Payload electronics
Last updated
Last updated
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
Parts of the PCB schematics are presented bellow.
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
The assembly drawing for the PCB is shown bellow.
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
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
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
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
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
JP3 can be used to test GPIO pins in microcontroller.
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
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
TP2, TP3, TP4, TP5, TP6 are used to measure the outputs of the H1, H2, H3, H4 and H5 bridges respectively.
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
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.
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.
