The document here explains the data and electrical interface between the ADCS and other subsystems, including Power, CDH and mechanical. The electrical and data interfaces of the ADCS subsystem are demonstrated below.
Figure 1 ADCS ICD block diagram
ADCS will have 4 ports(J1,J2,J3 and J4) which J3 will be connected to the CDH and PCU. J1 will be connected to the H-bridge for the 3rd magnetorquer. J3 and J4 will be connected to sun sensors.
Figure 2 shows that electric power is provided to ADCS from POW through a load distribution. The switch is controlled internally by the EPS controller and connects the ADCS_POWER_POS terminal to the Main Power bus (MPB) when closed. The ADCS should be supplied with 3.3V and 5V. Both supplies must be switched on simultaneously.
R-INT-0691: The ADCS subsystem shall not have a power consumption of more than 62.08 Wmin per orbit.
R-INT-0233: The ADCS subsystem shall use no more than 0.67 W.
ADCS_PWR_POS and ADCS_PWR_NEG are Power supply of ADCS board.
Figure 3 ADCS-POW ICD
MPB Voltage: 4.0 V to 7.3 V (Pending Change to actual range)
The data (communication) interface between ADCS and POW occurs through a 4-wire SPI connection. On the ADCS side, the SPI lines(Texas Instruments MSP430FR2476PT) connect directly to the ADCS module microcontroller .
MSP430FR2476 SPI Specifications
Operating voltage: 3.0 V
SPI type: 4-wire (MOSI, MISO, SCLK, CS)
SPI Clock frequency: up to 8 MHz
SOMI data setup time: 40 ns (master mode)
SIMO data valid time: 20 ns (master mode)
SIMO data setup time: 12 ns (slave mode)
SOMI data valid time: 42 ns (slave mode)
Voltage rating: -0.5 V to 4.6 V
Latching current limit: TBD
ON Resistance: 89 mohms
Turn on delay: < 315 microseconds
Turn off delay: < 15 microseconds
The ADCS attitude control processor receives commands from CDH before carrying out a task. All commands are framed with a bit before and after the identifying command value. The ADCS board only responds to proper command. It replies to a command with either an acknowledge (ACK) or a not acknowledge (NACK) response. In the case of a not acknowledge the CDH must send the command again.
Mounting holes
The dimensions of the stacked components and mounting locations are shown below. Maximum height: We have magnetorquers that extend the height to approximately 13 mm including connectors and mounts. The H bridges on the bottom of the board they would have a height as stated above of 1.905 +- 0.1 mm.
Mechanical
60 g mass/rod and core legth 5.2 cm
Electrical
- 3.3V and 5V supply
- Mag. Moment 0.2 Amp
- Power 0.2 W each
- Analog
Software
- Commanded by microcontroller
Thermal
- Operational Range: -80 to +80 degrees celsius
Surviving Temp: -80C to +80C
Mechanical
- 25 by 19 mm mask and 10 mm typical height
- Mass 30 gms in total
Electrical
- 3.3 V Supply voltage
- Input Leakage: -10 to +10 µA
Software
- Sends data to controller
- Uses SPI/USART Interface
Thermal
- Operating range: -40C to +125C
-Surviving Temp: -40C to +125C
Mechanical
- 3.0x3.0x0.9 mm
- Mounted with secondary locking features
- Low mass. 3-axis, chip style, surface mount
Electrical
- 2.16-3.6 V Supply Voltage
- Field Range +/-8 G - 1-2 Deg. heading accuracy
- Low power
Software
- SPI Interface
- Sends data to controller
Thermal
- Operating Range: -30C to +85C
- Surviving Temp. -40C to +125C
Mechanical
- 4.0x4.0x1.1 mm
- Mounted with secondary locking features
- Low mass. 3-axis, chip style, surface mount
Electrical
- 2.4-3.6 V Supply voltage
- +/- 245 dps full scale
- 8-bit temperature output
Software
- SPI Interface
- Sends data to the microcontroller
Thermal
- Operating range: -40C to +85C
-Surviving Temp: -40C to +85C
"SIGMA ACS Operations Manual", Sumin Alicia Hong, Patrick Irvin, York University