Answers Database

XCHECKER: What should the RST pin be connected to in XC4000 or XC5200 devices?


Record #2739

Product Family:  Hardware

Product Line:  Other

Problem Title:
XCHECKER: What should the RST pin be connected to in XC4000 or XC5200
devices?



Problem Description:
Keywords: xchecker, reset, RST, 4k, 4000, 5200

Urgency: Standard

General Description:
In Hardware Debugger Reference/user guide 4-7 (10/95),
it is stated that cable connection to RST for xc4000 is
'User-programmable connection; requires a 10-50 kohm pullup
resistor.

What should this pin be connected to in configuring 4000
devices?


Solution 1:

Resolution:

The RESET pin does not need to be connected for configuration.
It can be used during an in-circuit debug to reset the flip
flops in the device.

To access the global reset in the device, the Startup symbol
must be instantiated in the design.  Connect an inverter to
the reset pin on the startup signal.  Connect an ibuf to the
inverter and an ipad to the ibuf.  Assign the pad to a pin
location.  Tie the RST pin on the XCHECKER cable to the
assigned pin.

The inverter is required, because the XChecker RST pin
generates an active low signal.



End of Record #2739