Payload electronics
The PCB ensures proper functioning of the F.R.W., the z-axis magnetorquer and the sensors: the magnetometer, the gyroscope and the temperature sensors. It also provides the electrical interface for power delivery and communication with the SR-NANO-BUS platform. The PCB is mechanically compatible with other parts of the satellite and was designed to work properly in space conditions (especially low and high temperatures). More information about payload electronics system can be found in: Artur Hadasz, "Project of the payload computer and the electronic circuit of the controller for the Kraksat satellite angular velocity control", Master Thesis, AGH University of Science and Technology, Cracow 2019, supervisor: Paweł Zagórski
Schematics
Parts of the PCB schematics are presented bellow.
Bill of materials
The bill of materials for the PCB is shown in the table bellow.
Designator | Manufacturer | Manufacturer part number |
H1, H2, H3, H4, H5 | ALLEGRO MICROSYSTEMS | A4950ELJTR-T |
C1, C8, C17, C19 | MURATA | GRM31CR6YA106KA12L |
C2, C3, C5, C6, C7, C9, C10, C11, C13, C14, C15, C16, C18, C20, C21, C22, C23 | TDK | CGA3E3X8R1H104K080AB |
C4 | AVX | 06031C103JAT2A |
C12, C24, C25, C26, C27 | KEMET | C2220X106K5RACTU |
R1, R3, R7, R10 | VISHAY | CRCW06034K70FKEA |
R2, R4, R5, R11, R12, R15, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, R29 | VISHAY | CRCW06030000Z0EA |
R6, R17 | VISHAY | CRCW060310K0FKEA |
R9, R16 | WALSIN | WR06X47R0FTL |
R13 | VISHAY | CRCW060315K0FKEA |
R14 | VISHAY | CRCW060347K0FKEA |
Y1 | ABRACON | ASTMHTA-25.000MHZ-ZJ-E |
L1 | MURATA | LQM21FN100M80L |
U1 | STMICROELECTRONICS | LSM9DS1TR |
U2 | STMICROELECTRONICS | STM32L476RCT6 |
T1, T2, T3 | LITTELFUSE | SMF3.3 |
T4 | STMICROELECTRONICS | SMBJ16A-TR |
J1, J2, J3, J4, J5, J6, JP1, JP2, JP3, JP4, LED1, LED2, R8, S1, TP1, TP7, TP8, TP9 | DO NOT PLACE |
Assembly drawing
The assembly drawing for the PCB is shown bellow.
Functions of microcontroller pins
The table below provides information about microcontroller pins - the peripherals they are used by (their function in that peripheral) and their function in the KRAKsat mission. In cases where it is required, more detailed description is presented in the subsections below.
Pin | Peripheral | Function |
PA13 | JTMS-SWDIO | Programming with ST-Link |
PA14 | JTCK-SWCLK | Programming with ST-Link |
PB3 | JTDOTRACESWO | Programming with ST-Link |
PA2 | USART2_TX | UART TX port for test communication using ST-link |
PA3 | USART2_RX | UART RX port for test communication using ST-link |
PC6 | TIM3_CH1 | PWM passed to the H-bridge controlling phase 1 of the FRW in direction 1 |
PC7 | TIM3_CH2 | PWM passed to the H-bridge controlling phase 1 of the FRW in direction 2 |
PC8 | TIM3_CH3 | PWM passed to the H-bridge controlling phase 2 of the FRW in direction 1 |
PC9 | TIM3_CH4 | PWM passed to the H-bridge controlling phase 2 of the FRW in direction 2 |
PA8 | TIM1_CH1 | PWM passed to the H-bridge controlling phase 3 of the FRW in direction 1 |
PA9 | TIM1_CH2 | PWM passed to the H-bridge controlling phase 3 of the FRW in direction 2 |
PA10 | TIM1_CH3 | PWM passed to the H-bridge controlling phase 4 of the FRW in direction 1 |
PA11 | TIM1_CH4 | PWM passed to the H-bridge controlling phase 4 of the FRW in direction 2 |
PB6 | TIM4_CH1 | PWM passed to the H-bridge controlling the ADCS coil in direction 1 |
PB7 | TIM4_CH2 | PWM passed to the H-bridge controlling the ADCS coil in direction 2 |
PC0 | I2C3_SCL | SCL signal for communication with IMU using I2C |
PC1 | I2C3_SDA | SDA signal for communication with IMU using I2C |
PB10 | USART3_TX | UART TX port for communication with ther arbiter |
PB11 | USART3_RX | UART RX port for communication with ther arbiter |
PB0 | ADC12_IN15 | 12 V power level measuring |
PB2 | COMP1_INP | The comparator measuring power level and generating interrupts |
PB12 | GPIO | User GPIO output |
PA5 | SPI1_SCK | SC in thermometer |
PA6 | SPI1_MISO | MISO for SPI communication with thermometer, SI/O in thermometer |
PA7 | SPI1_MOSI | MOSI for SPI communication with thermometer, SI/O in thermometer |
PC4 | GPIO | /CS in thermometer |
PC10 | GPIO | User GPIO |
PC11 | GPIO | User GPIO |
Connectors and test points
Connector J1
J1 is electronic interface between payload and OBC. It provides 3.3V and 12V supply voltage and UART serial communication.
Pin number | Function |
1 | UART TX on payload side |
2 | NRST |
3 | 3.3V |
4 | 3.3V |
5 | 12V |
6 | 12V |
7 | UART RX on payload side |
8 | Not connected |
9 | GND 3.3V |
10 | GND 3.3V |
11 | GND 12V |
12 | GND 12V |
Connector J6
J6 connects the PCB to the ADCS Z-coil and the thermometer.
Pin number | Function |
1 | ADCS coil terminal 1 |
2 | ADCS coil terminal 2 |
3 | /CS in thermometer |
4 | VDD |
5 | SI/O in thermometer |
6 | GND |
7 | SC in thermometer |
8 | GND |
Connector JP1
JP1 allows to check if the IMU works correctly using an external microcontroller. It also enables connecting the Sparkfun 9DOF Sensor Stick to the board if the IMU found on the PCB stops working.
Pin number | Function |
1 | GND |
2 | VDD |
3 | SDA |
4 | SCL |
Connector JP2
JP2 can be used as ports of UART com 2 used to verify the correctness of implemented features.
Pin number | Function |
1 | UART TX |
2 | UART RX |
Connector JP3
JP3 can be used to test GPIO pins in microcontroller.
Connector JP4
JP4 is used to program the microcontroller via ST-Link.
Pin number | Function |
1 | Target VDD |
2 | TCK |
3 | GND |
4 | TMS |
5 | NRST |
6 | SWO |
Test point TP1
The signals which can be measured on terminals of the TP1 test point are described in table below.
Pin number | Function |
1 | PWM passed to the H-bridge controlling the ADCS coil, terminal 1 |
2 | PWM passed to the H-bridge controlling the ADCS coil, terminal 2 |
3 | SC in thermometer |
4 | SI/O in thermometer |
5 | /CS in thermometer |
6 | GND |
7 | PWM passed to the H-bridge controlling the flywheel coil 4, terminal 1 |
8 | PWM passed to the H-bridge controlling the flywheel coil 4, terminal 2 |
9 | PWM passed to the H-bridge controlling the flywheel coil 3, terminal 1 |
10 | PWM passed to the H-bridge controlling the flywheel coil 3, terminal 2 |
11 | PWM passed to the H-bridge controlling the flywheel coil 2, terminal 1 |
12 | PWM passed to the H-bridge controlling the flywheel coil 2, terminal 2 |
13 | PWM passed to the H-bridge controlling the flywheel coil 1, terminal 1 |
14 | PWM passed to the H-bridge controlling the flywheel coil 1, terminal 2 |
Test points TP2, TP3, TP4, TP5, TP6
TP2, TP3, TP4, TP5, TP6 are used to measure the outputs of the H1, H2, H3, H4 and H5 bridges respectively.
Test points TP7 and TP8
TP7 and TP8 are used to check the power supply. The table below shows the signals on each testpoint terminal.
Test point | Terminal number | Signal |
TP 7 | 1 | GND |
TP 7 | 2 | 12V |
TP 8 | 3 | GND |
TP 8 | 4 | 3.3V |
Sensors
IMU
The LSM9DS1 is a sensor featuring a 3D digital linear acceleration sensor, a 3D digital angular rate sensor, and a 3D digital magnetic sensor. The LSM9DS1 has a linear acceleration full scale of ±2g/ ± 4g/ ± 8/ ± 16g, a magnetic field full scale of ±4/ ± 8/ ± 12/ ± 16 gauss and an angular rate of ±245/ ± 500/ ± 2000 dps. The LSM9DS1 includes an I2C serial bus interface. It is guaranteed to operate over an extended temperature range from -40°C to +85°C.
Thermometer
The LM74 is a temperature sensor with analog-to-digital converter with an SPI interface. The host can query the LM74 at any time to read temperature. A shutdown mode decreases power consumption to less than 10 μA. This mode is useful in systems where low average power consumption is critical.The LM74 has 12-bit plus sign temperature resolution (0.0625 °C per LSB) while operating over a temperature range of -55°C to +150°C.
Last updated
