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AR# 34953

Spartan-3/-3E - What does "legacy input error" in the status register mean?


The following error occurs when I read the status register of Spartan-3/-3E devices after a configuration attempt:

CRC error : 0
Decryptor security set : 0
DCM locked : 1
DCI matched : 1
legacy input error : 1
status of GTS_CFG_B : 0
status of GWE : 0
status of GHIGH : 0
value of MODE pin M0 : 1
value of MODE pin M1 : 0
value of MODE pin M2 : 0
value of CFG_RDY (INIT_B) : 0
DONEIN input from DONE pin : 0
IDCODE not validated while trying to write FDRI : 0
write FDRI issued before or after decrypt operation: 0
Decryptor keys not used in proper sequence : 0

What does "legacy input error" mean, and what should I do to eliminate the error?


This error occurs when serial data is loaded too fast. If CCLK runs too fast, the internal logic cannot process the coming data.

You can attempt to slow down the configuration frequency to eliminate the error.

The legacy input error can also occur when there is ground/Vcc bounce on the power rails, even if CCLK is very slow.

AR# 34953
Date 12/15/2012
Status Active
Type General Article
  • Spartan-3E
  • Spartan-3
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