目录
引言
背景知识
多时钟设计
DC 输出文件分析
实际操作
设计源码
综合脚本
综合网表
SDF文件
SDC文件
REPORT文件
引言
本篇继续学习 DC的基本使用。本篇主要学习 DC 综合之后的效果分析，多同步时钟设计以及 DC 综合完成之后的各种输出文件。
前文链接：
Design Compiler工具学习笔记（1）
Design Compiler工具学习笔记（2）
Design Compiler工具学习笔记（3）
Design Compiler工具学习笔记（4）
Design Compiler工具学习笔记（5）
Design Compiler工具学习笔记（6）
背景知识
多时钟设计
多周期约束时，对应的设计代码也需要修改。比如使能信号、数据有效信号需要延迟相应的时间。
DC 输出文件分析
实际操作
设计源码
简单的设计文件：做一个9级延迟的寄存器链。源代码：
module MY_DESIGN ( input I_CLK_100M, input I_RSTN_100M, input I_DATA, input I_VAL, output O_DATA ); reg [9:0] R_I_DATA; genvar GV_I; generate for(GV_I = 0;GV_I < 10;GV_I = GV_I + 1) begin always @ (posedge I_CLK_100M) begin if(~I_RSTN_100M) begin R_I_DATA[GV_I] <= 0; end else if(GV_I == 0) begin R_I_DATA[GV_I] <= I_DATA & I_VAL; end else begin R_I_DATA[GV_I] <= R_I_DATA[GV_I-1]; end end end endgenerate assign O_DATA = R_I_DATA[9]; endmodule
综合脚本
# |===========================================================
# | Author : Xu Y. B.
# | Date : 2022-11-21
# | Description : tcl script for top design
# |===========================================================
# |===========================================================
# |STEP 1: Read & elaborate the RTL design file list & check
# |===========================================================
set TOP_MODULE MY_DESIGN
analyze -format verilog [list MY_DESIGN.v]
elaborate $TOP_MODULE -architecture verilog
current_design $TOP_MODULE
if {[link] == 0} {
echo "Your Link has errors !";
exit;
}
if {[check_design] == 0} {
echo "Your check design has errors !";
exit;
}
# |===========================================================
# |STEP 2: reset design
# |===========================================================
reset_design
# |===========================================================
# |STEP 3: Write unmapped ddc file
# |===========================================================
uniquify
set uniquify_naming_style "%s_%d"
write -f ddc -hierarchy -output ${UNMAPPED_PATH}/${TOP_MODULE}.ddc
# |===========================================================
# |STEP 4: define clocks
# |===========================================================
# -------------------------- CLK 100MHz ----------------------
set CLK_NAME I_CLK_100M
set CLK_PERIOD 10
set CLK_SKEW [expr {$CLK_PERIOD*0.05}]
set CLK_TRANS [expr {$CLK_PERIOD*0.01}]
set CLK_SRC_LATENCY [expr {$CLK_PERIOD*0.1 }]
set CLK_LATENCY [expr {$CLK_PERIOD*0.1 }]
create_clock -period $CLK_PERIOD [get_ports $CLK_NAME]
set_ideal_network [get_ports $CLK_NAME]
set_dont_touch_network [get_ports $CLK_NAME]
set_drive 0 [get_ports $CLK_NAME]
set_clock_uncertainty -setup $CLK_SKEW [get_clocks $CLK_NAME]
set_clock_transition -max $CLK_TRANS [get_clocks $CLK_NAME]
set_clock_latency -source -max $CLK_SRC_LATENCY [get_clocks $CLK_NAME]
set_clock_latency -max $CLK_LATENCY [get_clocks $CLK_NAME]
# --------------------------- CLK 50MHz ----------------------
# set CLK_NAME_2 I_CLK_50M
# set CLK_PERIOD_2 20
# set CLK_SKEW_2 [expr {$CLK_PERIOD_2*0.05}]
# set CLK_TRANS_2 [expr {$CLK_PERIOD_2*0.01}]
# set CLK_SRC_LATENCY_2 [expr {$CLK_PERIOD_2*0.1 }]
# set CLK_LATENCY_2 [expr {$CLK_PERIOD_2*0.1 }]
# create_clock -period $CLK_PERIOD_2 [get_ports $CLK_NAME_2]
# set_ideal_network [get_ports $CLK_NAME_2]
# set_dont_touch_network [get_ports $CLK_NAME_2]
# set_drive 0 [get_ports $CLK_NAME_2]
# set_clock_uncertainty -setup $CLK_SKEW_2 [get_clocks $CLK_NAME_2]
# set_clock_transition -max $CLK_TRANS_2 [get_clocks $CLK_NAME_2]
# set_clock_latency -source -max $CLK_SRC_LATENCY_2 [get_clocks $CLK_NAME_2]
# set_clock_latency -max $CLK_LATENCY_2 [get_clocks $CLK_NAME_2]
# |===========================================================
# |STEP 5: define reset
# |===========================================================
# ------------------------- RST 1 ----------------------------
set RST_NAME I_RSTN_100M
set_ideal_network [get_ports $RST_NAME]
set_dont_touch_network [get_ports $RST_NAME]
set_drive 0 [get_ports $RST_NAME]
# # ------------------------- RST 2 ----------------------------
# set RST_NAME_2 I_RSTN_50M
# set_ideal_network [get_ports $RST_NAME_2]
# set_dont_touch_network [get_ports $RST_NAME_2]
# set_drive 0 [get_ports $RST_NAME_2]
# |===========================================================
# |STEP 6: set input delay using timing budget
# |Assume a weak cell to drive the input pins
# |===========================================================
set LIB_NAME typical
set WIRE_LOAD_MODEL smic18_wl10
set DRIVE_PIN Y
set OPERATE_CONDITION typical
set ALL_INPUT_EXCEPT_CLK [remove_from_collection [all_inputs] [get_ports "$CLK_NAME"]]
set INPUT_DELAY [expr {$CLK_PERIOD*0.6}]
set_input_delay $INPUT_DELAY -clock $CLK_NAME $ALL_INPUT_EXCEPT_CLK
set_driving_cell -lib_cell ${DRIVE_CELL} -pin ${DRIVE_PIN} $ALL_INPUT_EXCEPT_CLK
# |===========================================================
# |STEP 7: set output delay
# |===========================================================
set OUTPUT_DELAY [expr {$CLK_PERIOD*0.6}]
set MAX_LOAD [expr {[load_of $LIB_NAME/INVX4/A] * 10}]
set_output_delay $OUTPUT_DELAY -clock $CLK_NAME [all_outputs]
set_load [expr {$MAX_LOAD * 3}] [all_outputs]
set_isolate_ports -type buffer [all_outputs]
# |===========================================================
# |STEP 8: set max delay for comb logic
# |===========================================================
# set_input_delay [expr $CLK_PERIOD * 0.1] -clock $CLK_NAME -add_delay [get_ports I_1]
# set_output_delay [expr $CLK_PERIOD * 0.1] -clock $CLK_NAME -add_delay [get_ports O_1]
# |===========================================================
# |STEP 9: set operating condition & wire load model
# |===========================================================
set_operating_conditions -max $OPERATE_CONDITION \
-max_library $LIB_NAME
set auto_wire_load_selection false
set_wire_load_mode top
set_wire_load_model -name $WIRE_LOAD_MODEL \
-library $LIB_NAME
# |===========================================================
# |STEP 10: set area constraint (Let DC try its best)
# |===========================================================
set_max_area 1000
# |===========================================================
# |STEP 11: set DRC constraint
# |===========================================================
# set MAX_CAPACITANCE [expr {[load_of $LIB_NAME/NAND4X2/Y] * 5}]
# set_max_capacitance $MAX_CAPACITANCE $ALL_INPUT_EXCEPT_CLK
# |===========================================================
# |STEP 12: set group path
# |Avoid getting stack on one path
# |===========================================================
group_path -name $CLK_NAME -weight 5 \
-critical_range [expr {$CLK_PERIOD * 0.1}]
group_path -name INPUTS -from [all_inputs] \
-critical_range [expr {$CLK_PERIOD * 0.1}]
group_path -name OUTPUTS -to [all_outputs] \
-critical_range [expr {$CLK_PERIOD * 0.1}]
group_path -name COMBS -from [all_inputs] \
-to [all_outputs] \
-critical_range [expr {$CLK_PERIOD * 0.1}]
report_path_group
# |===========================================================
# |STEP 13: Elimate the multiple-port inter-connect &
# | define name style
# |===========================================================
# set_app_var verilogout_no_tri true
# set_app_var verilogout_show_unconnected_pins true
# set_app_var bus_naming_style {%s[%d]}
# simplify_constants -boundary_optimization
# set_boundary_optimization [current_design] true
# set_fix_multiple_port_nets -all -buffer_constants
# |===========================================================
# |STEP 14: timing exception define
# |===========================================================
# set_false_path -from [get_clocks I_CLK_100M] -to [get_clocks I_CLK_100M]
# set ALL_CLKS [all_clocks]
# foreach_in_collection CUR_CLK $ALL_CLKS
# {
# set OTHER_CLKS [remove_from_collection [all_clocks] $CUR_CLK]
# set_false_path -from $CUR_CLK $OTHER_CLKS
# }
# set_false_path -from [get_clocks I_CLK_100M] -to [get_clocks I_CLK_100M]
# set_false_path -from [get_clocks I_CLK_100M] -to [get_clocks I_CLK_100M]
# set_disable_timing TOP/U1 -from a -to y
# set_case_analysis 0 [get_ports sel_i]
# set_multicycle_path -setup 6 -from FFA/CP -through ADD/out -to FFB/D
# set_multicycle_path -hold 5 -from FFA/CP -through ADD/out -to FFB/D
# set_multicycle_path -setup 2 -to FFB/D
# set_multicycle_path -hold 1 -to FFB/D
# |===========================================================
# |STEP 15: compile flow
# |===========================================================
# ungroup -flatten -all
# 1st-pass compile
# compile -map_effort high -area_effort high
# compile -map_effort high -area_effort high -boundary_optimization
compile -map_effort high -area_effort high
# simplify_constants -boundary_optimization
# set_fix_multiple_port_nets -all -buffer_constants
# compile -map_effort high -area_effort high -incremental_mapping -scan
# 2nd-pass compile
# compile -map_effort high -area_effort high -incremental_mapping -boundary_optimization
# compile_ultra -incr
# |===========================================================
# |STEP 16: write post-process files
# |===========================================================
change_names -rules verilog -hierarchy
remove-unconnected_ports [get_cells -hier *] -blast_buses
# Write the mapped files
write -f ddc -output $MAPPED_PATH/${TOP_MODULE}.ddc
write -f verilog -hierarchy -output $MAPPED_PATH/${TOP_MODULE}.v
write_sdc -version 1.7 $MAPPED_PATH/${TOP_MODULE}.sdc
write_sdf -version 2.1 $MAPPED_PATH/${TOP_MODULE}.sdf
# |===========================================================
# |STEP 17: generate report files
# |===========================================================
# Get report file
redirect -tee -file ${REPORT_PATH}/check_design.txt {check_design}
redirect -tee -file ${REPORT_PATH}/check_timing.txt {check_timing}
redirect -tee -file ${REPORT_PATH}/report_constraint.txt {report_constraint -all_violators}
redirect -tee -file ${REPORT_PATH}/check_setup.txt {report_timing -delay_type max}
redirect -tee -file ${REPORT_PATH}/check_hold.txt {report_timing -delay_type min}
redirect -tee -file ${REPORT_PATH}/report_area.txt {report_area}综合网表
打开映射后的 .v 文件：
编译时可以加上 -scan 选项，观察寄存器映射的差别：
SDF文件
里面包含了单元的延迟信息。
SDC文件
里面包含了该设计的所有约束
REPORT文件
可以分别打开进行分析，包括时间、面积等。此处就不一一展开。
至此 DC 的视频学习告一段落，了解了基本的使用技巧。但是功夫还需要磨练，多结合工程进行实践是必不可缺的环节。继续加油~~
