HOST SFF Tier 2 Standards
The Tier 2 Small Form Factor (SFF) Family of Standards is a collection of the “SFF” standards that are in development. SFF means that the hardware components are designed to minimize the volume of the final enclosure.
These Tier 2 SFF architectures are driven by the need for standardized approaches for size, weight, and power (SWaP) constrained embedded computing solutions for a variety of DoD platforms.
The PC/104 Architecture Family (PC/104-AF) Core Technology Standard is the first of a series of Tier 2 SFF Standards that NAVAIR is developing.
The implementation of a Tier 2 SFF architecture consists of the following HOST components:
- HOST Enclosure – designed to suit the requirements of the target system
- HOST Module – Payload, Peripheral, Power Supply, and other standardized module types
- HOST External Interfaces – Connection of the signal and power interfaces between the HOST Transmission Components and the external system
Tier 2 SFF Standards ensure the proper development and interoperation of HOST-conformant COTS embedded modules.
(HOST PC/104-AF approach shown above)
HOST Tier 2 SFF PC/104-AF Overview
The HOST Tier 2 SFF PC/104-AF architecture is optimized for use in various types of embedded platforms due to several key attributes:
- Compact: 3.6 by 3.8 inches (90 x 96 mm) module size
- Self-Stacking: expands without backplane update
- Rugged: reliable in harsh environments
- Four corner mounting: resistant to shock and vibration
The Tier 2 PC/104-AF consists of three primary PC/104 architectural module types:
PCIe/104
PCIe/104 uses only the high-speed serial 156-pin PCI Express bus connector of PCI/104-Express. Standard features across all PCIe/104 module types include:
- Four x1 PCI Express Links
- Two USB 2.0
- ATX power and control signals
- Power: +3.3V, +5V, +12V
- SMBus
Additional high-speed bus capability is available through the use of PCIe x4, PCIe x16, USB 3.0, as well as SATA bus support, depending on the PCIe/104 module type. (Tier 2 defines both Type 1 and Type 2)
PCI/104-Express
PCI/104-Express consists of a 156-pin PCI-Express high-speed serial interconnect alongside the standard parallel 120-pin PCI bus connector, allowing it to support both the PCIe/104 bus functionality as well as the ability to bridge to the PCI/104 32-bit PCI bus architecture:
PCI/104
PCI/104 only utilizes the standard parallel 120-pin PCI bus connector, which supports a standard 33 MHz 32-bit PCI bus architecture:
