How do I determine whether an LVDS/LVPECL pin pair can be used as both synchronous and asynchronous output for a specific device and package combination?
Reference the Virtex-E data sheet at:
The Virtex-E 1.8V FPGA Pin-out Tables -> Virtex-E Package Pin-outs -> FG1156 Fine-Pitch Ball Grid Array Package, Table 28 lists pin AF4 in Bank 6 as "IO_L274P_Y".
In the same data sheet, in the Low Voltage Differential Signals section (Table 2 on page 3), it states the following:
"IO_L#(P/N)_Y represents a general I/O or a synchronous input/output differential signal, or a part-dependent asynchronous output differential signal."
Pin-out Table 28 is general for V1000E, V1600E, V2000E, V2600E, and V3200E.
How do I determine if I can use pin AF4 as asynchronous output in V2600?
Table 29 on page 137- 145 lists the differential pin pairs for the FG1156 package. The "AO" (asynchronous output) column of this table lists devices for which a specific pair can be used as an asynchronous output.
For example, for pin AF4 listed on page 144, pair 274, the "AO" column contains 2600 and 1000. This means that pin AF4 can be used as an asynchronous output in V1000EFG1156 and V2600EFG1156. It cannot be used as an asynchronous output in V1600EFG1156 and V2000EFG1156.
In the individual package file, if a pin is listed as "IO_L#(P/N)_Y", it can be used as an asynchronous output.
For example, in the V2600EFG1156 package file (v2600efg1156.pkg), pin AF4 is listed as IO_L274P_Y. Consequently, pin AF4 is a valid asynchronous output.
In the V2000EFG1156 package file (v2000efg1156.pkg), the same Pin AF4 is listed as "IO_L274P". Consequently, pin AF4 cannot be used as an asynchronous output in this package.
The same applies to Spartan-IIE pin-outs.
The best way to determine what pins are I/O is to view the package file for the specific device and package information. The package file can be obtained through one of the following methods:
1. Run "partgen -v <device_package_combination>" on a command prompt with the Xilinx software installed.
partgen -v v2600efg1156
The <device>.pkg file will be copied into your directory.
2. Access the package files on the web:
For Spartan-IIE, use the "partgen" command.