PCIe CableMod

Overview

Some EVMs such as AM571X IDK, AM572X IDK, and K2G EVM have standard female x1 or x4 connectors as typically found in a root complex (RC) like a PC. These can be directly used to connect off the shelf endpoints (EP). However, when using PCIe as interconnect between TI devices such as the RTOS PCIe example, a x1 or x4 male-male cross cable is required. This cable MUST NOT have clock and power signals connected otherwise the EVMs could be damaged. The rest of this page covers cables we have seen or used and what modifications are required to avoid EVM damage.

Adex Pre-Built Cables without Power/Clock

One vendor Adex Electronics has pre-modified part numbers in their catalog:

• PE-FLEX1-G2-MMCX-12-TI1: 1-lane cross cable
• PE-FLEX4-G2-MMCX-12-TI1: 4-lane cross cable

The "TI1" indicates removal of clock and power jumpers (resistors) and should be in their catalog. We have tested using these cables, but any PCIE cross cable without power and clock lines should work.

Modification of Adex Cables without TI1 Suffix

The modifications are identical for the 1 lane and 4 lane cables.

There are 2 resistors/jumpers that need to be removed from the connector labelled "B-SIDE" with the part number printed. They are labelled 12V and 3.3V. On B-SIDE, leave intact the two jumpers/resistors marked "X16 X1". On the "A-SIDE" of the same connector, remove the jumper/resistor labeled 3.3V and the two clock (CK- and CK+) jumpers/resistors. Leave the RST jumper/resistor intact. Leave

Photo of A-SIDE of -TI1 modified 1-lane cable:

Photo of B-SIDE of -TI1 modified 1-lane cable:

Modification of Samtec PCIE-036-0200-EC-EC Cable

The setup that we used is a combination of a male-male cross cable and a male-female extender in order to have sufficient length to avoid stressing connectors.

Specifically for PCIE-036-0200-EC-EC, the following picture shows which traces to cut in order to permanently disconnect the clock signal. User accepts all risks for making modifications to this cable. We used hobby knife to modify the cable.