Table of Contents
This section covers the FPGA board, CoaXpress Mezzanine board, and enclosure in detail. This is the final stage of MSD I, where the detailed features of the sub-system design begin to appear. Ideally, this should be the finalizing step to completing the design and moving forward with physical implementation. For the Ruggedized Camera Encoder project, the deliverables are as follows:
- System Block Diagrams
- Board Block Diagrams
- HSMC Part Placement
- HSMC Schematic
- HSMC BOM
- FPGA Board PArts Placed
- All Major Data Busses Connected (Preliminary Schematic)
- Initial FPGA Board BOM
- FPGA and HSMC Parts Databased
- Detailed CAD
- Test Plan
- CAD Models
- CAD Drawings
- Thermal Simulations
- Mechanical BOM
- IP67 Compliance Description
This page is split into three parts. Two electrical and one mechanical. The two electrical sections are the FPGA Board and the HSMC Board. The mechanical section covers the enclosure in detail.
The FPGA board takes most of it's design features from mixing the Altera Cyclone V Development kit and combining it with the robust D3 design core design. The Altera Cyclone development kit has many of the I/O capabilities that the FPGA board will have, so it can be completed in a way similar to the dev kit.
The power calculations were assessed by incorperating the power of the FPGA, the HSMC Board and the I/O to give a grand total. This is shown in the initial power calculations.
Bill of Materials
The BOM was completed using as many of the already well established D3 parts as possible. Once the BOM was generated, the parts were then added to the initial schematics for the design.
Schematics & Flow Charts
The schematics are in progress, and are being worked on by Kyle Jason and Jordan O'Connor. These schematics can be seen in three sections: the power, the FPGA and the I/O. These are not completed designs (as of 5/26/14) but will be completed in the following weeks as D3 criticizes and tweaks the designs.
Engineering AnalysisThis section is devoted to a thorough analysis of the system that is proposed for the CoaXPress interface layer. This interfacing happens at two levels--one at the software level and at the hardware level.
Schematics & Block DiagramsThis section contains the schematics produced for the CXP HSMC board as well as the block diagrams, which provide details concerning the functionality of the subsystem. For information concerning the technical details of the functionality of the subsystem, see the design documentation.
Bill of MaterialsThis section provides the bill of materials that corresponds to the CoaXPress HSMC subsystem.
Test PlanThis section contains the document summarizing the test plan and the technical details and implications therof.
Test PlanTesting will see revision as MSD II proceeds.
- Exploded View with Bill of Materials (5/26/2014)
- Enclosure (5/26/2014)
- Drive Bracket A (5/26/2014)
- Drive Bracket B (5/26/2014)
- Board Tray (5/26/2014)
- Board Tray Top (5/26/2014)
- Front Door (5/26/2014)
- Back Door (5/26/2014)
- Door for SSDs (5/26/2014)
One of the biggest challenges faced with the design of the enclosure is how to dissipate the heat generated within the enclosure. The inclusion of the HSMC card, DesignCore board, the FPGA board being designed and the hard drives easily made heat dissipation a major concern especially with an enclosure design to be fully sealed and meet the IP67 requirement.
Case 1 consists of setting the outside of the enclosure to room temperature or 20 degrees Celsius. Based on initial estimates each chip on the top and bottom board produce 9 watts of energy and 1 watt on each surface of the hard drive tray. This energy was divided by the surface area on which it is produced in order to obtain a heat flux. As we can see from the image, we see a change in temperature of about 20 degrees. The bottom chip dissipates heat a ot better due to the higher surface area of the board tray.
Case 2 consists of the extreme scenario of the enclosure being exposed to a temperature of 60 degrees Celsius. As within case 1, the chips and hard drives produce the same amount of energy. Once again, we get a change of temperature of about 20 degrees with the top chip being the hottest portion. Despite the higher temperature, the enclosure reaches a high of about 79 degrees Celsius with the electrical equipment being rated for 85 degrees celsius which provides some leeway with the energy that can be produced within the enclosure.
It should be noted that these numbers at this point are only an estimate of the heat to be produced. Once the layout of the boards is near complete a better idea of placement of components and the amount of energy they produce will help in refining the enclosure design. This will be an iterative process until a sufficient design to dissipate heat is finalized.
Mechanical Bill of Materials
Below is a photo of the intial bill of materials for the mechanical components of the enclosure. for the document itself please refer to the excel spreadsheet link.
IP67 Compliance DescriptionIngress Protection (IP) Ratings is a method to quantify terms such as “waterproof” or “dustight”. Established by the International Electro Technical Commission in order to set a standard of ratings for a piece of electrical equipment or an enclosure housing electrical equipment. IP Ratings consist of IP followed by two numbers (IPXX) specifying a degree of protection. The first number specifies protection against the ingress of solid objects and the second number specifies protection against the ingress of liquids. The following table breaks down the IP Ratings and the extent of protection they cover.
|IP||First Digit (Ingress of Solid Objects)||Second Digit (Ingress of Liquids)|
|0||No protection||No protection|
|1||Protected against solid objects over 50mm e.g. hands, large tools.||Protected against vertically falling drops of water or condensation|
|2||Protected against solid objects over 12.5mm e.g. hands, large tools.||Protected against falling drops of water, if the case is disposed up to 15 from vertical.|
|3||Protected against solid objects over 2.5mm e.g. wire, small tools.||Protected against sprays of water from any direction, even if the case is disposed up to 60 from vertical.|
|4||Protected against solid objects over 1.0mm e.g. wires.||Protected against splash water from any direction.|
|5||Limited protection against dust ingress. (no harmful deposit)||Protected against low pressure water jets from any direction. Limited ingress permitted.|
|6||Totally protected against dust ingress.||Protected against high pressure water jets from any direction. Limited ingress permitted.|
|7||N/A||Protected against short periods of immersion in water.|
|8||N/A||Protected against long, durable periods of immersion in water.|
|9K||N/A||Protected against close-range high pressure, high temperature spray downs.|
At this point it should be noted, the digit indicating the rating of the ingress of solid objects only goes up to 6 which is the reason why it is not applicable beyond this point. In order to meet the requirement of making the enclosure IP67 a series of rugged connectors had to be chosen in order to meet this standard. The datasheets/drawings of the individual connectors chosen can found below.
- (34-1030) BNC Connector
- (RJFTV2PE1N) RJ45 Connector
- (EQW.LM.U2A.XPL) USB Connector
- (ACRK1203GSCM1) Power Connector
In addition to the rugged connectors, the end plates, SSD tray door and any screws used will be sealed using an O-ring in order ensure there will be no ingress of water.