7I92 13
OPERATION
FREE FLASH MEMORY SPACE
Fifteen 64K byte blocks of flash memory space are free when both user and fallback
configurations are installed. These free blocks can be used for storing user data.
FALLBACK INDICATION
Mesa’s supplied fallback configurations blink the red INIT LED on the top right hand
side of the card if the primary configuration fails and the fallback configuration loaded
successfully. If this happens it means the user configuration is corrupted or not a proper
configuration for the 7I92s FPGA. This can be fixed by running the configuration utility and
re-writing the user configuration.
FAILURE TO CONFIGURE
The 7I92 should configure its FPGA within a fraction of a second of power
application. If the FPGA card fails to configure, the red /DONE LED CR2 will remain
illuminated. If this happens the 7I92s EEPROM must be re-programmed via the JTAG
connector or (faster) JTAG FPGA load followed by Ethernet EEPROM update.
CLOCK SIGNALS
The 7I92 has a single 50 MHz clock signal from an on card crystal oscillator. The
clock a can be multiplied and divided by the FPGAs clock generator block to generate a
wide range of internal clock signals. The 50 MHz clock is also used to generate the 25MHz
clock for the Ethernet interface chip.
