Just had my first taste of the company supplied software from Gowin Semicon= ductor. It's ok. Documentation is terrible being not much more than a lis= ting of the menu items. Lots of features are lacking.=20 My test file is a simple 11 bit down counter described three slightly diffe= rent ways to see what might be the best for my current design which is goin= g to have a lot of counters. Typically they need an enable input to kick t= he counter off and a carry output to indicate the counter has reached it's = terminal count (zero). A bit of combining enable logic and it's ready to a= ct as the main state machine control for nearly everything I'm going to hav= e to do. =20 To be able to halt the counter the carry output is directly carry driven, n= ot registered. So that means the counter has to be a signal... I would hav= e liked encapsulating it in the process as a variable. So the process just= has the counter being incremented on the enable input combined with the in= verted carry. =20 In a couple of versions I use a procedure to generate nxt_cnt and carry_out= as a concurrent statement, one using unsigned and one using integers, the = carry being generated by adding a msb to the adder in each case. The third= version uses an integer for the counter and does a modular subtract of one= in the process. The carry is a concurrent statement testing for the count= er being equal to zero. To my surprise when tested on Synplify for Lattice= , all three gave the same logic! So if testing for zero can be equated to = a carry out of a decrementer it's all good. =20 But it's not all good. The Gowin software seems to make a dog's breakfast = out of it and adds a bunch of logic that shouldn't be needed. They don't h= ave an RTL view feature, so it's hard to tell just what they've done. For = one the zero test is being done as a zero test by oring every bit. I can't= figure out the rest without drawing the schematic or something. It is usi= ng the same number of LUTs, but also listed is 10 ALUs which seem to be LUT= s used as adders. I would expect to see 33 or 36 of those, not 10!=20 Maybe the FAE can help.=20 --=20 Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Gowin Synthesis Software
Started by ●October 17, 2020