PLL原语例化使用时常见问题
目录
一、前言
二、常见问题
问题一、综合阶段报错[Synth 8-439]
问题二、综合阶段报错[Synth 8-448]
问题三、在实现阶段DRC报错DRC PDRC-38
问题四、在实现阶段DRC报错DRC PDRC-43
一、前言
在设计中经常会使用PLL的原语进行例化使用，PLL如果直接例化使用将会报错，以PLLE2_ADV为例，vivado版本为2019.1，器件为xc7k480tffv1156，例化的模版如下，下面4个标红的系数需重点关注。
PLLE2_ADV #(
.BANDWIDTH("OPTIMIZED"), // OPTIMIZED, HIGH, LOW
.CLKFBOUT_MULT(5), // Multiply value for all CLKOUT, (2-64)将输出先进行指定倍数的倍频处理
.CLKFBOUT_PHASE(0.0), // Phase offset in degrees of CLKFB, (-360.000-360.000).
// CLKIN_PERIOD: Input clock period in nS to ps resolution (i.e. 33.333 is 30 MHz).
.CLKIN1_PERIOD(0.0),
.CLKIN2_PERIOD(0.0),
// CLKOUT0_DIVIDE - CLKOUT5_DIVIDE: Divide amount for CLKOUT (1-128) 设置输出时钟的分频系数
.CLKOUT0_DIVIDE(1),
.CLKOUT1_DIVIDE(1),
.CLKOUT2_DIVIDE(1),
.CLKOUT3_DIVIDE(1),
.CLKOUT4_DIVIDE(1),
.CLKOUT5_DIVIDE(1),
// CLKOUT0_DUTY_CYCLE - CLKOUT5_DUTY_CYCLE: Duty cycle for CLKOUT outputs (0.001-0.999).设置输出时钟的占空比
.CLKOUT0_DUTY_CYCLE(0.5),
.CLKOUT1_DUTY_CYCLE(0.5),
.CLKOUT2_DUTY_CYCLE(0.5),
.CLKOUT3_DUTY_CYCLE(0.5),
.CLKOUT4_DUTY_CYCLE(0.5),
.CLKOUT5_DUTY_CYCLE(0.5),
// CLKOUT0_PHASE - CLKOUT5_PHASE: Phase offset for CLKOUT outputs (-360.000-360.000).设置输出时钟的相移值
.CLKOUT0_PHASE(0.0),
.CLKOUT1_PHASE(0.0),
.CLKOUT2_PHASE(0.0),
.CLKOUT3_PHASE(0.0),
.CLKOUT4_PHASE(0.0),
.CLKOUT5_PHASE(0.0),
.COMPENSATION("ZHOLD"), // ZHOLD, BUF_IN, EXTERNAL, INTERNAL
.DIVCLK_DIVIDE(1), // Master division value (1-56)
// REF_JITTER: Reference input jitter in UI (0.000-0.999).
.REF_JITTER1(0.0),
.REF_JITTER2(0.0),
.STARTUP_WAIT("FALSE") // Delay DONE until PLL Locks, ("TRUE"/"FALSE")
)
PLLE2_ADV_inst (
// Clock Outputs: 1-bit (each) output: User configurable clock outputs
.CLKOUT0(CLKOUT0), // 1-bit output: CLKOUT0
.CLKOUT1(CLKOUT1), // 1-bit output: CLKOUT1
.CLKOUT2(CLKOUT2), // 1-bit output: CLKOUT2
.CLKOUT3(CLKOUT3), // 1-bit output: CLKOUT3
.CLKOUT4(CLKOUT4), // 1-bit output: CLKOUT4
.CLKOUT5(CLKOUT5), // 1-bit output: CLKOUT5
// DRP Ports: 16-bit (each) output: Dynamic reconfiguration ports
.DO(DO), // 16-bit output: DRP data
.DRDY(DRDY), // 1-bit output: DRP ready
// Feedback Clocks: 1-bit (each) output: Clock feedback ports
.CLKFBOUT(CLKFBOUT), // 1-bit output: Feedback clock
.LOCKED(LOCKED), // 1-bit output: LOCK
// Clock Inputs: 1-bit (each) input: Clock inputs
.CLKIN1(CLKIN1), // 1-bit input: Primary clock
.CLKIN2(CLKIN2), // 1-bit input: Secondary clock
// Control Ports: 1-bit (each) input: PLL control ports
.CLKINSEL(CLKINSEL), // 1-bit input: Clock select, High=CLKIN1 Low=CLKIN2
.PWRDWN(PWRDWN), // 1-bit input: Power-down
.RST(RST), // 1-bit input: Reset
// DRP Ports: 7-bit (each) input: Dynamic reconfiguration ports
.DADDR(DADDR), // 7-bit input: DRP address
.DCLK(DCLK), // 1-bit input: DRP clock
.DEN(DEN), // 1-bit input: DRP enable
.DI(DI), // 16-bit input: DRP data
.DWE(DWE), // 1-bit input: DRP write enable
// Feedback Clocks: 1-bit (each) input: Clock feedback ports
.CLKFBIN(CLKFBIN) // 1-bit input: Feedback clock
);
二、常见问题
工程设计代码，主要关注前面 PLLE2_ADV例化使用的参数配置。
module sdc_constraint
(
input rst_pll,
input d0,
input d1,
output out0,
output out1,
input CLK,
input RSTn,
output SDRAM_CLK,
output [4:0]SDRAM_CMD,
output [13:0]SDRAM_BA,
inout [15:0]SDRAM_DATA,
input CLK1,
input WrEN_Sig,
input RdEN_Sig,
output Done_Sig,
output Busy_Sig,
input Init_Done_Sig,
output Init_Start_Sig,
output [2:0]Func_Start_Sig,
output SDRAM_UDQM,
output SDRAM_LDQM,
input CLK2,
input [3:0]Din,
output [3:0]Dout
);
/***********PLL*****************/
wire CLK0_PLL;
wire CLK1_PLL;
reg ff0_pll,ff1_pll;
reg out0,out1;
PLLE2_ADV
#(
.CLKFBOUT_MULT(5), // Multiply value for all CLKOUT, (2-64)
.CLKOUT0_DIVIDE(2), // Divide amount for CLKOUT0 (1-128)
.CLKOUT0_DUTY_CYCLE(0.3), // Duty cycle for CLKOUT0 (0.001-0.999)
.CLKOUT0_PHASE(0.0),
.CLKOUT1_DIVIDE(3), // Divide amount for CLKOUT0 (1-128)
.CLKOUT1_DUTY_CYCLE(0.7), // Duty cycle for CLKOUT0 (0.001-0.999)
.CLKOUT1_PHASE(0.0)
)
U1
(
.CLKIN1 ( CLK ),
.CLKOUT0 ( CLK0_PLL ),
.CLKOUT1 ( CLK1_PLL )
);
/**********FF0**********/
always@(posedge CLK0_PLL,negedge rst_pll)
if(!rst_pll)
ff0_pll<=0;
else begin
ff0_pll<=d0;
end
assign result0=ff0_pll&Busy_Sig;
always@(posedge CLK0_PLL,negedge rst_pll)
if(!rst_pll)
out0<=0;
else begin
out0<=result0;
end
/**********FF1**********/
always@(posedge CLK1_PLL,negedge rst_pll)
if(!rst_pll)
ff1_pll<=0;
else begin
ff1_pll<=d0;
end
assign result1=ff1_pll^Done_Sig;
always@(posedge CLK1_PLL,negedge rst_pll)
if(!rst_pll)
out1<=0;
else begin
out1<=result1;
end
/********************************/
/*******************SDRAM**************/
parameter T15US = 11'd1500;
/*********************************/
reg [2:0]i;
reg [10:0]C1;
reg [4:0]C2;
reg [4:0]Used;
reg [2:0]rStart;
reg [2:0]isStart; //[2] Auto Refresh , [1] Read Action, [0] Write Action
reg isInit;
reg isBusy;
reg isDone;
always @ ( posedge CLK1 or negedge RSTn )
if( !RSTn )
begin
i <= 3'd6; // Initial SDRam at first
C1 <= 11'd0;
C2 <= 5'd0;
Used <= 5'd0;
rStart <= 3'b000;
isStart <= 3'b000;
isInit <= 1'b0;
isBusy <= 1'b1;
isDone <= 1'b0;
end
else
case( i )
0: // IDLE state
if( C1 >= T15US ) begin C1 <= 11'd0; Used <= 5'd9; rStart <= 3'b100; i <= 3'd1; end
else if( RdEN_Sig ) begin C1 <= C1 + 1'b1; Used <= 5'd8; rStart <= 3'b010;i <= 3'd3; end
else if( WrEN_Sig ) begin C1 <= C1 + 1'b1; Used <= 5'd9; rStart <= 3'b001;i <= 3'd3; end
else begin C1 <= C1 + 1'b1; end
/***************************/
1: // Auto Refresh Done , 9 clock on this step
if( C2 == Used -1 ) begin C2 <= 5'd0; i <= i + 1'b1; end
else begin isStart <= rStart; C2 <= C2 + 1'b1; end
2: // 1 clock one this step
begin isStart <= 3'd0; C1 <= C1 + 1'b1; i <= 3'd0; end
/***************************/
3: // Read and Write Done
if( C2 == Used -1) begin C2 <= 5'd0; C1 <= C1 + Used; i <= i + 1'b1; end
else begin isStart <= rStart; C2 <= C2 + 1'b1; end
/***************************************/
4: // Generate Done Signal
begin isStart <= 3'd0; isDone <= 1'b1; C1 <= C1 + 1'b1; i <= i + 1'b1; end
5:
begin isDone <= 1'b0; C1 <= C1 + 1'b1; i <= 3'd0; end
/******************************************/
6: // Initial SDRam using 21 clock
if( Init_Done_Sig ) begin isBusy <= 1'b0; isInit <= 1'b0; C1 <= C1 + 1'b1; i <= 3'd0; end
else begin isBusy <= 1'b1; isInit <= 1'b1; end
/******************************************/
endcase
/***************************************/
assign Init_Start_Sig = isInit;
assign Func_Start_Sig = isStart;
assign Done_Sig = isDone;
assign Busy_Sig = isBusy;
/***************************************/
/********************************/
reg [3:0]rData;
always @ ( posedge CLK2 or negedge RSTn )
if( !RSTn )
begin
rData <= 4'd0;
end
else
begin
rData <= Din;
end
/********************************************/
assign Dout = rData;
/********************************************/
endmodule
问题一、综合阶段报错[Synth 8-439]
现象：具体报错内容如下
[Synth 8-439] module 'PLLE2_BASE1' not found ["C:/Users/Administrator/Desktop/verilog_test/project_4/experiment15/sdram_demo3/sdram_demo3.v":52]
原因：报错信息中提示很明显，即使用了不存在的原语PLLE2_BASE1
解决：使用器件支持的原语进行例化
问题二、综合阶段报错[Synth 8-448]
现象：具体报错内容如下
[Synth 8-448] named port connection 'CLKIN1' does not exist for instance 'U1' of module 'PLLE3_ADV' ["C:/Users/Administrator/Desktop/verilog_test/project_4/experiment15/sdram_demo3/sdram_demo3.v":55]
原因：第一条报错已经很明了，即使用的PLLE3_ADV中CLKIN1端口在该原语中不存在，即例化使用的原语为其他器件支持的，当前器件不支持
第二条报错[Synth 8-6156] failed synthesizing module 'sdc_constraint' ["C:/Users/Administrator/Desktop/verilog_test/project_4/experiment15/sdram_demo3/sdram_demo3.v":1]是因为在约束文件sdc_constraint中对CLKIN1对应的端口进行了约束
约束内容如下
create_clock -period 10.000 -name clkin_pll -waveform {1.000 5.000} [get_ports CLK]
解决：首先在language templates中对应系列器件下是否支持PLLE3_ADV，如果不支持，将PLLE3_ADV修改为器件支持的原语，二是确认PLLE3_ADV的端口是否存在CLKIN1端口。经过确认，此处为PLLE3_ADV在当前xc7k480tffv中不支持，支持的为PLLE2_ADV，将PLLE3_ADV修改为PLLE2_ADV，使用对应的端口即可
问题三、在实现阶段DRC报错DRC PDRC-38
现象：具体报错内容如下：
[DRC PDRC-38] PLL_adv_ClkFrequency_clkin1: The calculated frequency value, 0.000 MHz, of the CLKIN1_PERIOD attribute on the PLLE2_ADV site PLLE2_ADV_X0Y0 (cell U1) is outside the allowed range (19.000 - 800.000 MHz). Please change the CLKIN1_PERIOD attribute value in order to be within the allowed range for this device.
原因：未对输入端口clkin1设置时钟约束，因此默认为0MHZ
解决：对设计的输入端口CLK设置时钟约束
问题四、在实现阶段DRC报错DRC PDRC-43
具体报错内容如下
[DRC PDRC-43] PLL_adv_ClkFrequency_div_no_dclk: The computed value 500.000 MHz (CLKIN1_PERIOD, net CLK_IBUF) for the VCO operating frequency of the PLLE2_ADV site PLLE2_ADV_X0Y0 (cell U1) falls outside the operating range of the PLL VCO frequency for this device (800.000 - 1600.000 MHz). The computed value is (CLKFBOUT_MULT_F * 1000 / (CLKINx_PERIOD * DIVCLK_DIVIDE)). Please adjust either the input period CLKINx_PERIOD (10.000000), multiplication factor CLKFBOUT_MULT_F (5) or the division factor DIVCLK_DIVIDE (1), in order to achieve a VCO frequency within the rated operating range for this device.
原因：约束中设置的PLL的输入时钟频率与倍频系数的乘积【Hclk*CLKFBOUT_MULT】不在【800MHZ-1600MHZ】间，约束文件中CLK周期为10ns，则频率为100MHZ，PLL例化的原语中系数CLKFBOUT_MULT(5)默认为5，因此计算出的值为500MHZ，不在要求的范围内，因此报错。
约束内容：create_clock -period 10.000 -name clkin_pll -waveform {1.000 5.000} [get_ports CLK]
解决：
方法1：修改约束中CLK的周期，使其与系数CLKFBOUT_MULT的值5相乘后在【800-1600MHZ】间
方法2：修改系数CLKFBOUT_MULT的值，可将其设置为【5-16】之间的值，此处改为10，也即CLKOUT为1000MHZ