Bus is now compatible with the full size PCIe/104 connector

The history of the stackable PC/104 architecture is tightly coupled to the concept of building on the foundation of the PC market as defined by the major processor and peripheral chip manufacturers. This began with the ISA bus (PC/104), then the ISA and PCI buses (PC/104-Plus), then the PCI bus (PCI/104), and finally the PCI and PCIe buses together (PCI/104-Express). For additional room on a module, the PCIe/104 format removes the PCI bus. This roadmap allows maximum use and leveraging of the vast resources and economies of scale of the PC community in both hardware and software development. The format also allows maximum backward compatibility with minimal stacking overhead, if any, and allows future bus advancements as technologies develop and mature.

The origin of the OneBank option to the stackable PCIe/104 bus comes from the desire to minimise the resources needed for a given application. The standard PCIe/104 bus allows for maximum bus feature flexibility. The device consists of a three bank connector with 152 pins and is available as either a Type 1 or Type 2. Both Type 1 and Type 2 have a common feature set and pin assignments which include: four x1 PCIe links, two USB 2.0, ATX power and control signals: +5V standby, power supply on, power good, power: +3.3V, +5V, +12V and SMBus. Type 1 has the common feature set plus one x16 PCIe link that can be configured as two x8 links or two x4 PCIe links dependent on the host. Type 2 has the common feature set plus two x4 PCIe links, two USB 3.0, two SATA, LPC bus and RTC Battery. With speed capability up to PCIe Gen 3, developers are given plenty of bandwidth for the future.

The OneBank connector concept consists of removing two of the three ‘banks’ of the standard PCIe/104 connector, resulting in a 52-pin connector as opposed to the full-size 156-pin connector. The OneBank connector is positioned so that it will plug into the bank 1 of the standard PCIe/104 connector. Thus, the signals of the OneBank include the same four x1 PCIe links, two USB 2.0, ATX power and control signals: +5V standby, power supply on, power good, power: +3.3V, +5V (reduced current) as found on the first bank of the standard PCIe/104 bus, making them plug in compatible. This preserves the stackability and compatibility of PCI/104-Express and PCIe/104 modules along with the new OneBank modules. By removing two of the banks, 0.513 in2 of PCB real estate on each side is freed up. And with speed scales up to PCIe Gen 3 on the PCIe/104 bus, developers are given plenty of bandwidth for the future even with just four x1 PCIe links.

As with all of the stackable buses adopted by the PC/104 Consortium, the PCIe/104 OneBank connector can be immediately incorporated across the Consortium's 104, EPIC and EBX form factors. In addition it can be utilised on other form factors not housed by the Consortium to provide convenient, cost-effective mezzanine I/O expansion.
Longevity is one of the hallmarks of the PC/104 Consortium’s technology. Many customers require the stable, long-term supply that PC/104 module vendors offer. PC/104’s reliability is valued by thousands of OEMs in application areas such as industrial control and instrumentation, military and aerospace, and medical. The compatibility of OneBank with existing PCIe/104 products helps to preserve customers’ investments in product designs while opening additional opportunities for cost savings, high levels of integration, and system expandability.

"The OneBank connector does a nice job of not only freeing up real estate on PCIe/104-Express peripherals as illustrated in the figure above, but perhaps more importantly, it can also reduce cost significantly for many peripherals for which the additional 2 banks for the x16 PEG have been largely superfluous and a relatively high percentage of the overall board cost. This is encouraging for our end-customers and peripheral vendors but also helps PC/104 remain cost competitive against competitive technologies." according to JC Ramirez, Product Manager, ADL Embedded Solutions.