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AdvancedTCA, ATCA (Advanced Telecom Computing Architecture) is the latest standard for carrier-grade switching systems developed by the PICMG (PCI Industrial Computers Manufacturers Group) organization. The AdvancedTCA telecommunication system standard has the most extensive input of any architecture standard to date and is being backed by more than 100 companies including many of the large players such as Intel, Lucent, and Motorola. The advantages of designing a standardized chassis are quite well-known. Different components from different vendors can be tied together and are guaranteed to operate. In addition, common components can be used in several different systems without the need for re-design. But once you decide that you are going to design an ATCA-compliant framework, how do you cool it? The ATCA specification has addressed cooling telecommunication components, at least at the architect’s level.
Integrating Fan Control with Advanced Telecom Computing Architecture (AdvancedTCA, ATCA)
Figure 1 – Intelligent FRU
Figure 2 – Managed FRU
A Managed FRU fan tray could use virtually any existing fan tray and integrate it into an ATCA chassis. The fan tray controls the fan speed and power regulation, while another component in the system manages communication with the rest of the system and inventory information. The advantages of such a design are: fewer communication requirements, which can lower cost; the ability to use fan trays from existing designs; and, allowing the fan tray to be customized outside the ATCA specification for the specific requirements of the chassis. The only set requirements become handling the input voltage range of 34 – 76 VDC and related features, and having another component in the system to maintain inventory data. A sample implementation is shown in Figure 2. The power and regulation sections of the fan tray are basically the same.
It is the control section that is different. While a much less complex control and interface section is required, the system must have specialized hardware to interface to the fan tray. Some data would need to be reported as not available or gathered outside the tray. A separate temperature sensor would be an example of how this could be done. Another approach could use a single private I2C bus, as shown in Figure 3, which could give nearly all the features of the IPMB implementation of Figure 1 with less fan controller hardware and firmware but added system hardware and software. This system could even store the inventory and capabilities data in its own EEPROM, but another controller would need to access the information because it would not be available on the IPMB.
Figure 3 – Managed FRU with private I2C bus
As with any engineering challenge, designing the cooling interface of an ATCA chassis is about weighing one advantage against another to give the best system performance. There are performance and cost advantages to either approach above. While in one system it may be infeasible to add a separate communications bus to the fan controller, another system may have an un-utilized private bus and overhead available to manage the fan tray.
Requirement Summary
| Intelligent FRU | Managed FRU |
|---|---|
| Standard Interface: Software | Custom Interface: Hardware and Software |
| Uses Existing Shelf Manager Resources | Requires System to Manage Fan Tray |
| Fan Tray requires IPMB Hardware and Software | Â |
