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SMR Evaluation Kit User Manual Experience and Reliability in Radar Technology- www.InnoSenT.de SMR Evaluation Kit user manual 1. Introduction Overview The Evaluation Kit “EVALKIT SMR-334” is a programmable compact radar system with a focus on creating a friendly and easy-to-use FMCW radar platform. It comes with a custom and open firmware that provides beginners with an easy way to experience radar sensors in their application and take a look into the signal processing with our detailed examples. The SMR-Eval Kit is built around the SMR sensor family and comes equipped with our flagship module SMR-334. The underlying STM32F401RE Nucleo Board from ST provides the necessary processing power and interface to the IDE and GUI. The Content kit comes with all necessary hardware, software and documentation to quickly start evaluating innovative radar technology. Introduction 3 Installation 4 Brief Introduction to Radar Principles 6 Features Getting Started 2 11 Radar configurable parameters 19 Data Transmission 20 Signal Processing 22 Frequency Auto-Calibration 22 Complete Application Diagram 24 Hardware 25 References 28 History 28 www.InnoSenT.de - Experience and Reliability in Radar Technology • Supports Doppler and FMCW radar principle • VCO controlled with 16-bit DAC on the SMR interface module • Stereo receiver • 12bit data acquisition • Configurable Doppler frequency and FMCW bandwidth • Frequency auto-calibration for compliance with government regulations • Simple GUI to visualize receive signals • ADC raw data and FFT display • Configurable radar parameters for advanced users - Bandwidth - ADC sampling rate - Frequency auto-calibration enable - Etc. • Full SMR antenna module control • System power and communication via a single USB interface • Source code with detailed comments giving users full control to the Evaluation Kit Experience and Reliability in Radar Technology - www.InnoSenT.de 3 SMR Evaluation Kit user manual 2. Installation In order to have a proper hardware installation, please follow the instructions below: • The SMR Evaluation Kit comes preassembled, however it is also possible to disassemble the two boards. • When the two boards are separated and need to be assembled, connect them as Hardware Installation in the following picture. Note: before connecting the two boards please make sure the power supply to the STM32F401RE board (via USB cable) is disconnected in order to The SMR-EvalKit packet consists of: prevent any damage to the system due to wrong connection and the connection should be checked again before applying the power supply. • SMR antenna module • Jumpers on the microcontroller board should be left unchanged. • STM32F401RE-Nucleoboard • Mini USB cable • Download link on the InnoSenT Homepage: Project files with Source code, GUI, User Manual, Quickstart Software, SMR Data Sheet) Figure 3: SMR-board and STM32 board connection Figure 1: SMR Antenna module Figure 2: STM32F401RE-Nucleoboard Software Installation Please refer to the SMR Evaluation Kit quick start guide for instructions about the software installation. 4 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 5 SMR Evaluation Kit user manual 3. Brief Introduction to Radar Principles As a summary the speed of an object can be evaluated by measuring the Doppler Doppler Principle frequency analysis with FFT), while considering the angle of the motion vector. Basis elements Please note: The CW-Doppler radar is the simplest kind of Radar, but most effective for detecting motion In the very rare case of a perfect circular motion of the object around the sensor, the and measuring speed. It utilizes the Doppler Effect, an effect which applies to all sorts of angle α would be 90o, which causes the cosine and therefore the Doppler frequency wave generators and says the following: to drop to zero. This specific motion won’t be detected by this type of radar. However frequency (in an analog system by counting the zero crossings or in digital system by this object would have to move along this circle with absolute perfection, which is Wave fronts, transmitted by a wave generator (sound, microwaves, light etc.) hit a moving highly unlikely for a real life object. target. Depending on the direction of the motion of this object, the wave fronts are either “compressed” or “stretched”, which finally results in a shift in frequency. The received signal is mixed with the unchanged transmit signal in the receiver (called “homodyne” mixing), which results in a sinusoidal intermediate frequency (IF). It doesn’t matter whether the sensor moves relatively to the object or the object moves relatively to the sensor. As a matter of fact, only the radial component of the velocity vector can be detected. The mathematical formula looks as follows: Identification of direction of motion Radar sensors with dual IF output can provide information about the direction of motion (leaving or approaching) simply by utilizing two mixer circuits, which are spaced by a quarter wavelength, called an I(n phase)/Q(uadrature phase) mixer. This information is useful for example in door opener applications, where the door should open only when a person approaches it. For detailed information on the radar basics, see Application_Note I-IV on the InnoSenT homepage. fD Doppler- or differential frequency f0 Transmit frequency of the radar v velocity of the moving object C0 Speed of light α Angle between the actual direction of motion and the connecting line Example The calculation of the parameters of the implemented CW-Doppler example is shown below: sensor-object Selecting 24GHz as transmit frequency, the following rule of thumb applies: speed of light C0 299792458 m/s CW-Frequency F depending on FREQ_START Hz Example: 24.000 sampling period With this simple equation the expected Doppler frequency can easily be calculated and the buffer length (number of samples) parameters of the IF-filter and amplifier can be defined. sampling time For instance it is not practical to design the upper frequency limit of the signal conditioning velocity resolution Ta N low pass filter (theoretical) to check the speed of cars for example on a German motorway, the amplifier needs to have low pass filter (current hardware) an upper frequency limit of at least 10 kHz corresponding to 220 km/h. high pass filter (theoretical) high pass filter (current hardware) 6 www.InnoSenT.de - Experience and Reliability in Radar Technology 0.0004 s 400 µs 128 Tsample 0.0512 s 51.2 ms 0.122 m/s 0.44 km/h LP 1250 Hz 915 Hz HP 19.53 Hz 20 Hz Vmin part of a unit detecting human beings much higher than 300Hz, since this corresponds to a speed of 6.8 km/h of a (pretty fast) pedestrian. On the other hand, when using radar sensors GHz Experience and Reliability in Radar Technology - www.InnoSenT.de 7 SMR Evaluation Kit user manual 4. FMCW Principle Basis elements The FMCW-(Frequency-Modulated-Continuous-Wave) radar is a common approach to detect stationary objects. Unlike a Pulse Radar the FMCW sensor emits a continuous wave changing the frequency linearly over time. Due to the propagation delay the received signal shows a slightly different frequency compared to the presently generated signal leading to a beat frequency in the receiver, which is proportional to the travelling time. The following equation describes the relation in case of a sawtooth-modulation: fD Δf T R C0 differential frequency frequency deviation (bandwidth) sawtooth prepetition time period distance of a reflecting object speed of light For the 24GHz-ISM-Band the modulation bandwidth is limited by regulation to 250MHz at maximum. In consequence the range resolution is limited to 60cm as a theoretical value. In practice ranging for distances greater than 2m is possible with simple data processing. Closer ranges are possible using more complex algorithms. For more detailed information on the radar basics, see Application_Note I-IV on the InnoSenT homepage. 8 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 9 SMR Evaluation Kit user manual Crosstalk 5. Getting Started A typical problem of FMCW radar is the crosstalk between transmitter and receiver Receive Signals Visualization due to non-ideal isolation between them. The crosstalk effect causes blind zone approximately 3m from sensor at 24GHz. This blind zone can be reduced by applying Highpass filtering, but it cannot be eliminated entirely. The SMR-EvalKit is a plug-and-play device. The system will boot the previously uploaded firmware as soon as it receives power via its USB port and the IF signals can be visualized using the SMR EvalKit GUI. To visualize receive signals: Example • open the SMR EvalKit GUI The calculation of the parameters of the implemented FMCW-modulation example is • select corresponding Comport of SMR EvalKit shown below: • Click Connect/Disconnect button to connect or disconnect to SMR EvalKit Comport speed of light C0 299792458 m/s bandwidth B depending on FREQ_ START and FREQ_STOP Hz Example: 250 sampling period Ta s 400 µs N 128 sampling time (modulation time) Tsample 0.0512 ms Rmin 0.60 m maximum range (theoretical) Rmax 37.8 m low pass filter (theoretical) LP 1250 Hz 915 Hz 19.53 Hz 20 Hz high pass filter (theoretical) HP high pass filter (current hardware) FREQ_START = 24.000GHz FREQ_STOP = 24.250GHz of raw receive signals and is displayed logarithmic (dB). Current modulation Comport Select Comport Connect/Disconnect s 51.2 range resolution low pass filter (current hardware) magnitudes are scaled in digit values. The bottom graph shows the corresponding FFT MHz 0.0004 puffer length (number of samples) In the GUI, the upper graph shows the raw receive signals on I- and Q-channel. The “Crosstalk effect” Object at FFT-bins 9-11 Note: When starting SMR-Evalkit, it may take a few seconds to perform initial frequency calibration and there is no data being transmitted to the PC during this time. It might take a few moments until a signal is displayed in the GUI. 10 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 11 SMR Evaluation Kit user manual Radar Setting Modification By modifying and uploading the source code onto the microcontroller board, the radar settings can be changed to different configurations. The following instructions show the procedure for doing this: a) Create a workspace folder for the project e.g: “C:\SMR_EvaluationKit_WS” b) Copy the SMR EvalKit firmware project folder into the workspace c) Run SW4STM32 software and select the created workspace folder b) d) Go to workbench a) Import the project containing the source code into the workspace. In the Project Expand the project and open the file “CONFIG.h” in “Inc” folder Explorer tab -> Right Click -> Import -> General -> Existing Projects into Workspace -> Select root directory -> Brower -> “select directory where the source code project located” -> OK -> Finish 12 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 13 SMR Evaluation Kit user manual c) The radar setting can be changed by modifying the parameters in this “CONFIG.h” e) Upload the modified source code onto microcontroller board. Right click on file. For example changing radar configuration to FMCW mode by setting project folder (or left click on debug arrow button) -> Debug As -> Ac6 STM32 C/C++ “#define MODULATION Application d) (1) ” Build the project after changing radar setting in “CONFIG.h” file. Note: It may be necessary to clean and refresh the project folder before building. Right click on project folder f) To run the application. Click on “Run” button. g) Once the firmware has even uploaded to the target and has been run it will be -> Clean Project. Right click on project folder -> Refresh. Right click on project folder -> Build Project. stored in the controllers flash memory and run even without connecting to the system workbench on power up. 14 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 15 SMR Evaluation Kit user manual SMR-EvalKit Pin layout and software components a) STM32Cubemx The SMR-EvalKit pin layout as well as software components configurations can be viewed using STM32Cubemx. To do this, open STM32Cubemx software and load the file “SMR_ EvalKit.ioc” in the SMR_EvalKit_Project folder. STM32F401RE Pin map (https://developer.mbed.org/platforms/ST-Nucleo-F401RE/) b) SMR-EvalKit Pin Configuration Name Pin map GPIO Description Note Vcc_EN PB10 Output Power supply of SMR board High-active SMR_Vcc_EN PB5 Output Power supply SMR radar module High-active SMR_Tx_out_EN PB4 Output Transmit signal amplifier High-active Vcc_div_EN PC7 Output Transmit signal down-conversion High-active Tx_Div_out PA0 Input Down-converted transmit signal Square wave signal Test_pin_0 PC8 Output For testing purpose high-active Test_pin_1 PC6 Output For testing purpose high-active RCC_OSC_IN PH0 n/a External clock input n/a RCC_OSC_OUT PH1 n/a External clock output n/a I_ADC PA4 Input Receive I-Channel signal Analog Q_ADC PA1 Input Receive Q-Channel signal Analog SPI1_CS PB6 Output SPI Chip select Low-active SPI1_CLK PA5 Output SPI Communication clock high-active SPI1_MOSI PA7 Output SPI Transmission of data to SMR board high-active SPI1_MISO PA6 Input SPI Reception of data from SMR board Unused USART2_TX PA2 Output Transmission of receive signal to PC High-active USART2_RX PA3 Input Reception commands from PC Unused TCK PA13 n/a Debug serial wire clock n/a TMS PA14 n/a Debug serial wire I/O n/a SWO PB3 n/a Debug serial wire output trace port n/a SMR-EvalKit pin configuration with respect to STM32F401RE microcontroller board 16 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 17 SMR Evaluation Kit user manual Note: when toggling the following SMR I/O-pins: Vcc_EN, SMR_Vcc_EN, SMR_Tx_EN, Vcc_Div_ EN, it is absolutely important to follow the scheme below with a 1ms delay between each pin. Switching on: Vcc_EN -> SMR_Vcc_EN -> SMR_Tx_EN and Vcc_div_EN Switching off: SMR_Tx_EN and Vcc_Div_EN -> SMR_Vcc_EN -> Vcc_EN c) Software components brief description Component 6. Radar configurable parameters The “CONFIG.h” file in the source code provides a list of configurable parameters. Usage HSE • High speed external clock for clocking MCU system Timer_2 • Measure SMR down-converted transmit signal frequency Timer_4 • Control ADC sampling period • Generate FMCW ramp • Monitor measurement cycle duration Timer_5 • Monitor communication message timeout via USART SPI • Set SMR transmit frequency ADC • Sample analog receive signals of SMR module DMA • Read sampled signals from ADC registers • Write data to SPI registers USART • Communicate to PC GPIO • Interface between SMR board and MCU board Parameter Description Note Unit MODULATION selecting of radar principle 0: Doppler principle 1: FMCW principle - FREQ_START*) Start frequency in FMCW mode Min: 24000 Max: 24250 MHz FREQ_STOP Stop frequency in FMCW mode Min: 24000 Max: 24250 MHz FREQ_CALIB_EN Frequency calibration enable SAMPLE_PERIOD ADC sampling interval 1*) µs CYCLE_DURATION Measurement cycle duration 2*) µs FREQ_CALIB_INTVL Frequency auto-calibration interval BAUDRATE Data transmission rate 0: Off 1: On Number of cycles Default: 115000 Bits/s *): FREQ_START must always be smaller than FREQ_STOP: FREQ_START < FREQ_STOP 1*): A careful consideration should be taken when changing the parameter “SAMPLE_ PERIOD” since an improper value of this parameter may cause application software not functioning correctly. 2*): Min. CYCLE_DURATION = SAMPLE_PERIOD*FFT_SIZE + FRAME_LENGTH*10/BAUDRATE E.g.: SAMPLE_PERIOD = 400µs, FFT_SIZE = 128, FRAME_LENGTH = 1031 bytes, BAUDRATE = 115000bits/s -> Min. CYCLE_DURATION = 400µs*128 + 1031*10/115200 ≈ 141ms 18 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 19 SMR Evaluation Kit user manual 7. Data Transmission Transmission State During the time when data is being transmitted to the PC, “LED2” on the microcontroller board will turn on and it will turn off again when the transmission is completed. During At the end of each measurement, the raw data as well as its FFT magnitudes in normal operation the LED will flash due to the continuous data transmission. logarithmic scale will be transmitted to the GUI. The data is transmitted in a frame with the following structure: Example: FFT_SIZE = 128 (i.e. 128 samples) Byte No. Byte 1 Byte 2 Byte 3 Byte 4,5 Byte 6,7 Byte 260,261 260,261 Byte 262,263 Byte 516,517 Byte 518,519 520,521 Byte 1026,1027 1028,1029 Byte 1030 Byte 1031 Data type uint8 uint8 uint8 uint16 int16 int16 int16 int16 int32 int32 1 byte 1 byte Modulation Number sample Raw I1 Raw I128 Raw Q1 Raw Q128 FFT-mag 1 FFT-mag 128 CS ED Content SD FC SD: start delimiter = 162 (0xA1) uint8 FC: function code = 224 (0xE0) uint8 Modulation: 0-Doppler, 1-FMCW uint8 Number sample: number of captured samples for single measurement uint16 Raw I1: sample 1st of raw I signal int16 Raw I128: sample 128th of raw I signal int16 Raw Q1: sample 1st of raw Q signal int16 Raw Q128: sample 128th of raw Q signal int16 FFT-mag 1: magnitude of FFT sample 1st in logarithmic scale int32 FFT-mag 128: magnitude of FFT sample 128th in logarithmic scale int32 CS: checksum = (sum of Byte2 to Byte1029) & 0x000000FF uint8 ED: end delimiter = 22 (0x16) uint8 Note: Depending on FFT_SIZE the frame length will change and byte numbers may need to be adjusted, however the frame’s structure remains. 20 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 21 SMR Evaluation Kit user manual Signal Processing Transmit frequency measurement The SMR-module outputs a square wave prescaler signal with a frequency This is an illustration of the signal processing for both Doppler and FMCW mode. corresponding to 1:8192 of its current transmit frequency. The prescaler is enabled by connecting “Vcc_div_EN” to 3.3V. Example: A transmit frequency of 24.125GHz will result in a square wave signal with a frequency of approx. 2.944946MHz. 8. Frequency Auto-Calibration This square wave signal is routed into the microcontroller board via the “TX_Div_out” One highlighted feature of the SMR-Evalkit is the ability to minimize transmit frequency channel of the microcontroller is applied on the “TX_Div_out” pin to detect and count drift over temperature. The following diagram describes the principle behind the the number of rising edges of the square wave signal in a duration of 100ms. After the frequency calibration. sampling process, the frequency of the square wave signal is calculated by dividing the pin. In order to measure the frequency of the square wave signal, an input-capture number of detected rising edges by 100ms. Example: 293584 rising edges detected -> 2.93584MHz square wave signal b) Frequency shift calculation After measuring the frequency of the square wave signal, the difference between the target frequency and the measured frequency is calculated and used for correcting the transmit frequency. c) Transmit frequency correction The calculated frequency difference is compared with a frequency tolerance. When the difference exceeds the tolerance, an adjustment for transmit frequency with a pre-defined value is performed to move the transmit frequency closer to desired frequency. This frequency auto-calibration routine is repeated after a defined duration and this defined duration can be configured by the users. After calibration process, the application will wait for one measurement cycle before continuing with measurements. a) In the first step the transmit frequency of SMR module is measured. Afterwards the difference between the target transmit frequency and the measured transmit frequency is calculated. Based on this difference the transmit frequency is Note: In Doppler mode only start frequency is calibrated. In FMCW mode, start- and stop-frequency are calibrated alternately.   changed accordingly and tested again. 22 www.InnoSenT.de - Experience and Reliability in Radar Technology Experience and Reliability in Radar Technology - www.InnoSenT.de 23 D C B A 4 SPI_MOSI 1 GND TX_ON VCC_SMR Enable_VCC 8 IT4397 Stiftleiste 7 6 5 4 3 2 X3 1 CN9 8 IT4397 Stiftleiste 7 6 SPI_CLK 5 GND VCC_DIV +5V 3 SPI_CS 2 X2 1 CN5 8 IT4397 Stiftleiste 7 6 5 4 3 2 X1 1 CN6 2 GND C18 AT0083 1µ IT0073 0R R6 R9 AT0026 100R GND R5 AT0026 100R DAC (V-Tune) GND C2 AT0077 100n 2 R10 AT0026 100R R11 AT0026 100R GND GND IC2 AT0171 AD5662WARMZ GND GND 3 AT0117 4k7 R22 IT0561 10k R23 IT4027 SMR-334 Gnd TXOn Vcc Q VccPtat I Vtune DivOut Gnd VccDiv IC3 6 7 8 9 10 1 5 4 3 2 1 R15 IT0561 10k GND C8 AT0077 100n GND IT0073 0R R8 R16 AT0117 4k7 GND R12 IT0561 T2 10k IT0343 BCW60C 3 2 GND D2 IT4000 LED grün C21 AT0077 100n C19 AT0077 100n GND AT0026 100R R7 GND AT0077 100n GND GND AT0117 4k7 R13 R14 IT0730 390R 1 T1 AT0046 FDV304P GND C7 AT0078 10µ GND AT0083 1µ C5 C6 AT0078 10µ GND IT3629 ADM7154ACPZ-3.3-R7 AT0078 10µ C17 3 Voltage-regulation IC1 5 4 Ref_Sens GND 6 3 Ref Byp 7 2 En Out 8 1 In Vreg C16 C3 AT0075 100p AT0083 1µ C4 IT4000 LED grün GND GND C1 AT0078 10µ GND R25 AT0117 4k7 1 2 3 IT0564 1k 3 1 VCC_SMR 2 C20 AT0077 100n GND GND D4 IT4000 LED grün R24 IT0730 390R T5 IT0343 BCW60C 4 AT0117 4k7 R18 4 D3 IT4000 LED grün R19 IT0730 390R 1 T3 AT0046 FDV304P C9 AT0075 100p GND 3 2 2 1 2 1 2 R26 4 VOUT 5 SYNC 6 VFB SCLK 1 VDD VREF DIN 7 GND 8 +3V3 R21 AT0117 4k7 GND R17 IT0561 T4 10k IT0343 BCW60C 3 2 1 VCC_DIV D1 3 2 1 2 +3V3 AT0078 10µ C30 Signal_I Signal_Q AT0078 10µ C22 R20 IT0561 10k GND 5 IT1196 1k2 R32 IT1196 1k2 R27 C10 AT0077 100n 5 GND V4 8 V+ C31 n.b. 0402 5 6 3 2 Out 1 Out 7 IT3310 ADA4841-2YRMZ + - IC4C IT0563 15k IT2689 5n6 R33 C32 GND V4 8 V+ 6 R29 R34 6 IT1196 AT0078 1k2 10µ C33 IT1196 AT0078 1k2 10µ C25 C26 n.b. 0402 IC5A IT3310 ADA4841-2YRMZ Signal-ampifier GND C11 AT0077 100n IT3310 ADA4841-2YRMZ + - IC4B IT0563 15k IT2689 5n6 R28 C24 IC4A IT3310 ADA4841-2YRMZ C23 n.b. 0402 Vmid1 www.InnoSenT.de - Experience and Reliability in Radar Technology Vmid1 24 5 6 3 2 1 Out 7 Name Zirk IT3310 ADA4841-2YRMZ + - IC5C IT1201 3k3 IT2779 27n R35 C35 IT3310 ADA4841-2YRMZ + - Out IT1201 3k3 7 7 GND 8 1 2 3 4 5 Cannot open file C:\Users\Public\Doc uments\Altium\AD\ Templates\Logo 8 InnoSenT cmyk.png IT4405 Stiftleiste 6 X4 TP4 V-tune TP2 Q-Signal CN8 Vmid2 C15 AT0078 10µ GND R4 IT0561 10k R3 IT0561 10k GND TP1 Div-out C37 n.b. 0603 GND TP3 I-Signal C36 AT0083 1µ GND C29 n.b. 0603 GND GND C28 AT0083 1µ Vmid1 C14 AT0077 100n Eval-SMR_1.PrjPcb Titel Dokument Eval-SMR_1.SchDoc Seite 1 von 1 IT0164 100k R39 IT0073 0R R40 AT0094 100R R36 AT0094 100R R31 C13 AT0078 10µ GND R2 IT0561 10k R1 IT0561 10k GND IT2779 27n R30 C27 IC5B GND C12 AT0077 100n Datum erstellt 20.03.2017 geprüft C34 n.b. 0402 Vmid2 D C B A 9. Complete Application Diagram Vmid2 1 SMR Evaluation Kit user manual 10. Hardware Schematic circuit Experience and Reliability in Radar Technology - www.InnoSenT.de 25 SMR Evaluation Kit user manual Layout TOP 26 www.InnoSenT.de - Experience and Reliability in Radar Technology BOTTOM Experience and Reliability in Radar Technology - www.InnoSenT.de 27 SMR Technical characteristics See Data Sheet SMR-334 11. References STM32F401RE Nucleo reference manual: http://www.st.com/content/ccc/resource/technical/document/reference_manual/5d/b1/ ef/b2/a1/66/40/80/DM00096844.pdf/files/DM00096844.pdf/jcr:content/translations/ en.DM00096844.pdf STM32F401xE datasheet: http://www.st.com/content/ccc/resource/technical/document/ datasheet/30/91/86/2d/db/94/4a/d6/DM00102166.pdf/files/DM00102166.pdf/jcr:content/ translations/en.DM00102166.pdf STM32 Nucleo-64 board user manual: http://www.st.com/content/ccc/resource/technical/document/user_manual/98/2e/ fa/4b/e0/82/43/b7/DM00105823.pdf/files/DM00105823.pdf/jcr:content/translations/ en.DM00105823.pdf 12. History Document revision 28 Date Change log Author 1 01.03.2017 first release BL 1.1 20.03.2017 Added description “Transmission State” SG 1.2 26.07.2017 Release CD 1.3 22.05.2018 Corrected USART2_TX/RX pins BL InnoSenT GmbH Tel.: +49-9528-9518-0 Am Roedertor 30 Fax.: +49-9528-9518-99 97499 Donnersdorf E-mail: info@innosent.de Germany www.innosent.de www.InnoSenT.de - Experience and Reliability in Radar Technology