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Issue regarding Clock Tree Synthesis

Hi, while performing clock tree synthesis, one has to provide list of inverters and buffers in "generate clock specs" by selecting from the list of available cells. this list is missing in my case. any ideas how to get the list.?

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Arslan over 12 years ago

the tool should automatically select clock buffers, but in my case it is not doing that. And even if I manually write .ctstch file and specify buffers, it gives following warning and error
**WARN: (ENCCK-994):    Cell BUF_X0P5B_A12TL_C31 has no timing arc. Check The timing libraries.
**ERROR: (ENCCK-724):
Buffer BUF_X0P5B_A12TL_C31 specified in the clock tree specification file is invalid.
I have checked and this cell is present both in .lib and macro lef.
regarding the warning, following data is present in .lib and as far as I think timing arc is present.

pin(Y) {
      direction : output ;
      function : "A" ;
      max_capacitance : 0.0559642 ;
      max_transition : 0.629333 ;
      min_capacitance : 0.0001 ;
      output_voltage : default ;
      related_ground_pin : VSS ;
      related_power_pin : VDD ;
      power_down_function : "!VDD + VSS" ;

      internal_power() {
        related_pin : "A" ;

        fall_power(pwr_tin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.000799615, 0.000809414, 0.000804709, 0.000799901, 0.000796933, 0.000794658, 0.000793265",\
                 "0.000779447, 0.000791893, 0.000794127, 0.000789831, 0.00078605, 0.00078341, 0.000781609",\
                 "0.00075481, 0.000764512, 0.000771666, 0.000772847, 0.000771287, 0.000769781, 0.000768644",\
                 "0.000740172, 0.000748833, 0.000758996, 0.000761591, 0.000762006, 0.000761375, 0.000760505",\
                 "0.000733962, 0.000740326, 0.000751239, 0.000757472, 0.000757939, 0.000758445, 0.000758127",\
                 "0.000732756, 0.00073781, 0.000748783, 0.000756138, 0.000759203, 0.000758949, 0.000759207",\
                 "0.000737063, 0.000742102, 0.000751108, 0.000758366, 0.000763561, 0.000764869, 0.000764537");
        }

        rise_power(pwr_tin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.000398047, 0.000399094, 0.000368668, 0.000309951, 0.000217467, 8.96784e-05, -9.89654e-05",\
                 "0.000379525, 0.000381884, 0.00035439, 0.000296803, 0.000208909, 8.21009e-05, -9.57076e-05",\
                 "0.000359822, 0.000369113, 0.000336634, 0.000283114, 0.000192421, 6.7156e-05, -0.000111223",\
                 "0.000347169, 0.000355357, 0.00036125, 0.000273792, 0.000183245, 6.04281e-05, -0.000124907",\
                 "0.000339577, 0.000346178, 0.000354397, 0.000354857, 0.000183655, 4.95099e-05, -0.000117814",\
                 "0.000337152, 0.000341429, 0.000348397, 0.000346551, 0.000330806, 6.69343e-05, -0.000116624",\
                 "0.000338414, 0.00034255, 0.00034286, 0.000347778, 0.000350767, 0.000347991, -3.63895e-05");
        }
      }

      timing() {
        related_pin : "A" ;
        timing_sense : positive_unate ;
        timing_type : combinational ;

        cell_fall(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.0158512, 0.0223217, 0.0437717, 0.0847096, 0.148543, 0.238134, 0.356032",\
                 "0.0215605, 0.0280732, 0.0496417, 0.0905883, 0.15441, 0.24399, 0.361885",\
                 "0.0380775, 0.044788, 0.0664424, 0.107434, 0.17126, 0.260836, 0.378723",\
                 "0.0616066, 0.0692005, 0.0909026, 0.131875, 0.195689, 0.285233, 0.403102",\
                 "0.0895357, 0.0991638, 0.121553, 0.162355, 0.22609, 0.315587, 0.433413",\
                 "0.120292, 0.132682, 0.157371, 0.197968, 0.261518, 0.350912, 0.468664",\
                 "0.152779, 0.168385, 0.197076, 0.237967, 0.301225, 0.390433, 0.508057");
        }

        cell_rise(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.0200719, 0.0251704, 0.0402318, 0.0685235, 0.112603, 0.174458, 0.255851",\
                 "0.0255913, 0.0306991, 0.0458071, 0.0741014, 0.118175, 0.180023, 0.261416",\
                 "0.0426747, 0.0480412, 0.0633147, 0.0916258, 0.135679, 0.197513, 0.278893",\
                 "0.066668, 0.0727648, 0.0883858, 0.116703, 0.16075, 0.222548, 0.303888",\
                 "0.094421, 0.101884, 0.118338, 0.146575, 0.190562, 0.25233, 0.333632",\
                 "0.124006, 0.1334, 0.151575, 0.179844, 0.223647, 0.285321, 0.366576",\
                 "0.154086, 0.165775, 0.186688, 0.215439, 0.258964, 0.32046, 0.401606");
        }

        fall_transition(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.00774636, 0.0185995, 0.0577129, 0.132635, 0.249353, 0.413141, 0.628703",\
                 "0.00785682, 0.0186233, 0.0577083, 0.132623, 0.249377, 0.413176, 0.628734",\
                 "0.00920592, 0.019244, 0.0578494, 0.132662, 0.249379, 0.413151, 0.628711",\
                 "0.0130111, 0.0215641, 0.0583874, 0.132889, 0.249473, 0.41318, 0.628679",\
                 "0.019134, 0.0269453, 0.0600547, 0.133387, 0.249743, 0.41337, 0.628744",\
                 "0.0270202, 0.035272, 0.0642992, 0.134499, 0.250249, 0.413648, 0.628994",\
                 "0.0365, 0.0457262, 0.0721991, 0.13721, 0.251165, 0.414188, 0.629311");
        }

        rise_transition(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.00832464, 0.0157314, 0.0433071, 0.0975357, 0.182286, 0.301218, 0.457735",\
                 "0.00836245, 0.0157446, 0.043311, 0.0975335, 0.182272, 0.301202, 0.457707",\
                 "0.00977667, 0.0167199, 0.0436751, 0.0976212, 0.182299, 0.301206, 0.457723",\
                 "0.0133544, 0.0194572, 0.0448837, 0.0981831, 0.182608, 0.301347, 0.457773",\
                 "0.0191592, 0.0244967, 0.0474023, 0.0992111, 0.183248, 0.30182, 0.458047",\
                 "0.0268718, 0.032019, 0.0520368, 0.101128, 0.184192, 0.302516, 0.458584",\
                 "0.0362388, 0.0416758, 0.0594135, 0.104635, 0.185688, 0.303445, 0.459354");
        }
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Reply

Arslan over 12 years ago

the tool should automatically select clock buffers, but in my case it is not doing that. And even if I manually write .ctstch file and specify buffers, it gives following warning and error
**WARN: (ENCCK-994):    Cell BUF_X0P5B_A12TL_C31 has no timing arc. Check The timing libraries.
**ERROR: (ENCCK-724):
Buffer BUF_X0P5B_A12TL_C31 specified in the clock tree specification file is invalid.
I have checked and this cell is present both in .lib and macro lef.
regarding the warning, following data is present in .lib and as far as I think timing arc is present.

pin(Y) {
      direction : output ;
      function : "A" ;
      max_capacitance : 0.0559642 ;
      max_transition : 0.629333 ;
      min_capacitance : 0.0001 ;
      output_voltage : default ;
      related_ground_pin : VSS ;
      related_power_pin : VDD ;
      power_down_function : "!VDD + VSS" ;

      internal_power() {
        related_pin : "A" ;

        fall_power(pwr_tin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.000799615, 0.000809414, 0.000804709, 0.000799901, 0.000796933, 0.000794658, 0.000793265",\
                 "0.000779447, 0.000791893, 0.000794127, 0.000789831, 0.00078605, 0.00078341, 0.000781609",\
                 "0.00075481, 0.000764512, 0.000771666, 0.000772847, 0.000771287, 0.000769781, 0.000768644",\
                 "0.000740172, 0.000748833, 0.000758996, 0.000761591, 0.000762006, 0.000761375, 0.000760505",\
                 "0.000733962, 0.000740326, 0.000751239, 0.000757472, 0.000757939, 0.000758445, 0.000758127",\
                 "0.000732756, 0.00073781, 0.000748783, 0.000756138, 0.000759203, 0.000758949, 0.000759207",\
                 "0.000737063, 0.000742102, 0.000751108, 0.000758366, 0.000763561, 0.000764869, 0.000764537");
        }

        rise_power(pwr_tin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.000398047, 0.000399094, 0.000368668, 0.000309951, 0.000217467, 8.96784e-05, -9.89654e-05",\
                 "0.000379525, 0.000381884, 0.00035439, 0.000296803, 0.000208909, 8.21009e-05, -9.57076e-05",\
                 "0.000359822, 0.000369113, 0.000336634, 0.000283114, 0.000192421, 6.7156e-05, -0.000111223",\
                 "0.000347169, 0.000355357, 0.00036125, 0.000273792, 0.000183245, 6.04281e-05, -0.000124907",\
                 "0.000339577, 0.000346178, 0.000354397, 0.000354857, 0.000183655, 4.95099e-05, -0.000117814",\
                 "0.000337152, 0.000341429, 0.000348397, 0.000346551, 0.000330806, 6.69343e-05, -0.000116624",\
                 "0.000338414, 0.00034255, 0.00034286, 0.000347778, 0.000350767, 0.000347991, -3.63895e-05");
        }
      }

      timing() {
        related_pin : "A" ;
        timing_sense : positive_unate ;
        timing_type : combinational ;

        cell_fall(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.0158512, 0.0223217, 0.0437717, 0.0847096, 0.148543, 0.238134, 0.356032",\
                 "0.0215605, 0.0280732, 0.0496417, 0.0905883, 0.15441, 0.24399, 0.361885",\
                 "0.0380775, 0.044788, 0.0664424, 0.107434, 0.17126, 0.260836, 0.378723",\
                 "0.0616066, 0.0692005, 0.0909026, 0.131875, 0.195689, 0.285233, 0.403102",\
                 "0.0895357, 0.0991638, 0.121553, 0.162355, 0.22609, 0.315587, 0.433413",\
                 "0.120292, 0.132682, 0.157371, 0.197968, 0.261518, 0.350912, 0.468664",\
                 "0.152779, 0.168385, 0.197076, 0.237967, 0.301225, 0.390433, 0.508057");
        }

        cell_rise(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.0200719, 0.0251704, 0.0402318, 0.0685235, 0.112603, 0.174458, 0.255851",\
                 "0.0255913, 0.0306991, 0.0458071, 0.0741014, 0.118175, 0.180023, 0.261416",\
                 "0.0426747, 0.0480412, 0.0633147, 0.0916258, 0.135679, 0.197513, 0.278893",\
                 "0.066668, 0.0727648, 0.0883858, 0.116703, 0.16075, 0.222548, 0.303888",\
                 "0.094421, 0.101884, 0.118338, 0.146575, 0.190562, 0.25233, 0.333632",\
                 "0.124006, 0.1334, 0.151575, 0.179844, 0.223647, 0.285321, 0.366576",\
                 "0.154086, 0.165775, 0.186688, 0.215439, 0.258964, 0.32046, 0.401606");
        }

        fall_transition(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.00774636, 0.0185995, 0.0577129, 0.132635, 0.249353, 0.413141, 0.628703",\
                 "0.00785682, 0.0186233, 0.0577083, 0.132623, 0.249377, 0.413176, 0.628734",\
                 "0.00920592, 0.019244, 0.0578494, 0.132662, 0.249379, 0.413151, 0.628711",\
                 "0.0130111, 0.0215641, 0.0583874, 0.132889, 0.249473, 0.41318, 0.628679",\
                 "0.019134, 0.0269453, 0.0600547, 0.133387, 0.249743, 0.41337, 0.628744",\
                 "0.0270202, 0.035272, 0.0642992, 0.134499, 0.250249, 0.413648, 0.628994",\
                 "0.0365, 0.0457262, 0.0721991, 0.13721, 0.251165, 0.414188, 0.629311");
        }

        rise_transition(tmg_ntin_oload_7x7) {
          index_1("0.00221333, 0.0134941, 0.0530922, 0.12871, \
                  0.24652, 0.41182, 0.629333");
          index_2("0.0001, 0.0011049, 0.00463232, 0.0113684, \
                  0.021863, 0.036588, 0.0559642");
          values("0.00832464, 0.0157314, 0.0433071, 0.0975357, 0.182286, 0.301218, 0.457735",\
                 "0.00836245, 0.0157446, 0.043311, 0.0975335, 0.182272, 0.301202, 0.457707",\
                 "0.00977667, 0.0167199, 0.0436751, 0.0976212, 0.182299, 0.301206, 0.457723",\
                 "0.0133544, 0.0194572, 0.0448837, 0.0981831, 0.182608, 0.301347, 0.457773",\
                 "0.0191592, 0.0244967, 0.0474023, 0.0992111, 0.183248, 0.30182, 0.458047",\
                 "0.0268718, 0.032019, 0.0520368, 0.101128, 0.184192, 0.302516, 0.458584",\
                 "0.0362388, 0.0416758, 0.0594135, 0.104635, 0.185688, 0.303445, 0.459354");
        }
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