On Board Computer
The On Board Computer (OBC), developed jointly by CONAE and VENG, is a complex electronic unit, developed to manage satellite mission instruments, with data transfer rates up to 100 Mbps, in addition to providing general interfaces bi-level RS -422, analog channels for voltages and temperatures acquisition (internal and external housekeeping information) and capacity to command up to 24 heaters, through opto-coupled outputs.
It has a power module, a Single Board Computer module based on the UT699 LEON3-FT 32-bit processor and 6 additional functional modules, all linked through the cPCI 2.2 standard through the use of a Backplane. It also has an additional slot, designed to adapt to the needs of different missions/projects.
Mechanical and Operational Features
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|
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OBC WITHOUT REDUNDANCY(7 FUNCTIONAL MODULES) |
OBC WITH REDUNDANCY
COLD STANDBY(14 FUNCTIONAL MODULES) |
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DIMENSION |
21x27x27 [cm] |
39x27x27 [cm] |
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MASS |
7,5 [Kg] |
21 [Kg] |
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VOLTAGE |
21-36 [V] |
21-36 [V] |
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CONSUMPTION |
Rated consumption: 30[W]
Maximum consumption: 40[W] |
Rated consumption: 30[W]
Maximum consumption: 40[W] |
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OPERATION TEMPERATURE
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-10 °C to +40°C |
-10 °C to +40°C |
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LIFE TIME |
5 years |
5 years |
COMPONENTS—
Powerbox
Consists of 2 DC-DC converters that provide 4 regulated secondary voltages (+3.3, +5, +12 and -12V) that the equipment needs from an unregulated primary input supply (redundant or not) that it can vary between 21 and 36 V. It also implements configurable capabilities according to the needs of the specific application:
- Isolation of secondary-primary returns
- Limitation of the in-rush current
- Delay so that not all secondary voltages appear simultaneously
- Configuration as essential load (always powered regardless of which of the primary power lines is active) or not
INSTRUMENT ACQUISITION
Has the capacity to acquire data generated by up to 4 instruments simultaneously through dedicated LVDS interfaces. The total acquisition speed for the 4 channels simultaneously is up to 200 Mbps. CCSDS Packets “time-tagging” capability, with an uncertainty of less than 20 [μs]
In addition, this module has 3 Spacewire interfaces for transfer of acquired data at 100 Mbps. This transfer is carried out following the ECSS-E-ST-70-41-C (CCSDS Space Packet Protocol) standard.
COMMUNICATION
Has 1 MIL-STD-1553 Interface as a Remote Unit (designed for the exchange of telemetry and telecommand), with 1 MILSTD-1553 Interface as Bus Controller (designed to command other equipment or instruments) and 9 full-duplex UART/RS-422 serial interface ports.
GENERAL PURPOSEINPUT/OUTPUT
This module has 30 bi-level RS-422 input lines, 22 bi-level RS-422 output lines and 10 open-collector output lines.
SINGLE BOARD COMPUTER
Is the main module where processing, management and control activities are carried out. This module has the following blocks:
- UT699 LEON3-FT 32-bit processor
- RTEMS 4.10
- 2 redundant bootloader EEPROM memory banks
- 3 redundant banks of Program Flash Memory
- FGPA for the implementation of the interface via cPCI with the other 6 modules
- 3 Spacewire Interfaces
- 2 UART/RS-422 interfaces
- 2 RS-422 inputs for receiving synchronization pulses (PPS-in)
- 6 RS-422 outputs for synchronization pulse distribution (PPS-out)
- Watchdog provided by the capabilities of the UT699
TEMPERATURE ACQUISITION
Can acquire up to 96 temperature channels with a resolution of 12 bits grouped into 72 external and 24 internal temperature channels (3 channels for the OBC, 7 for calibration and 14 reserved for the expansion slot).
TEMPERATURE CONTROL
Has the capacity to command up to 24 action channels of 1[A] heaters. Each of these outputs is opto-coupled to maintain separation between the primary and secondary return.
