Fabric Front Blade Port Mapping; Bcm84740 Configuration Flash; Transmitter Control; Figure 4-5 Fabric 40Gb Interconnect - SMART Embedded Computing RTM-ATCA-F140 Series Installation & Use Manual

Functional Description
includes 0.1μF AC-coupling capacitors on the XLAUI inputs from the front blade. Similarly
capacitors are expected to be provided on the front blade for signals from the RTM. The
QSFP+ specification requires AC-coupling capacitors in the module so they are not needed
on the blade SFI interface.

Figure 4-5 Fabric 40Gb Interconnect

4.6.2

Fabric Front Blade Port Mapping

Each fabric switch port on the front blade consists of four SERDES pairs. The four fabric
channel XLAUI pairs connect to front blade port FIX_P14. This is a dedicated port on the
ATCA-F140 front blade fabric switch.
4.6.3

BCM84740 Configuration Flash

The BCM84740 requires an external SPI flash to store microcode for the internal
microcontroller. A single SPI flash is connected to the FPGA and the SPI bus from the
BCM84740 is similarly connected to the FPGA. Register settings in the FPGA allow the
BCM84740 to connect to the SPI flash as well as provide a programming port.
4.6.4

Transmitter Control

QSFP+ does not define a hardware signal for transmitter control. Software controls the
transmitter via byte 86 in the QSFP+ memory map. Refer to the QSFP+ Specification for
further detail.
The TXONOFF signal on the BCM84740 is connected to the RTM FPGA which allows it to
be driven under software control. When asserted, this signal causes the PHY to drive
LPMODE to the QSFP+ site. This places the PHY and QSFP+ module into low-power
mode but may not actually disable the QSFP+ transmitters, according to the QSFP+
specification. Transmitter control should be performed through the software method
detailed above.
64 RTM-ATCA-F140 Series Installation and Use (6806800M97M)
Functional Description