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Introduction
Introduction
This page outlines the Mechanical, Electrical and Thermal interface of the CDH Subsystem.
For the information about data interfaces and software please see Flight Software page
CDH Module Layout
CDH Module Layout
The components of CDH will be mounted onto a PCB that will mount to the inside of the COMMS/CDH module via four mechanical fasteners located at the four vertices of the PCB as shown below.
Mechanical Interface
Mechanical Interface
Position: Will be mounted on the CDH Module of the spacecraft
Mass: 53.8 g (< 96g)
Volume/Dimensions: 90mm x 90mm x 1.57mm (< R-CDH-0165 - 0167)
Outgassing: All hardware components compliant and will be conformally coated
Electrical Interface
Electrical Interface
1 load switch (MOSFET) power input at unregulated battery voltage (Vbat = 6.4 +/- 0.4 V)
1 CAN Bus connection line
1 SPI connection for ADCS
1 analog connections for thermistor
CDH External Interfaces
CDH External Interfaces
The external interface of the CDH module includes connection to the POW subsystem for input power the CDH module and connection to the COMS, PLD and ADCS subsystems for data transmission between the subsystems as summarized in the schematics below. Thermal subsystem uses indirect connections to CDH through other subsystems.
The COMS and PLD subsystems are connected via CAN Bus while the ADCS subsystem is connected via a SPI connection to allow transmission of data between the subsystems. The power and data (CAN and SPI) harnessing of the CDH module is detailed below.
Wires A, B, C are soldered to the CDH module at the stated solder location on the CDH board on the -Z of the CDH board. The free-ends of wires A and B are soldered to the male connector 6b at the corresponding pin number and free-end of wire C are soldered to male connect at 3b at the corresponding pin number (see Harness ICD for details).
CDH Umbilical Design
CDH Umbilical Design
The umbilical connector will be implemented in the Flight Model of CDH. The umbilical connector will include 4 JTAG signals from the CDH to allow for re-programing and debugging of the CDH PCB during Phase D testing. The 4 signals will be routed via inter-modular connector 6b carrying signals UMB_CDH_1, UMB_CDH_2, UMB_CDH_3, UMB_CDH_4.
See Harness ICD Electrical Interface for connector details.
Thermal Interface
Thermal Interface
Thermal subsystem uses indirect connections to CDH through other subsystems.
Operational temperature range: -40°C to 85°C.
Survival temperature range: -40°C to 85°C.
1 thermistor to measure CDH processor temperature
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