Answers Database
PROM XC18V00: What is the function of the CF# pin.
Record #7472
Problem Title:
PROM XC18V00: What is the function of the CF# pin.
Problem Description:
Urgency: Standard
General Description:
What is the function of the CF# pin on the XC18V00 devices?
Solution 1:
The CF# pin allows a soft restart of the FPGA without powering down the
FPGA by cycling the PROGRAM# pin low. It is controlled through JTAG
instruction called CONFIG. See the datasheet for more information.
The following situation is the typical use of this pin.
+ FPGA is configured and functioning in circuit.
+ Reprogram the 1800 in circuit via JTAG with new
bitstream while the FPGA is still functioning.
+ Execute CONFIG instruction on 1800 device, which will
toggle the CF# pin on the 1800.
+ FPGA is reset and configured with new bitstream from 1800.
NOTE: The CF# pin from the 1800 must be connected to the
PROGRAM# pin on the FPGA to take advantage of this feature.
Solution 2:
The CF# pin is open drain. It is driven low then released when issued
the JTAG CONFIG command. At all other times this pin is tri-stated.
End of Record #7472 - Last Modified: 01/20/00 13:47 |
