Randa Zarrouk

State FlipFlops for PLU (LPC55S69)

Discussion created by Randa Zarrouk on Sep 26, 2019
Latest reply on Oct 9, 2019 by xiangjun.rong


I have some questions regarding the FF deployment in the PLU module:


Point 1:

"The outputs of up to four of the LUTs can be captured in one of the four state flip-flops" UM


Do this mean that it is only possible to use the FFs with LUT0, LUT1, LUT2 and LUT3 ? Since in the configuration tool there is a warning to use assign the FF to the LUT with the same index (also when mapping it only show FF with index from 0 to 4) . 


In addition, does it mean that: every flipflop is able to get its input from only one LUT output (since it is only 1bit storage) and the state index is the index of the respective LUT? 

Point 2:

"which can then be used as primary outputs and/or connected to the inputs of other LUTs." UM

Using the configuration tool (direct, LUT-based design), I was trying to use the output of one of the LUTs as input for a FF and in the same time as an input for and other LUT (also to one of the primary PLU outputs) but the was only possible to be done from one entity to just an other entity, not more than one in the same time (Yallow arrow in the figure below). 

I also wanted use the output of the FF as a primary PLU outputs and in the same time an input to one of the LUTs but was not possible, it was either possible to wire it to the LUT input or one of the primary PLU outputs (Red arrow in the figure below).
Any idea?

Thank you for your help.