cell
2-poly inertia & p-cell
X-lat & teeter-totter;Redundant p-cell
Introduce eHARMEMSfor pressure,eHARMEMS inertia
Combined Self Test + Sense
Test Physical @ probe & final
Physical @ probe & final
Physical / Electrostatic @ probe & final
Electrostatic @ probe & final
Certification &/orAssessment
AEC-Q100 AEC-Q100 AEC-Q100 AEC-Q100ASIL-QM, B target
Competitive Positioning & Value Proposition
• Smaller in size:
− Saving on board size (customer cost benefit)
− Saving on potting material (customer cost benefit)
− Saving on module weight (car OEM requirement)
• Flash 8k space for customers
− 33% more space enabling a module suitable for more car models. (inventory/operation/ production management benefit).
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production management benefit).
• Unique with dual-axis accelerometer
− enabling tire location determination without the need for user intervention and/or the use of LF initiator(s).
• Lower RF transmitting power consumption
− <7mA at 5dBm
• g-cells based on technology used in airbags we shipped close to1 billion unit level.
Power Consumption Comparison
CompetitorFreescale
MPXY8XXX
Operating Voltage
MCU, RF Transmitter1.9V to 3.6V 1.8V to 3.6V
Operating Voltage
Measurement 2.1V to 3.6V 2.3V to 3.6V
Stop Idd@ 25 °°°°C 0.7 uA 0.7 uA
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RF Output 5dBm @315MHz 3V 10 mA <7 mA
RF Output 5dBm @434MHz 3V 10 mA <7.6 mA
�MPXY85xx/86xx have lower RF transmitting power consumption will help on battery life and cost.
MCU Core Comparison
CompetitorFreescale
MPXY8XXX
MCU Core 8051 9S08
Flash for Customer 6K 8K
RAM 256 Byte 512 Byte
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�MPXY85xx/86xx with 8k flash for customers will allow one module for more car models by offering 33% more space for customers’ software.
�Benefit for customers’ inventory/production/operation management.
Sensor Performance Comparison
CompetitorFreescale
MPXY8XXX
Low Pressure Range
100-450 kPa
Maximum error
± 7 kPa0 ℃ to 50 ℃
± 7 kPa0 ℃ to 70 ℃
± 9 kPa0℃ to 70 ℃
± 10.5 kPa-20 ℃ to 85 ℃
± 17.5 kPa-40 ℃ to 125 ℃
± 16.8 kPa-40 ℃ to125 ℃
Medium Pressure Range
±10 kPa0 ℃ to 70 ℃
℃ ℃
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Medium Pressure Range
100-900 kPa
Maximum error
± 15 kPa-20 ℃ to 85 ℃
±24 kPa-40 ℃ to 125 ℃
Accelerometer Only Z-axis
Z-axisXZ-axis
No Accel
�MPXY85xx/MPXY86xx offer better temp performance enable better system accuracy.
Sensor Performance Comparison (continued)
CompetitorFreescale
MPXY8XXX
Max Operating Temperature -40 ℃ to 125 ℃ -40 ℃ to 125 ℃
Temperature Error
±3 ℃(-20 ℃ to 70 ℃)
±3 ℃(-35 ℃ to 70 ℃)
±5 ℃℃ ℃
±5 ℃℃ ℃
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±5 ℃(-40 ℃ to 125 ℃)
±5 ℃( -40 ℃ to 125 ℃)
Voltage Range 1.9V to 3.6V 1.8V to 3.6V
Voltage Error±100 mV
(-40 ℃ to 125 ℃)±75 mV
(-40 ℃ to 125 ℃)
Sensor Package Comparison
Freescale
MPXY87XX Competitor Freescale
MPXY85XX
/MPXY86XX
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3636
• QFN 9x9x2.3mm
• PG-DSOSP-14-6• 9.24 X 11.09 X 3.9 mm
�MPXY85xx/86xx smaller in size will help on module’s size, weight and cost.
RF Basics�The transmitter generates a radio frequency (RF) signal
− OOK : The signal is canceled during low level
− FSK : The frequency of the wave varies with the value of the modulating signal
�The transmitter matching network optimize the transfer of power until the antenna
�The transmitter antenna transforms this RF signal to an electromagnetic wave
�The wave propagates to the receiver’s antenna
�The receiver antenna collects the wave at RF frequency
�The receiver matching network optimizes the transfer of power until the receiver input
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input
�The receiver processes the signal
TransmitterTransmitter ReceiverReceiver
Or FSKmodulation
Either OOKmodulation
TransmitMatchingNetwork
ReceiveMatchingNetwork
RF of TPMSWhat is impact RF receiving rate?
� RF Receiver design (RF antenna gain, device sensitivity, RF antenna matching, position & direction on car )
� RF emitter design (RF antenna gain, RF power, RF antenna matching, direction)
� RF protocol (FSK or ASK? Repeat times?)
RF Receiving Rate Power consumption Comment
FSK ☺ � FSK is less susceptible to interference
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interference
OOK � ☺ Lower cost for RF Receiver side and emitter side(Shrader)
Lower Baud Rate ☺ � It need to repeat the RF frame when the receiving rate can’t meet the target.Higher Baud Rate � ☺
Shorter Length of Protocol
☺ ☺
Higher RF power ☺ � It need to repeat the RF frame when the receiving rate can’t meet the target.
RF of TPMS
RF Frame Format
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RF Data Encoding�Manchester encoding (most customer)
� Customize encoding (S&T, TTE and etc.) NRZ encoding to resolve it!
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�Bi-phase encoding
Inter-Frame Spacing of RF
To avoid frame collisions between data from multiple sensors
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TPMS MCU power modes
Variable RUN STOP4 STOP1
Active clocks HFO,MFO,LFO
MFO,LFO
LFO
RAM (512 bytes) Active Stand-by Off
PARAM (64 bytes)
Active Active Active
RF Transmitter Optionally On Optionally On Optionally On
LF Receiver Optionally On Optionally On Optionally On
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LF Receiver Optionally On Optionally On Optionally On
Sensors Optionally On Optionally On Off
MCU On and clocking Stand-by, not clocking
Off
PWU ON ON ON
GPIOs ON Levels maintained
Hi-Z
Interrupts Optionally ON Optionally ON Some On, Someoff, will start code from main()
RSM RSM
TPMS RF Receiver
Direct TPMS Architecture (单向单向单向单向)
RSM
SPARE
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RSM: Remote Sensing Module
RSM RSM
Direct TPMS Architecture (双向双向双向双向)
RSM RSM
CA
N
TPMS RF Receiver
LFLF
LF LF
RSM
SPARE
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RSM: Remote Sensing ModuleLF: LF Initiator
RSM RSMC
AN LFLF
LF in TPMS SystemLF emitter in car OEM production line LF emitter in aftermarket
Automatic
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Automatic product line
Handheld tool
Handheld tool
Difference of LF Tool
LF on car (Dual way) Automatic product Line
Handheld LF emitter LF in bootloader
Trigger TPMS moduleSwitch the state (stationary, rolling, localization)
•Diagnostic (pressure, accel, battery, state) and record (ID, car module, date)
•Car model matching, tire position•Diagnostic (pressure, accel,
• Programming for different car model•Upgrade code
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localization) module, date) (pressure, accel, battery, state) and record (ID, car module, date)
•Upgrade code
40 – 90 cm ? 10 - 50 cm About 10 cm
Above 150 cm is not allowed
Above 150 cm is not allowed
Above 100 cm is not allowed
Above 30 cm is not allowed
LF Receiver
• Amplitude• frequency• duration
Carrier Mode
Data Mode
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• Carrier Mode + Datagram in Manchester format
• Data Mode with no Manchester decoding• Used in rare cases
Direct Mode
LF Protocol�Standard LF telegram Manchester code (New TPMS system)
SYNC patterns
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� Special LF telegram (TPMS for replacement)
200 +/- 20 ms
20 +/- 2 ms 10 +/- 1 ms
Typical TPM Operational Parameters
Parameter Value Units
Data Measurement Interval
Motion
Parked
3
15
sec
minute
Data Transmission Interval
Motion
Parked
60
60
sec
minute
RF Transmission Protocol
Bit Rate 9600 bits/sec
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Bit Rate
Bits/Frame
Frames/Datagram
Pressure Change Alert
9600
90
4
256
bits/sec
bits
frames
frames
Diagnostic Modes 6 modes
Pressure Change Alert 15 kPa
Pressure Measure Range 100 to 900 kPa
Temperature Measure Range -40 to +125 °C
Example TPM Operational Profile
Moving (3650 hrs)
10 Years (87600 hrs)
25000 km/yrdecaying 1500 km/yr
Total Distance182500 km
4%
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Assume ConstantTemperature and Voltage
Parked (83950 hrs)
Average Speed of50 km/hr
Total Time Moving3650 hrs
96%
35%
10%
18%
Battery life and Power Consumption
Standby
Self Discharge
Reserve
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21%16%
ProcessingTransmit
Assume 250 mA-hr Battery205 mA-hr used (including self-discharge)
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Element Used for… Provided by MPXY8XXX
Absolute Pressure Sensor Acquiring tire pressure
Acceleration Sensor(s) Determining if the vehicle is moving deciding which wheel it is (MPXY86XX)
Battery Providing power to thesystem
Timer Deciding when to transmit
MPXY87XX/86XX/85XX
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Timer Deciding when to transmit
Control Unit (MCU) Gluing all actions together
RF Transmitter Sending data to the vehicle
LF Receiver Getting instructions from the outside world
Plastic/Metal housing Holding everything together
“Putting” Isolating electronic components from tire “goo”
Algorithm Perform actions systematically
Literature
• Data Sheet
− Describes Silicon
− FXTH87xxxx_rev0 3.pdf
• User Guide
− Describes Firmware
− FXTH87xx11_ug_213.pdf (2-axes
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− FXTH87xx11_ug_213.pdf (2-axes products)
− ngo_ug_294.pdf (1-axis products)
• Reference Manual/Application notes
− AN4277: Interfacing to firmware
− AN4391: LF design considerations
MPXY87XX/86XX/85XX : Freescale Firmware
• Physically, one 16Kbyte Flash block
• First half is empty
− 8kbyte for user
• Second half contains Freescale firmware
− Low-level drivers
− Math functions
Individual Trim/compensation
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− Individual Trim/compensation
− UniqueID
− CRC
− Interrupt vectors
MPXY87XX/86XX/85XX : Calling Freescale Firmware (1)
• MPXY87XX/86XX/85XX User Guide contains documentation for all in-flash firmware routines
• All routines can be called through an absolute-address pointer
Absolute Address Return Type Function
$E000 Void TPMS_RESET
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$E000 Void TPMS_RESET
$E003 UINT8 TPMS_READ_VOLTAGE
$E006 UINT8 TPMS_COMP_VOLTAGE
$E009 UINT8 TPMS_READ_TEMP
$E00C UINT8 TPMS_COMP_TEMP
… … Refer to User Guide for complete list
MPXY87XX/86XX/85XX : Calling Freescale Firmware (2)
• The User Guide also contains a function definition
− For example, � UINT8 TPMS_READ_VOLTAGE(UINT16 *u16UUMA)
• Pointers to absolute addresses casted as pointers to functions can be declared for each firmware function
− For example,− #define TPMS_READ_VOLTAGE ((uint8_t(*)(uint16_t*))((uint16_t)0xE003))
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• Each pointer can then be treated as a regular C function
− For example,� u8Status = TPMS_READ_VOLTAGE(gau16UUMA);
MPXY87XX/86XX/85XX : Calling Freescale Firmware (3)
• Interrupts are passed to the user directly unless owned by Freescale− ISRs owned by Freescale:� ADC
− ISRs flagged by Freescale before being passed to the user:� RFM
� KBI
� RTI
� PWU
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� PWU
� LVD
• User must declare pseudo-vectors and handle each interrupt as if it were its own
MPXY87XX/86XX/85XX : Other firmware functions
• Math− Checksum, CRC8, CRC16, 16-bit multiply,
− Square Root, Weighted average
• Measurements− Read analog voltage on PTA0, Read analog voltage on PTA1, Read
acceleration with dynamic offset loading
• RF− Calculate power dynamically, Read RF buffer, Reset RF configuration,
• Timing compensation
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• Timing compensation− Low-frequency clock compensation, Medium frequency clock compensation,
• Simulated SPI− Read, write
• LF Reception− Enable LF, decode data
• Flash− Write to flash, Erase flash page, Read UniqueID
Hardware: Schematic Example
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LF Receiver125 kHz
XTAL26 MHz
Matching (RF Emitter)315/434MHz
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Power-saving strategies
• Periodically call TPMS_READ_* routines, but only call TPMS_COMP_* routines if raw values have shifted significantly or if a long period of time has elapsed.
• When calling TPMS_COMP_PRESSURE or TPMS_COMP_ACCELERATION, reutilize existing voltage and temperature data instead of requesting new data
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temperature data instead of requesting new data
Measurement Uses
• Battery Voltage:
− Transmitted to car
− Helps unit determine EOL
• Temperature:
− Used to determine if device is Out Of Operation Range
• Pressure:
Transmitted to car
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− Transmitted to car
− Main function of the device – determine if tires are correctly inflated
• Accelerometer(s):
− Customer IP goes into different functionalities
Uses for acceleration
• Determine operation mode (parking/running)
• Determine wheel location
• Determine wheel position
• Determine thread’s wear
• ??
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TPMS_READ_ACCEL functionality
Zra
w (
counts
)
Threshold
Park Mode
Moving
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• TPMS_READ_ACCEL and TPMS_COMP_ACCEL are useful when trying to determine whether a vehicle is moving or is stopped
• i.e. Set a threshold, determine if the threshold has been passed – Car is moving
Time (s)
TPMS_READ_ACCEL functionality
Zra
w (
counts
)
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• TPMS_READ_ACCEL can also be used to determine position in the tire
• i.e. Each local maximum indicates top-most position in the tire, each local minimum indicates bottom-most position in the tire
Time (s)
TPMS_READ_ACCEL limitations
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• Assume 17-inch rim (diameter = 43.18 cm; radius = 21.59 cm)• Using centrifugal force formula
• Range, is +/- 33.9 km/h
Hardware: Layout (Silk Top)
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Hardware: Layout (Top Layer)
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Hardware: Layout (L2 GND)
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Hardware: Layout (L3 Power)
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Hardware: Layout (Bottom Layer)
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Hardware: Layout (Silk bottom)
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