Fmc Expansion Connector - Xilinx XtremeDSP Spartan-3A DSP Technical Reference Manual

FMC expansion connector

The FMC expansion connector (J13) follows the VITA 57.1 FMC standard (standard to be released at a later
date) and it is used in low-pin-count (LPC) format. The XtremeDSP Spartan-3A DSP Development Board was
designed with a preliminary version of the standard.
When an FMC mezzanine module is intended to be used, the FPGA should access the FMC mezzanine module's
2
I C EEPROM to read the board's information. This information allows the FPGA to set the appropriate I/O
voltages to the FPGA I/Os connected to the FMC expansion connector. The way the board information will be
stored in the FMC mezzanine I
Vita-57.2 standard. The standard should be released soon.
To set the appropriate voltage on the FMC connector, an I
should be written to the volatile register of the digital pot. This register is located at address 0x00 if address 0x02
is set to 0x80.
The following steps are used in configuring the digital pot to the following voltages:
Vout = 1.5 V
1. Configure register 0x2 to value 0x80
2. Configure register 0x0 to value 0x8A
Vout = 1.8 V
1. Configure register 0x2 to value 0x80
2. Configure register 0x0 to value 0x57
Vout= 2.5 V
1. Configure register 0x2 to value 0x80
2. Configure register 0x0 to value 0x1E
Vout = 3.3 V
1. Configure register 0x2 to value 0x80
2. Configure register 0x0 to value 0x00
2
C EEPROM is not defined at this time. A work group is currently developing the
2
C digital pot must be set to a specific value. The value
Hardware overview
29