ADM-XRC-II User Manual
5.9. User I/O Configuration
The ADM-XRC-II is fitted with and IO adapter to provide user I/O capability
via the front panel. This allows many different IO connectors and standards to
be easily supported. Currently the following IO adapter cards are available
5.9.1. User I/O XRM IO34 Front Panel Variant
There are 34 I/O signals available on the front panel connector and these can
be used individually or in pairs. All of these signals are from one bank of the
FPGA and are provided with a VCCo supply voltage of 2.5V or 3.3V selected
by JP1. A link on pins 2-3 selects 2.5V whilst a link on pins 1-2 select 3.3V.
Each pair of I/O signals is routed as shown below.
FPGA IO CON
Rs
Rs
Rs
Rs
Rt
Rt
User[0]
User[1]
User[2]
User[3]
The default manufacturing option is Rs=0R and Rt not fitted. Other options are
available. Rs can be used to provide series damping in point to point
applications but for LVDS is 0R. Rt is required for LVDS inputs to provide the
termination voltage from the line current.
User I/O is presented on a 68 way miniature D connector (of SCSI-2 style)
with interleaved signal and ground pairs as shown below. All of the user pins
are routed in pairs to suit the differential assignments of the FPGA e.g.
user[1:0] are the first up to user[33:32].
1
34
68
35
ADM-XRC-II User Manual
Version 1.5
Page 14