On Thu, 06 Oct 2011 11:00:04 +0200, [email protected]
wrote:
I think the FPGA should already have those internally (the same
pull-ups that make the LEDs go dimly lit when the FPGA is
unconfigured). But maybe there are glitches or something?
ug380 seems to say there are:
"FOE_B Output DualPurpose
Active-Low flash output enable. This output is actively driven Low
during configuration and 3-stated after configuration. It has a weak
pull-up resistor during configuration. By default, this signal has a
weak
pull-down resistor after configuration.
FWE_B Output DualPurpose
Active-Low flash write enable. This output is actively driven High
during configuration and 3-stated after configuration. It has a weak
pull-up resistor during configuration. By default, this signal has a
weak
pull-down resistor after configuration."
On the other hand, in document revision 2.0 (see Revision History),
they specifically _added_ external pull-ups, so there is probably a
reason for this. We can just stick to the recommended Xilinx schematics
and add those resistors on rev4 boards.
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