|
马上注册,结交更多好友,享用更多功能,让你轻松玩转社区。
您需要 登录 才可以下载或查看,没有账号?注册
x
Hi, all
plz help me with the following issue, thanks in advance.
when implementing the layout, no setup-violation is issued during setup & floorplan, however, when placement is done, things goes
differently:
and here is the timing report:
****************************************
Report : timing -path full_clock_expanded -delay max -slack_lesser_than -5.00 -max_paths 1 -transition_time
Design : design
Scenario(s): func_osc_48M
Version: E-2010.12-ICC-SP3-1
Date : Sat Nov 26 19:11:15 2011
****************************************
Startpoint: u_design_core/u_sub1/sub2_r_o_reg
(rising edge-triggered flip-flop clocked by designter_clk_dec)
Endpoint: R_O_PAD (output port clocked by designter_clk_dec)
Scenario: func_osc_48M
Path Group: designter_clk_dec
Path Type: max
Point Trans Incr Path Voltage
------------------------------------------------------------------------------------
clock designter_clk_dec (rise edge) 0.00 0.00
clock network delay (ideal) 3.00 3.00
u_design_core/u_sub1/sub2_r_o_reg/CK (SDFPSBNRQ1)
1.00 0.00 # 3.00 r 4.50
u_design_core/u_sub1/sub2_r_o_reg/Q (SDFPSBNRQ1)
43.74 20.36 23.36 f 4.50
u_design_core/u_sub1/sub2_r_o (sub1) 0.00 23.36 f 4.50
u_design_core/r_o (design_core) 0.00 23.36 f 4.50
u_io_pad/r_o_cc (io_pad) 0.00 23.36 f 4.50
u_io_pad/r_o/PAD (POT24) 4.60 9.69 * 33.04 f 4.50
u_io_pad/r_o_pad (io_pad) 0.00 33.04 f 4.50
R_O_PAD (out) 4.60 0.00 * 33.04 f 4.50
data arrival time 33.04
clock designter_clk_dec (rise edge) 20.00 20.00
clock network delay (ideal) 3.00 23.00
clock uncertainty -3.10 19.90
output external delay -8.00 11.90
data required time 11.90
------------------------------------------------------------------------------------
data required time 11.90
data arrival time -33.04
------------------------------------------------------------------------------------
slack (VIOLATED) -21.14
and from above CLK to Q is more than 20ns, becaused of the unexpected transition time, and now I have two questions:
1. u_design_core/u_sub1/sub2_r_o_reg/CK (SDFPSBNRQ1)
1.00 0.00 # 3.00 r 4.50
u_design_core/u_sub1/sub2_r_o_reg/Q (SDFPSBNRQ1)
43.74 20.36 23.36 f 4.50
what's the transition time above, eg, the 43.74 means the transition time of the pin "sub2_r_o_reg/D"(data input port)? why is it so big?
2.why does this happen and how to fix this issue??
regards,
henry |
|