sx8646 Semtech Corporation, sx8646 Datasheet
sx8646
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sx8646 Summary of contents
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... ADVANCED COMMUNICATIONS & SENSING G D ENERAL ESCRIPTION The SX8646 is an ultra low power, fully integrated 8- channel solution for capacitive touch-buttons and applications. Unlike many capacitive touch solutions, the SX8646 features dedicated capacitive sense inputs (that requires no external components) in addition to 8 general purpose I/O ports (GPIO). Each ...
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... Software Reset 3.15 Interrupt 3.15.1 Power up 3.15.2 Assertion 3.15.3 Clearing 3.15.4 Example Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Table of Contents ............................................................................................................ 1 ............................................................................................................... 4 ................................................................................................. 7 ........................................................................................................ 10 © 2010 Semtech Corp. 2 SX8646 DATASHEET ...
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... PPLICATION NFORMATION ACKAGING NFORMATION 8.1 Package Outline Drawing 8.2 Land Pattern Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers .............................................................................. 36 ...................................................................................................... 65 ........................................................................................................ 66 © 2010 Semtech Corp. 3 SX8646 DATASHEET ...
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... Pinout Diagram Figure 1 8646 yyww xxxxx R05 yyww = Date Code xxxxx = Semtech lot number R05 = Semtech Code Marking Information Figure 2 © 2010 Semtech Corp. 4 DATASHEET 22 21 gnd 20 gpio5 19 gpio4 18 gpio3 17 gpio2 16 gnd 15 gpio1 14 www.semtech.com SX8646 ...
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... General Purpose Input/Output 7 Digital Core Decoupling, connect to a 100nF decoupling capacitor Ground Active Low Reset. Connect to VDD if not used. Analog Core Decoupling, connect to a 100nF decoupling capacitor Capacitive Sensor 0 Exposed pad connect to ground Pin description Table 1 © 2010 Semtech Corp. 5 SX8646 DATASHEET www.semtech.com ...
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... ADVANCED COMMUNICATIONS & SENSING 1.4 Simplified Block Diagram The simplified block diagram of the SX8646 is illustrated in Figure 3. Figure 3 1.5 Acronyms ASI Analog Sensor Interface DCV Digital Compensation Value GPI General Purpose Input GPO General Purpose Output GPP General Purpose PWM MTP Multiple Time Programmable ...
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... I2C interface (v) In the event the host processor is reset or undergoes a power OFF/ON cycle recommended that the host also resets the SX8646 and assures that parameters are re-written into the SPM (should these differ to the parameters held in NVM). 2.3 Thermal Characteristics ...
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... VDD and rising INTB type 0402, tolerance +/-50% vdig type 0402, tolerance +/-50% vana type 0402, tolerance +/-10% int type 0402, tolerance +/-50% vdd Electrical Specifications Table 5 © 2010 Semtech Corp. 8 SX8646 DATASHEET Min. Typ. Max. 175 225 80 110 8 17 0.7*VDD VDD + 0.3V V VSS - 0.3V 0.8 ± ...
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... HIGH t SU;DAT t HD;DAT t SU;STA t HD;STA t SU;STO t BUF t SP I2C Timing Specification Table 6 I2C Start and Stop timing Figure 4 I2C Data timing Figure 5 © 2010 Semtech Corp. 9 SX8646 DATASHEET Min. Typ. Max. Unit 400 KHz 1.3 us 0.6 us 100 0.6 us 0.6 us 0.6 us 500 us 50 ...
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... A finger approaching the capacitive sensors will change the charge that can be loaded on the sensors. The SX8646 measures the change of charge and converts that into digital values (ticks). The larger the charge on the sensors, the larger the number of ticks will be. The charge to ticks conversion is done by the SX8646 Analog Sensor Interface (ASI). ...
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... LED will fade-in without any host interaction over the I2C. In case the Autolight feature is disabled then the host will decide to start a LED fading-in period, simply by setting the GP0 pin to ‘high’ using one I2C command. The SX8646 will then slowly fade-in the LED using the PWM autonomously. ...
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... In most applications the reaction time needs to be fast when fingers are present, but can be slow when no person uses the application. In case the SX8646 is not used for a specific time it can go from Active mode into Doze mode and power will be saved. This time-out is determined by the Passive Timer which can be configured by the user or turned OFF if not required ...
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... For some applications a single button touch might cause undesired wakening up and Active mode would be entered too often. The SX8646 offers therefore a smart wake-up sequence feature in which the user needs to touch and release a correct sequence of buttons before Active mode will be entered. This is explained in more detail in the Wake-Up Sequence section ...
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... ADVANCED COMMUNICATIONS & SENSING 3.5 Sensors on the PCB The capacitive sensors are relatively simple copper areas on the PCB connected to the eight SX8646 capacitive sensor input pins (CAP0…CAP7).The sensors are covered by isolating overlay material (typically 1mm...3mm). The area of a sensor is typically one square centimeter which corresponds about to the area of a finger touching the overlay material ...
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... The larger the number the cycles are repeated the larger the signal out of the ADC with improved SNR. The sensitivity is therefore directly related to the number of cycles. The SX8646 allows setting the sensitivity for each sensor individually in applications which have a variety of sensors sizes or different overlays or for fine-tuning performances. The optimal sensitivity is depending heavily on the final application ...
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... Once the correct compensation values are found these will be stored and used to compensate each CAP pin. If the SX8646 is shut down the compensation values will be lost next power-up the procedure starts all over again. This assures that the SX8646 will operate under any condition. Powering up at e.g. different temperatures will not change the performance of the SX8646 and the host does not have to do anything special ...
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... Figure 13 shows the building blocks used for configuring the SX8646. The default configuration parameters of the SX8646 are stored in the Quick Start Memory (QSM). This configuration data is setup to a very common application for the SX8646 with eight buttons. Without any programming or host interaction the SX8646 will startup in the Quick Start Application. ...
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... The content of the SPM remains valid as long as the SX8646 is powered and no reset is performed. After a power down or reset the host needs to re-write the SPM if relevant for the application. ...
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... The writing of the host towards the NVM is not done directly but done in 2 steps (Figure 15). In the first step the host writes to the SPM (as in Figure 14). In the second step the host signals the SX8646 to copy the SPM content into the NVM. ...
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... As soon as the INTB rises the SX8646 will be ready for I2C communication. 3.14.2 RESETB When RESETB is driven low the SX8646 will reset and start the power up sequence as soon as RESETB is driven high or pulled high. In case the user does not require a hardware reset control pin then the RESETB pin can be connected to VDD. ...
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... Software Reset To perform a software reset the host needs to write 0xDE followed by 0x00 at the SoftReset register at address 0xB1. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Software Reset Figure 18 © 2010 Semtech Corp. 21 SX8646 DATASHEET www.semtech.com ...
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... During power up the INTB is kept low. Once the power up sequence is terminated the INTB is released autonomously. The SX8646 is then ready for operation. During the power on period the SX8646 stabilizes the internal regulators, RC clocks and the firmware initializes all registers. During the power up the SX8646 is not accessible and I2C communications are forbidden. ...
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... Example A typical example of the assertion and clearing of the INTB and the I2C communication is shown in Figure 20. When a button is touched the SX8646 will assert the interrupt (1). The host will read the IrqSrc information over the I2C and this clears the interrupt (2). If the finger releases the button the interrupt will be asserted (3). The host reading the IrqSrc information will clear the interrupt (4) ...
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... Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers GpioMode GpioPullUpDown GpioInterrupt GpioDebounce IrqSrc[4] GpiStat SPM/I2C Parameters Applicable in GPI Mode LED control in GPP mode Figure 23 © 2010 Semtech Corp. 24 SX8646 DATASHEET GPI www.semtech.com ...
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... Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers GpioMode GpioOutPwrUp GpioPolarity GpioIntensityOn GpioIntensityOff GpioFunction GppPinId GppIntensity SPM/I2C Parameters Applicable in GPP Mode Autolight ON (mapped to Button) © 2010 Semtech Corp. 25 DATASHEET GPP Autolight OFF www.semtech.com SX8646 ...
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... Please note that standard high/low logic signals are just a specific case of GPO mode and can also be generated simply by setting inc/dec time to 0 (ie OFF) and programming intensity OFF/ON to 0x00 and 0xFF. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers © 2010 Semtech Corp. 26 SX8646 DATASHEET www.semtech.com ...
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... Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers GpioMode GpioOutPwrUp GpioAutoligth GpioPolarity GpioIntensityOn GpioIntensityOff GpioFunction GpioIncFactor GpioDecFactor GpioIncTime GpioDecTime GpioOffDelay GpoCtrl SPM/I2C Parameters Applicable in GPO Mode © 2010 Semtech Corp. 27 SX8646 DATASHEET GPO ...
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... Semtech Corp. 28 SX8646 DATASHEET Index Lin/Log Index Lin/Log Index 160 161/81 192 193/125 224 161 162/82 193 194/127 225 162 163/83 194 ...
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... ADVANCED COMMUNICATIONS & SENSING 3.17 Smart Wake Up The SX8646 offers a smart wake up mechanism which allows waking-up from the Doze low power mode to the Active mode in a secure/controlled way and not by any unintentional sensor activation. Until the full correct wake-up sequence is entered, the SX8646 will remain in Doze mode. Any wrong key implies the whole sequence to be entered again ...
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... ADVANCED COMMUNICATIONS & SENSING DESCRIPTIONS 4.1 Introduction This chapter describes briefly the pins of the SX8646, the way the pins are protected, if the pins are analog, digital, require pull up or pull down resistors and show control signals if these are available. 4.2 ASI pins CAP0, CAP1, ..., CAP7 The capacitance sensor pins (CAP0, CAP1, ...
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... Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers SX8646 VANA CP VANA CN Simplified diagram of CN and CP Figure 31 VDD SX8646 R_INT INTB Simplified diagram of INTB Figure 32 © 2010 Semtech Corp. 31 SX8646 DATASHEET ASI INT www.semtech.com ...
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... Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers VDD SX8646 SCL Simplified diagram of SCL Figure 33 VDD SX8646 SDA Simplified diagram of SDA Figure 34 © 2010 Semtech Corp. 32 SX8646 DATASHEET SCL_IN SDA_IN SDA_OUT www.semtech.com ...
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... Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers VDD SX8646 RESETB Simplified diagram of RESETB controlled by host VDD SX8646 RESETB Simplified diagram of RESETB without host control © 2010 Semtech Corp. 33 SX8646 DATASHEET RESETB_IN RESETB_IN www.semtech.com ...
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... VDD has protection to GROUND. Figure 37 shows a simplified diagram of the VDD pin. GND The SX8646 has four ground pins all named GND. These pins and the package center pad need to be connected to ground potential. The GND has protection to VDD. Figure 38 shows a simplified diagram of the GND pin. ...
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... ADVANCED COMMUNICATIONS & SENSING VANA, VDIG The SX8646 has on-chip regulators for internal use (pins VANA and VDIG). VANA and VDIG have protection to VDD and to GND. The output of the regulators needs to be de-coupled with a small 100nF capacitor to ground. Figure 39 shows a simplified diagram of the VANA and VDIG pin. ...
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... C ETAILED ONFIGURATION DESCRIPTIONS 5.1 Introduction The SX8646 configuration parameters are taken from the QSM or the NVM and loaded into the SPM as explained in the chapter ‘functional description’. This chapter describes the details of the configuration parameters of the SX8646. . The SPM is split by functionality into 5 configuration sections: • ...
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... SPM address map: 0x00…0x3F Table 12 © 2010 Semtech Corp. 37 SX8646 DATASHEET Name Reserved BtnCfg BtnAvgThresh BtnCompNegThresh BtnCompNegCntMax BtnHysteresis BtnStuckAtTimeout Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved ...
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... SPM address map: 0x40…0x7F Table 13 © 2010 Semtech Corp. 38 SX8646 DATASHEET Name default QSM value GpioDecTime1_0 0x44 GpioOffDelay7_6 0x00 GpioOffDelay5_4 0x00 GpioOffDelay3_2 0x00 GpioOffDelay1_0 0x00 GpioPullUpDown7_4 0x00 ...
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... Doze Mode Scan Period (Figure 7) 0x00: Reserved 0x01: 15ms … 0x0D: 195ms (default) … 0xFF: 255 x 15ms Passive Timer on Button Information (Figure 8) 0x00: OFF (default) 0x01: 1 second … 0xFF: 255 seconds General Parameters Table 14 © 2010 Semtech Corp. 39 SX8646 DATASHEET www.semtech.com ...
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... CAP3 Touch Threshold CAP4 Touch Threshold CAP5 Touch Threshold CAP6 Touch Threshold CAP7 Touch Threshold Reserved Reserved Reserved Reserved © 2010 Semtech Corp. 40 SX8646 DATASHEET Reserved: ‘01’ Defines the mode of Default Button the CAP pin. Button 00: Disabled 01: Button Button 10: Reserved ...
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... Periodic Offset Compensation Capacitive Sensors Parameters Table 15 minimum default one eight CAP pin modes Table 16 Possible © 2010 Semtech Corp. 41 SX8646 DATASHEET Defines the periodic offset compensation. 0x0: OFF (default) 0x1: 1 second 0x2: 2 seconds … 0x7: 7 seconds 0x8: 16 seconds 0x9: 18 seconds … ...
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... Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Button examples Figure 41 Approximate Sensitivity Maximum Tick Level 0 1000 1 2000 2 3000 3 4000 4 5000 5 6000 6 7000 7 8000 ASI Maximum Tick Levels Table 17 © 2010 Semtech Corp. 42 SX8646 DATASHEET www.semtech.com ...
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... CapThresh0, CapThresh1, CapThresh2, CapThresh3, CapThresh4, CapThresh5, CapThresh6, CapThresh7: For each CAP pin a threshold level can be set individually. The threshold levels are used by the SX8646 for making touch and release decisions on e.g. touch or no- touch. The details are explained in the sections for buttons. ...
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... Defines the button hysteresis corresponding to a percentage of the CAP thresholds (defined in Table 18). 0x00: 0% … 0x0A: 10% (default) … 0x64: 100% All buttons use the same hysteresis Defines the stuck at timeout. 0x00: OFF (default) © 2010 Semtech Corp. 44 SX8646 DATASHEET www.semtech.com ...
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... The release is detected immediately (BtnCfg [3:2] = 00) at the first sample which is below the threshold minus the hysteresis. BtnCfg The SX8646 can report all touches of multiple fingers or the SX8646 can be set to report only the first detected touch. In the later case all succeeding touches are ignored. The very first touch should be released before a next touch will be detected. ...
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... BtnAvgThresh. This mechanism avoids that a valid touch will be averaged and finally the tick difference becomes zero. In case three or more sensors reach the BtnAvgThresh value simultaneously then the SX8646 will start an offset compensation procedure. Small environmental and system noise cause the ticks to vary slowly around the zero idle mode value. ...
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... After the actual finger release the button can be touched again and will be reported as usual. In case the stuckat timer is not required it can be set to zero. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers © 2010 Semtech Corp. 47 SX8646 DATASHEET www.semtech.com ...
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... Defines Group0 sensor events: 0: OFF (default any of the enabled sensor events occurs the Group0 event will occur as well. All sensors events within the group can be independently set. Defines Group1 sensor events: 0: OFF (default www.semtech.com SX8646 ...
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... Touch Autolight Mapping, Sensor Information © 2010 Semtech Corp. 49 DATASHEET If any of the enabled sensor events occurs the Group0 event will occur as well. All sensors events within the group can be independently set. and the sensor information which GPO OFF Release www.semtech.com SX8646 ...
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... GPIO[4] Output Polarity GPIO[3] Output Polarity GPIO[2] Output Polarity GPIO[1] Output Polarity GPIO[0] Output Polarity 7:0 ON Intensity Index © 2010 Semtech Corp. 50 SX8646 DATASHEET Defines the GPIO mode. 00: GPO (default) 01: GPP 10: GPI 11: Reserved Defines the values of GPO and GPP pins after power up ie default values of I2C parameters GpoCtrl and GppIntensity respectively ...
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... GPIO[4] Fading Decrement Factor GPIO[3] Fading Decrement Factor GPIO[2] Fading Decrement Factor GPIO[1] Fading Decrement Factor GPIO[0] Fading Decrement Factor 7:4 GPIO[7] Fading Increment Time © 2010 Semtech Corp. 51 SX8646 DATASHEET … 0xFF: 255 (default) Defines the OFF intensity index 0x00: 0 (default) 0x01: 1 … ...
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... GPIO[0] Pullup/down 7:6 GPI[7] Interrupt 5:4 GPI[6] Interrupt 3:2 GPI[5] Interrupt 1:0 GPI[4] Interrupt 7:6 GPI[3] Interrupt 5:4 GPI[2] Interrupt 3:2 GPI[1] Interrupt © 2010 Semtech Corp. 52 SX8646 DATASHEET 0x0: OFF (default) 0x1: 0.5ms 0x2: 1ms … 0xF: 7.5ms The total fading in time will be: GpioIncTime*GpioIncFactor* (GpioIntensityOn – GpioIntensityOff) Defines the fading decrement time ...
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... GPI[2] Debounce GPI[1] Debounce GPI[0] Debounce GPIO Parameters Table 21 GPI Applicable SPM/I2C Parameters vs. GPIO Mode © 2010 Semtech Corp. 53 SX8646 DATASHEET Enables the GPI debounce (done on 10 consecutive samples at 1ms OFF (default GPP GPO ...
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... After the start condition [S], the slave address (SA) is sent, followed by an eighth bit (‘0’) indicating a Write. The SX8646 then Acknowledges [A] that it is being addressed, and the Master sends an 8 bit Data Byte consisting of the SX8646 Register Address (RA). The Slave Acknowledges [A] and the master sends the appropriate 8 bit Data Byte (WD0) ...
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... The SX8646 responds with an Acknowledge [A] and the read Data byte (RD0). If the master needs to read more data it will acknowledge [A] and the SX8646 will send the next read byte (RD1). This sequence can be repeated until the master terminates with a NACK [N] followed by a stop [P]. ...
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... Reserved SpmKeyMsb read/write SpmkeyLsb read/write SoftReset read/write I2C Registers Overview Table 23 © 2010 Semtech Corp. 56 SX8646 DATASHEET Description Interrupt Source Button Status LSB GPI Status SPM Status Compensation and Operating Mode GPO Control GPP Pin Selection GPP Intensity SPM Configuration ...
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... Buttons interrupt flag 1 Compensation interrupt flag 0 Operating Mode interrupt flag Interrupt Source Table 24 © 2010 Semtech Corp. 57 SX8646 DATASHEET Interrupt source flags 0: Inactive (default) 1: Active INTB goes low if any of these bits is set. More than one bit can be set. Reading IrqSrc clears it together with INTB ...
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... Once – NVM is used if NvmValid = 1, else QSM. NvmCount 2: Twice – NVM is used if NvmValid = 1, else QSM. 3: Three times – NVM is used if NvmValid = 1, else QSM. 4: More than three times – QSM is used I2C SPM status Table 27 © 2010 Semtech Corp. 58 SX8646 DATASHEET www.semtech.com ...
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... I2C compensation, operation modes Bits Description Triggers ON/OFF state of GPOs when Autolight is OFF 0: OFF ( IntensityOff) 7:0 GpoCtrl[7: ( IntensityOn) Default is set by SPM parameter GpioOutPwrUp Bits of non-GPO pins are ignored. I2C GPO Control Table 29 © 2010 Semtech Corp. 59 SX8646 DATASHEET www.semtech.com ...
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... Reading returns the intensity index of the GPP pin selected in GppPinId. Default value is IntensityOn or IntensityOff depending on GpioOutPwrUp. I2C GPP Intensity Table 31 Description Writing 0xDE followed by 0x00 will reset the chip. Soft Reset Table 32 I2C © 2010 Semtech Corp. 60 SX8646 DATASHEET www.semtech.com ...
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... ADVANCED COMMUNICATIONS & SENSING 6.6 SPM Gateway Registers The SX8646 I2C interface offers two registers for exchanging the SPM data with the host. • SpmCfg • SpmBaseAddr Address Name 0x0D SpmCfg Address Name 0x0E SpmBaseAddr The exchange of data, read and write, between the host and the SPM is always done in bursts of eight bytes. ...
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... IrqSrc[5] set. In Sleep mode the SPM write can be actually applied with a delay of 30ms. The host clears the interrupt and IrqSrc[5] by reading the IrqSrc register. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Figure 46: SPM Write Sequence © 2010 Semtech Corp. 62 SX8646 DATASHEET www.semtech.com ...
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... The complete SPM can be read by repeating 16 times the cycles shown in Figure 47 using base addresses 0x00, 0x08, 0x10, …, 0x70, 0x78. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Figure 47: SPM Read Sequence © 2010 Semtech Corp. 63 SX8646 DATASHEET www.semtech.com ...
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... Figure 48 shows the simplified diagram of the NVM counter. The SX8646 is delivered with empty NVM and NvmCount set to zero. The SPM points to the QSM. Each NVM burn will increase the NvmCount. At the fourth NVM burn the SX8646 switches definitely to the QSM. The burning of the SPM into the NVM is done by executing a special sequence of four I2C commands. ...
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... ADVANCED COMMUNICATIONS & SENSING PPLICATION NFORMATION A typical application schematic is shown in Figure 50. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers Typical Application Figure 50 © 2010 Semtech Corp. 65 SX8646 DATASHEET www.semtech.com ...
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... ADVANCED COMMUNICATIONS & SENSING ACKAGING NFORMATION 8.1 Package Outline Drawing SX8646 is assembled in a MLPQ-UT28 package as shown in Figure 51. 8.2 Land Pattern The land pattern of MLPQ-UT28 package shown in Figure 52. Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers ...
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... Semtech Corporation Advanced Communications and Sensing Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 Revision 7_4, February 10 Ultra Low Power, Capacitive Button Touch Controller (8 sensors) with Enhanced LED Drivers © 2010 Semtech Corp. 67 SX8646 DATASHEET www.semtech.com ...