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Hi Everyone,   To complete the collection of simple bare-metal examples for the Xtrinsic sensors on the FRDM-FXS-MULTI(-B) sensor expansion board, I would like to share here another example code/demo I have created for the MPL3115A2 pressure sensor.   This example illustrates: 1. Initialization of the MKL25Z128 MCU (mainly I2C and PORT modules). 2. I2C data write and read operations. 3. Initialization of the MPL3115A2. 4. Output data reading using an interrupt technique. 5. Conversion of the output values from registers 0x01 – 0x05 to real values in Pascals and °C. 6. Visualization of the output values in the FreeMASTER tool.   1. As you can see in the FRDM-FXS-MULTI(-B)/FRDM-KL25Z schematics and the image below, I2C signals are routed to the I2C1 module (PTC1 and PTC2 pins) of the KL25Z MCU and the INT1 output (INT_PED) is connected to the PTA13 pin ( make sure that pins 2-3 of J5 on the sensor board are connected together using a jumper ). The INT1 output of the MPL3115A2 is configured as a push-pull active-low output, so the corresponding PTA13 pin configuration is GPIO with an interrupt on falling edge.     The MCU is, therefore, configured as follows. void MCU_Init ( void ) {      //I2C1 module initialization      SIM_SCGC4 |= SIM_SCGC4_I2C1_MASK;        // Turn on clock to I2C1 module      SIM_SCGC5 |= SIM_SCGC5_PORTC_MASK;       // Turn on clock to Port C module      PORTC_PCR1 |= PORT_PCR_MUX(0x2);         // PTC1 pin is I2C1 SCL line      PORTC_PCR2 |= PORT_PCR_MUX(0x2);         // PTC2 pin is I2C1 SDA line      I2C1_F  |= I2C_F_ICR(0x14);              // SDA hold time = 2.125us, SCL start hold time = 4.25us, SCL stop hold time = 5.125us      I2C1_C1 |= I2C_C1_IICEN_MASK;            // Enable I2C1 module                    //Configure the PTA13 pin (connected to the INT1 of the MPL3115A2) for falling edge interrupts      SIM_SCGC5 |= SIM_SCGC5_PORTA_MASK;       // Turn on clock to Port A module      PORTA_PCR13 |= (0|PORT_PCR_ISF_MASK|     // Clear the interrupt flag                        PORT_PCR_MUX(0x1)|     // PTA5 is configured as GPIO                        PORT_PCR_IRQC(0xA));   // PTA5 is configured for falling edge interrupts                   //Enable PORTA interrupt on NVIC      NVIC_ICPR |= 1 << (( INT_PORTA - 16)%32);      NVIC_ISER |= 1 << (( INT_PORTA - 16)%32); }   2. The 7-bit I 2 C address of the MPL3115A2 is fixed value 0x60 which translates to 0xC0 for a write and 0xC1 for a read. As shown above, the SCL line is connected to the PTC1 pin and SDA line to the PTC2 pin. The I2C clock frequency is 125 kHz. The screenshot below shows the write operation which writes the value 0x39 to the CTRL_REG1 register (0x26).     And here is the single byte read from the WHO_AM_I register (0x0C). As you can see, it returns the correct device ID 0xC4.     Multiple bytes of data can be read from sequential registers after each MPL3115A2 acknowledgment (AK) is received until a no acknowledge (NAK) occurs from the KL25Z followed by a stop condition (SP) signaling an end of transmission. A burst read of 5 bytes from registers 0x01 to 0x05 is shown below. It also shows how the INT1 pin is automatically deasserted by reading the output registers.       3. At the beginning of the initialization, all MPL3115A2 registers are reset to their default values by setting the RST bit of the CTRL_REG1 register. The DRDY interrupt is enabled and routed to the INT1 pin that is configured to be a push-pull, active-low output. Further, the OSR ratio of 128 is selected and finally the part goes into Active barometer (eventually altimeter) mode.   void MPL3115A2_Init ( void ) {      I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0x04);          // Reset all registers to POR values            Pause(0x631);          // ~1ms delay            I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, PT_DATA_CFG_REG, 0x07);    // Enable data flags      I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG3, 0x00);          // Push-pull, active low interrupt      I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG4, 0x80);          // Enable DRDY interrupt      I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG5, 0x80);          // DRDY interrupt routed to INT1 - PTA13      I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0x39);          // Active barometer mode, OSR = 128              //I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0xB9);        // Active altimeter mode, OSR = 128 }   4. In the ISR, only the interrupt flag is cleared and the DataReady variable is set to indicate the arrival of new data.   void PORTA_IRQHandler () {      PORTA_PCR13 |= PORT_PCR_ISF_MASK;          // Clear the interrupt flag      DataReady = 1;   }   5. In the main loop, the DataReady variable is periodically checked and if it is set, both pressure (eventually altitude) and temperature data are read and then calculated.   if (DataReady)          // Is a new set of data ready? {      DataReady = 0;                                                                                                                          I2C_ReadMultiRegisters(MPL3115A2_I2C_ADDRESS, OUT_P_MSB_REG, 5, RawData);          // Read data output registers 0x01-0x05                     /* Get pressure, the 20-bit measurement in Pascals is comprised of an unsigned integer component and a fractional component.      The unsigned 18-bit integer component is located in RawData[0], RawData[1] and bits 7-6 of RawData[2] .      The fractional component is located in bits 5-4 of RawData[2] . Bits 3-0 of RawData[2] are not used.*/                                              Pressure = ( float ) (((RawData[0] << 16) | (RawData[1] << 😎 | (RawData[2] & 0xC0)) >> 6) + ( float ) ((RawData[2] & 0x30) >> 4) * 0.25;                                                  /* Get temperature, the 12-bit temperature measurement in °C is comprised of a signed integer component and a fractional component.      The signed 8-bit integer component is located in RawData[3] .      The fractional component is located in bits 7-4 of RawData[4] . Bits 3-0 of OUT_T_LSB are not used. */                          Temperature = ( float ) (( short )((RawData[3] << 😎 | (RawData[4] & 0xF0)) >> 4) * 0.0625;                              /* Get altitude, the 20-bit measurement in meters is comprised of a signed integer component and a fractional component.      The signed 16-bit integer component is located in RawData[0] and RawData[1] .      The fraction component is located in bits 7-4 of RawData[2] . Bits 3-0 of RawData[2] are not used */                                        //Altitude = (float) ((short) ((RawData[0] << 😎 | RawData[1])) + (float) (RawData[2] >> 4) * 0.0625; }   6. The calculated values can be watched in the "Variables" window on the top right of the Debug perspective or in the FreeMASTER application. To open and run the FreeMASTER project, install the FreeMASTER 1.4 application and FreeMASTER Communication Driver.       Attached you can find the complete source code written in the CW for MCU's v10.5 including the FreeMASTER project. If there are any questions regarding this simple application, do not hesitate to ask below. Your feedback or suggestions are also welcome.   Regards, Tomas Original Attachment has been moved to: FreeMASTER---FRDM-KL25Z-MPL3115A2-Pressure-and-temperature-reading-using-I2C-and-interrupt.zip Original Attachment has been moved to: FRDM-KL25Z-MPL3115A2-Pressure-and-temperature-reading-using-I2C-and-interrupt.zip
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Here is the Installer file for the revision 4.2.0.8 of the Sensor Toolbox GUI
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  LGA 8 PACKAGE 5.0 mm x 3.0 mm x 1.1 mm  
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Hi, The MPL3115A2, provides highly accurate pressure and altitude data with variable sampling rate capability. It has very low-power consumption, smart features and requires zero data processing, it is ideal for mobile devices, medical and security applications. Here is a Render of the MPL3115A2 Breakout- Board downloaded from OSH Park: And here is an image of the Layout Design for this board: In the Attachments section, you can find the Schematic Source File (.SCH), Schematic PDF File, Layout Source File (BRD), Gerber Files (GTL, GBL, GTS, GBS, GTO, GBO, GKO, XLN) and BOM for this Breakout-board. If you are interested in more designs like this breakout board for other sensors, please go to Freescale Sensors Breakout Boards Designs – HOME
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Our pressure sensors are designed to be used with clean, dry air only. However, most of our customers ran their own tests to determine if the response of the sensor would be appropriated for their specific applications. I personally ran a test with an MPXV5700AP directly exposed to car coolant @25°C and 100PSI, zero failure was detected for almost a month. See attached .xlsx for detailed information. The error of the sensor was calculated comparing the output of the sensor with a mechanical manometer, however this was only an approximation since the mechanical manometer was used as the "true pressure value". In this kind of applications, we would recommend to use Parker O-lube silicone grease or DMS-T46 or T51. This type of grease is used by most of our customer without problems. In fact the basic recommendations are to use a silicone oil (or preferably grease) with high viscosity and high molecular weight. In this case the size of the molecules are big enough to limit the penetration of the grease inside our protective silicone gel which is over the die. In terms of contaminants, the silicon grease must be free of halogenures (Cl content < 50 ppm) to reduce the risk of bond pad corrosion. On the other hand, don't forget that whatever the material you will use, as soon as you put something on our gel you have a high probability to see some offset drift. This is coming from additional mechanical stress and/or gel swelling. The amount of gel and global mechanical design are usually also part of the offset drift.
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My friend Matt Muddiman of Freescale gave this presentation as part of the MEMS Education Series (hosted by Arizona Technology Council and MEMS Industry Group) in Scottsdale Arizona earlier this week.
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This time, I would like to share with you an example project using the MPL115A1, the NXP digital barometer.   The MPL115A1 is a simple barometer with digital output for cost-effective applications. It employs a MEMS pressure sensor with a conditioning integrated circuit to provide accurate pressure data. An integrated analog-to-digital converter (ADC) provides digitized temperature and pressure sensor outputs via serial peripheral interface (SPI), with bus speeds up to 8 Mbps.   You may find more information at: MPL115A: 50 to 115kPa, Absolute Digital Pressure Sensor.   I created this project using the FRDM-KL25Z platform and the MPL115A1 absolute digital pressure sensor. The complete source code is written in KDS IDE. You may find the complete project attached to this post.   This document gives you an introduction of the MPL115A1 pressure sensor as well as the different configurations and guides you through the initialization process and how to appreciate the demonstration.   Introduction to the example project This example is based on the application note AN3785 -How to Implement the Freescale MPL115A Digital Barometer. I recommend using it as a reference.   Through this example project, the MCU is configured to use the SPI interface and the PIT module. The local pressure is read every second.   There are MPL115A1 SPI commands to read coefficients, execute Pressure and Temperature conversions, and to read Pressure and Temperature data. The sequence of the commands for the interaction is given as an example to operate the MPL115A1. Initialization of the MKL25Z128 MCU.   Sequence flow chart. The MPL115A1 interfaces to a host (or system) microcontroller in the user’s application. All communications are via SPI. A typical usage sequence is as follows: Every stage of the flow chart is applied on this example and explained below.   Reading coefficient data These are MPL115A2 SPI commands to read coefficients. The coefficients are usually stored in the host microcontoller local memory but can be re-read at any time.   Reading of the coefficients may be executed only once and the values stored in the host microcontroller. It is not necessary to read this multiple times because the coefficients within a device are constant and do not change.   Read Coefficients: [CS=0], [0x88], [0x00], [0x8A], [0x00], [0x8C], [0x 00], [0x8E], [0x00], [0x90], [0x00], [0x92], [0x00], [0x94], [0x00], [0x96], [0x00], [0x00], [CS=1] Once the coefficients are obtained, they are computed inside the MPL115A1_Read_Preassure function .     Data conversion This is the MPL115A2 SPI commands to start conversion.   This is the first step that is performed each time a new pressure reading is required which is initiated by the host sending the CONVERT command. The main system circuits are activated (wake) in response to the command and after the conversion completes, the result is placed into the Pressure and Temperature ADC output registers.   Start conversion: [CS=0], [0x24], [0x00], [CS=1], [13 ms Delay]     This is the MPL115A2 SPI commands to read raw temperature and pressure data.     Start Read raw data: [CS=0], [0x80], [0x00], [0x82], [0x00], [0x84], [0x00,] [0x86], [0x00], [0x00], [CS=1]   Compensated pressure reading Once the raw rata is obtained, the compensation procedure is applied as follow:     Local pressure   Once the steps mentioned above are followed, the MPL115A1_Read_Preassure function returns the local pressure value into the local_pressure variable. I recommend evaluating this variable in order to know the final result.     I hope you find the information useful and funny.   Regards, David  
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Hello community, As continuation of the Different pin styles in pressure sensors post, I would like to add some useful information about the pin styles mentioned on the datasheets. Some pressure sensors shows the following pin style configuration: But… What do V1, V2 and VEx actually mean? How should I connect those pins? Answer: V1, V2 and VEX pins are used for factory trimming and it is recommended to leave these pins unconnected. So, in case of unibody package, you will require only pin #1 (Vout) , pin #2 (Ground) , and pin #3 (Vs) as follow: I hope you find useful this information. Regards, David
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Hi Everyone, I would like to share here one of my examples I created for the MPL3115A2 while working with the NXP FRDM-KL25Z platform and FRDMSTBC-P3115 shield board. It illustrates the use of the embedded FIFO buffer to collect either pressure/temperature or altitude/temperature data that are read from the FIFO using an interrupt technique through the I2C interface. The FIFO is set to store the maximum number of samples (32). Each sample consists of 3 bytes of pressure (or altitude) data and 2 bytes of temperature data. Therefore 160 bytes (32 x (3 + 2)) in total are read from the FIFO when the FIFO is full and the FIFO interrupt is asserted. The MPL3115A2  is initialized as follows. / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * MPL3115A2 initialization function * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * void MPL3115A2_Init ( void ) { I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG1 , 0x04 ) ; // Reset all registers to POR values Pause ( 0x631 ) ; // ~1ms delay I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , F_SETUP_REG , 0xA0 ) ; // FIFO Fill mode, 32 samples I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG4 , 0x40 ) ; // Enable FIFO interrupt I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG5 , 0x40 ) ; // Route the FIFO interrupt to INT1 - PTA5 I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG2 , 0x00 ) ; // Time step = ~1s I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG3 , 0x00 ) ; // Push-pull, active low interrupt I2C_WriteRegister ( MPL3115A2_I2C_ADDRESS , CTRL_REG1 , 0x39 ) ; // Active barometer mode, OSR = 128 //I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0xB9); // Active altimeter mode, OSR = 128 } ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ In the ISR, only the interrupt flag is cleared and the FIFO_DataReady variable is set to indicate that the FIFO is full. /****************************************************************************** * PORT A Interrupt handler ******************************************************************************/ void PORTA_IRQHandler ( ) { PORTA_PCR5 | = PORT_PCR_ISF_MASK ; FIFO_DataReady = 1 ; } ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ Once the FIFO_DataReady variable is set, the STATUS register (0x00) is read to clear the FIFO interrupt status bit and deassert the INT1 pin. Afterwars the FIFO is read using a 160-byte (5 x 32 bytes) burst read starting from the OUT_P_MSB register (0x01). Then the raw pressure (or altitude) and temperature data are converted to real values. if ( FIFO_DataReady ) { FIFO_DataReady = 0 ; FIFO_Status = I2C_ReadRegister ( MPL3115A2_I2C_ADDRESS , STATUS_REG ) ; // Read the Status register to clear the FIFO interrupt status bit I2C_ReadMultiRegisters ( MPL3115A2_I2C_ADDRESS , OUT_P_MSB_REG , 5 * Watermark_Val , RawData ) ; // Read the FIFO using a burst read for ( i = 0 ; i < Watermark_Val ; i ++ ) { /* Get pressure, the 20-bit measurement in Pascals is comprised of an unsigned integer component and a fractional component. The unsigned 18-bit integer component is located in OUT_P_MSB, OUT_P_CSB and bits 7-6 of OUT_P_LSB. The fractional component is located in bits 5-4 of OUT_P_LSB. Bits 3-0 of OUT_P_LSB are not used. */ Pressure [ i ] = ( float ) ( ( ( RawData [ 0 + i * 5 ] << 16 ) | ( RawData [ 1 + i * 5 ] << 8 ) | ( RawData [ 2 + i * 5 ] & 0xC0 ) ) >> 6 ) + ( float ) ( ( RawData [ 2 + i * 5 ] & 0x30 ) >> 4 ) * 0.25 ; /* Get temperature, the 12-bit temperature measurement in °C is comprised of a signed integer component and a fractional component. The signed 8-bit integer component is located in OUT_T_MSB. The fractional component is located in bits 7-4 of OUT_T_LSB. Bits 3-0 of OUT_T_LSB are not used. */ Temperature [ i ] = ( float ) ( ( short ) ( ( RawData [ 3 + i * 5 ] << 8 ) | ( RawData [ 4 + i * 5 ] & 0xF0 ) ) >> 4 ) * 0.0625 ; /* Get altitude, the 20-bit measurement in meters is comprised of a signed integer component and a fractional component. The signed 16-bit integer component is located in OUT_P_MSB and OUT_P_CSB. The fraction component is located in bits 7-4 of OUT_P_LSB. Bits 3-0 of OUT_P_LSB are not used */ //Altitude[i] = (float) ((short) ((RawData[0 + i*5] << 8) | RawData[1 + i*5])) + (float) (RawData[2 + i*5] >> 4) * 0.0625; } } ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ Deassertion of the INT1 pin after reading the STATUS register (0x00). The auto acquisition time step is set in this example to the lowest possible value (1s), so the FIFO is read every ~32s. The calculated values can be watched in the "Variables" window on the top right of the Debug perspective. Attached you can find the complete source code. If there are any questions regarding this simple example project, please feel free to ask below. Your feedback or suggestions are also welcome.   Regards, Tomas
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SOP Top Side Port Package_1369-01  
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Hello Freescale Community, Most of the new Freescale Sensors in our portfolio come in very small packages , s ome of them as small as 2x2x1mm, which is awesome! However, one of the problems that we detected last year is that many customers struggle in the evaluation stage of the project due to the small packages. They should either, buy an evaluation board or spend valuable time designing and manufacturing a PCB just for testing our devices. Our goal with this project is to share with our community the Freescale Sensors Breakout Boards we designed for this specific purpose, so you can easily manufacture your own sensor boards or modify our designs to fit  your specific application. This way you can easily evaluate Freescale sensors. The boards were designed to be used in a prototype board (DIP style pins) and they can communicate to any MCU thru IIC or SPI (depending on the sensor). These designs were made using Eagle Layout 6.5, if you want to modify the designs you can do it with the free version of Eagle CAD (for non-commercial purposes), or you can send the gerber files (included in the zip files) to your preferred PCB manufacturer. The following designs are available: + Altimeter: MPL3115A2 Breakout Board + Accelerometer: MMA845x Breakout Board MMA865x Breakout Board MMA8491 Breakout Board FXLN83xx Breakout Board FXLS8471 Breakout Board MMA690x Breakout Board + Accelerometer + Magnetometer (6-DOF): FXOS8700 Breakout Board + Gyroscope: FXAS2100x Breakout Board The above .ZIP files, contains the following design information: - Schematic Source File (.SCH) - Schematic (.PDF) - Layout Source File (.BRD) - Layout Images (.jpg) - Gerber Files (GTL, GBL, GTS, GBS, GTO, GBO, GKO, XLN). - PCB Render Image (.png created in OSH park) - BOM (.xls) Additional content: If you want to modify our designs, please download the attached library file "Freescale_Sensors_v2.lbr" and add it to your Eagle Library repository. We'll be more than glad to respond to your questions and please, let us know what you think. -Freescale Sensor's Support team.
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Hi Everyone,   I would like to share a simple example code/demo that reads both the altitude and temperature data from the Xtrinsic MPL3115A2 pressure sensor and visualizes them using the FreeMASTER tool via USBDM interface. I have used recently released Xtrinsic MEMS sensors board that features three types of Xtrinsic sensors including the MPL3115A2 and is fully compatible with the Freescale FRDM-KL25Z platform.   According to the User Manual, both interrupt pins of the MPL3115A2 are connected to the PTD3 pin of KL25Z MCU through a 4.7K pull-up resistor as well as both SCL and SDA lines that are connected to the I2C1 module (PTE1 and PTE0 pins) on the KL25Z. The MCU is, therefore, configured as follows: void MCU_Init ( void ) {        //I2C1 module initialization            SIM_SCGC4 |= SIM_SCGC4_I2C1_MASK;        // Turn on clock to I2C1 module        SIM_SCGC5 |= SIM_SCGC5_PORTE_MASK;       // Turn on clock to Port E module        PORTE_PCR1 = PORT_PCR_MUX(6);            // PTE1 pin is I2C1 SCL line        PORTE_PCR0 = PORT_PCR_MUX(6);            // PTE0 pin is I2C1 SDA line        I2C1_F  = 0x14;                          // SDA hold time = 2.125us, SCL start hold time = 4.25us, SCL stop hold time = 5.125us        I2C1_C1 = I2C_C1_IICEN_MASK;             // Enable I2C1 module          //Configure the PTD3 pin (connected to the INT2 of the MPL3115A2) for falling edge interrupt          SIM_SCGC5 |= SIM_SCGC5_PORTD_MASK;       // Turn on clock to Port D module        PORTD_PCR3 |= (0|PORT_PCR_ISF_MASK|      // Clear the interrupt flag        PORT_PCR_MUX(0x1)|                       // PTD3 is configured as GPIO        PORT_PCR_IRQC(0xA));                     // PTD3 is configured for falling edge interrupts                     //Enable PORTD interrupt on NVIC        NVIC_ICPR |= 1 << (( INT_PORTD - 16)%32);        NVIC_ISER |= 1 << (( INT_PORTD - 16)%32); }   In the ISR, only the interrupt flag is cleared and the DataReady variable is set to indicate the arrival of new data.   void PORTD_IRQHandler () {        PORTD_PCR3 |= PORT_PCR_ISF_MASK;         // Clear the interrupt flag        DataReady = 1; } At the beginning of the initialization, all MPL3115A2 registers are reset to their default values by setting the RST bit of the CTRL_REG1 register.The DRDY interrupt is enabled and routed to the INT2 pin that is configured to be an open-drain, active-low output. During the initialization of the MPL3115A2, the OSR ratio of 128 is selected and finally the part goes into Active Altimeter mode.   void MPL3115A2_Init ( void ) {        unsigned char reg_val = 0;                    I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0x04);                        // Reset all registers to POR values             do             // Wait for the RST bit to clear        {           reg_val = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1) & 0x04;        }  while (reg_val);        I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, PT_DATA_CFG_REG, 0x07);                  // Enable data flags        I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG3, 0x11);                        // Open drain, active low interrupts        I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG4, 0x80);                        // Enable DRDY interrupt        I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG5, 0x00);                        // DRDY interrupt routed to INT2 - PTD3        I2C_WriteRegister(MPL3115A2_I2C_ADDRESS, CTRL_REG1, 0xB9);                        // Active altimeter mode, OSR = 128 }   In the main loop, the DataReady variable is periodically checked and if it is set, both altitude and temperature data are read and then calculated.   if (DataReady)          // Is a new set of data ready? {                   DataReady = 0;                  OUT_P_MSB = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, OUT_P_MSB_REG);        // High byte of integer part of altitude,        OUT_P_CSB = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, OUT_P_CSB_REG);        // Low byte of integer part of altitude        OUT_P_LSB = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, OUT_P_LSB_REG);        // Decimal part of altitude in bits 7-4        OUT_T_MSB = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, OUT_T_MSB_REG);        // Integer part of temperature        OUT_T_LSB = I2C_ReadRegister(MPL3115A2_I2C_ADDRESS, OUT_T_LSB_REG);        // Decimal part of temperature in bits 7-4                           /* Get altitude, the 20-bit measurement in meters is comprised of a signed integer component and        a fractional component. The signed 16-bit integer component is located in OUT_P_MSB and OUT_P_CSB.        The fraction component is located in bits 7-4 of OUT_P_LSB. Bits 3-0 of OUT_P_LSB are not used */                       Altitude = ( float ) (( short ) ((OUT_P_MSB << 😎 | OUT_P_CSB)) + ( float ) (OUT_P_LSB >> 4) * 0.0625;                     /* Get temperature, the 12-bit temperature measurement in °C is comprised of a signed integer component and        a fractional component. The signed 8-bit integer component is located in OUT_T_MSB. The fractional component        is located in bits 7-4 of OUT_T_LSB. Bits 3-0 of OUT_T_LSB are not used. */                           Temperature = ( float ) (( signed char ) OUT_T_MSB) + ( float ) (OUT_T_LSB >> 4) * 0.0625;                                                               }   The calculated values can be watched in the "Variables" window on the top right of the Debug perspective or in the FreeMASTER application. Attached you can find the complete source code written in the CW 10.3 as well as the FreeMASTER project.   If there are any questions regarding this simple application, please feel free to ask below. Your feedback or suggestions are also welcome.   Regards, Tomas Original Attachment has been moved to: FreeMASTER---XTRINSIC-SENSORS-EVK_MPL3115A2_BasicReadUsingInterrupt.zip Original Attachment has been moved to: XTRINSIC-SENSORS-EVK_MPL3115A2_BasicReadUsingInterrupt.zip
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Using this document you can simply introduce the measured data from the MPL3115A2 and you will get the expected output data for Altimeter/Barometric Pressure and Temperature measurements.
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