Hi,
Is it possible to programmatically configure pins of an Spartan3 or 3E as ground signals? I mean, not only configure them as input signals, but as real ground signals connected to the ground signal on another PCB.
Regards,
JaaC
Hi,
Is it possible to programmatically configure pins of an Spartan3 or 3E as ground signals? I mean, not only configure them as input signals, but as real ground signals connected to the ground signal on another PCB.
Regards,
JaaC
As outputs driven low, IOBs can be a reasonable ground. It's not a precise ground but similar to adding a low value resistor to your other PCB. If your other device is a low current device (I'm looking at using this scheme for
Yes, an active Low output represents a low impedance to ground, somewhere around 10 Ohm. You can easily measure this by pulling the pin to Vcc through a 100 Ohm resistor, and measuring the pin voltage.
Users have also used such an output in the opposite way: Connect the pin to the pc-board ground, and thus reduce the ground-bounce by providing additional connections between chip ground and pc-board ground. Peter Alfke, Xilinx
Yes, an active Low output represents a low impedance to ground, somewhere around 10 Ohm. You can easily measure this by pulling the pin to Vcc through a 100 Ohm resistor, and measuring the pin voltage.
Users have also used such an output in the opposite way: Connect the pin to the pc-board ground, and thus reduce the ground-bounce by providing additional connections between chip ground and pc-board ground. Peter Alfke, Xilinx
Peter; So this is what happens when a CPLD pin is set as a PGND? =20
-Dave Pollum
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