AR# 37648: Spartan-6, DCM_CLKGEN - After changing the M and D via SPI, how long before the LOCK re-asserts?
AR# 37648
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Spartan-6, DCM_CLKGEN - After changing the M and D via SPI, how long before the LOCK re-asserts?
描述
When I perform a simulation of the DCM_CLKGEN and change the M and D via SPI, the LOCK does not de-assert. Should it? Also, how long should it take to re-assert?
解决方案
The is an issue in the unisim and simprim models in ISE 12.2 and earlier software.The LOCK does not de-assert after you change the M and D values. This issue is to be fixed in ISE Design Suite12.3. The correct functionality of the LOCKED signal is described in the Spartan-6 FPGA Clocking Resources User Guide (UG382): http://www.xilinx.com/support/documentation/user_guides/ug382.pdf The LOCK re-asserts after PROGDONE has gone High. The length of time for this to occur is specified as LOCK_FX in the Spartan-6 FPGAData Sheet (DS162): http://www.xilinx.com/support/documentation/data_sheets/ds162.pdf