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Added dynamic phase shift information into output and output file comments #175

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Added dynamic phase shift information into output and output file comments #175

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541e398
ecppll: Fixed inconsistent tab/space usage.
rowanG077 Jul 28, 2021
71a3f9a
ecppll: Added documentation and calculated how much a dynamic phase s…
rowanG077 Jul 28, 2021
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154 changes: 108 additions & 46 deletions libtrellis/tools/ecppll.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,8 @@ struct secondary_params{

float freq;
float phase;
float phase_vco_step;
float phase_div_step;
};

struct pll_params{
Expand All @@ -62,6 +64,10 @@ struct pll_params{
int feedback_div;
int output_div;
int primary_cphase;
int primary_fphase;
float primary_phase_vco_step;
float primary_phase_div_step;

string clkin_name;
string clkout0_name;
int dynamic;
Expand All @@ -85,6 +91,8 @@ struct pll_params{
}
};

float calc_vco_phase_step(int fphase, int div);
float calc_div_phase_step(int cphase, int div);
void calc_pll_params(pll_params &params, float input, float output);
void calc_pll_params_highres(pll_params &params, float input, float output);
void generate_secondary_output(pll_params &params, int channel, string name, float frequency, float phase);
Expand Down Expand Up @@ -245,22 +253,38 @@ int main(int argc, char** argv){
cout << "Feedback divisor: " << params.feedback_div << endl;
cout << "clkout0 divisor: " << params.output_div << "" << endl;
cout << "clkout0 frequency: " << params.fout << " MHz" << endl;
if(params.dynamic){
cout << "clkout0 vco step: " << params.primary_phase_vco_step << " degrees" << endl;
cout << "clkout0 div step: " << params.primary_phase_div_step << " degrees" << endl;
}
if(params.secondary[0].enabled){
cout << "clkout1 divisor: " << params.secondary[0].div << endl;
cout << "clkout1 frequency: " << params.secondary[0].freq << " MHz" << endl;
cout << "clkout1 phase shift: " << params.secondary[0].phase << " degrees" << endl;
if(params.dynamic){
cout << "clkout1 vco step: " << params.secondary[0].phase_vco_step << " degrees" << endl;
cout << "clkout1 div step: " << params.secondary[0].phase_div_step << " degrees" << endl;
}
}
if(params.secondary[1].enabled){
cout << "clkout2 divisor: " << params.secondary[1].div << endl;
cout << "clkout2 frequency: " << params.secondary[1].freq << " MHz" << endl;
cout << "clkout2 phase shift: " << params.secondary[1].phase << " degrees" << endl;
if(params.dynamic){
cout << "clkout2 vco step: " << params.secondary[1].phase_vco_step << " degrees" << endl;
cout << "clkout2 div step: " << params.secondary[1].phase_div_step << " degrees" << endl;
}
}
if(params.secondary[2].enabled){
cout << "clkout3 divisor: " << params.secondary[2].div << endl;
cout << "clkout3 frequency: " << params.secondary[2].freq << " MHz" << endl;
cout << "clkout3 phase shift: " << params.secondary[2].phase << " degrees" << endl;
if(params.dynamic){
cout << "clkout3 vco step: " << params.secondary[2].phase_vco_step << " degrees" << endl;
cout << "clkout3 div step: " << params.secondary[2].phase_div_step << " degrees" << endl;
}
}
cout << "VCO frequency: " << params.fvco << endl;
cout << "VCO frequency: " << params.fvco << " Mhz" << endl;
if(vm.count("file")){
ofstream f;
f.open(vm["file"].as<string>().c_str());
Expand All @@ -269,6 +293,14 @@ int main(int argc, char** argv){
}
}

float calc_vco_phase_step(int fphase, int div){
return (360.f * (float)fphase) / (8.f * (float)div);
}

float calc_div_phase_step(int cphase, int div){
return (360.f * ((float)cphase - (float)div)) / (1.f + (float)div);
}

void calc_pll_params(pll_params &params, float input, float output){
float error = std::numeric_limits<float>::max();
for(int input_div=1;input_div <= 128; input_div++){
Expand All @@ -278,24 +310,29 @@ void calc_pll_params(pll_params &params, float input, float output){
continue;
for(int feedback_div=1;feedback_div <= 80; feedback_div++){
for(int output_div=1;output_div <= 128; output_div++){
float fvco = fpfd * (float)feedback_div * (float) output_div;

if(fvco < VCO_MIN || fvco > VCO_MAX)
continue;

float fout = fvco / (float) output_div;
if(fabsf(fout - output) < error ||
(fabsf(fout-output) == error && fabsf(fvco - 600) < fabsf(params.fvco - 600))){
error = fabsf(fout-output);
params.refclk_div = input_div;
params.feedback_div = feedback_div;
params.output_div = output_div;
params.fout = fout;
params.fvco = fvco;
// shift the primary by 180 degrees. Lattice seems to do this
float ns_phase = 1/(fout * 1e6) * 0.5;
params.primary_cphase = ns_phase * (fvco * 1e6);
}
float fvco = fpfd * (float)feedback_div * (float) output_div;

if(fvco < VCO_MIN || fvco > VCO_MAX)
continue;

float fout = fvco / (float) output_div;
if(fabsf(fout - output) < error ||
(fabsf(fout-output) == error && fabsf(fvco - 600) < fabsf(params.fvco - 600))){
error = fabsf(fout-output);
params.refclk_div = input_div;
params.feedback_div = feedback_div;
params.output_div = output_div;
params.fout = fout;
params.fvco = fvco;
// shift the primary by 180 degrees. Lattice seems to do this
float ns_phase = 1/(fout * 1e6) * 0.5;
float phase_count = ns_phase * (fvco * 1e6);
params.primary_cphase = phase_count;
int cphase = (int) phase_count;
params.primary_fphase = (int) ((phase_count - cphase) * 8);
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This is the same calculation as done for secondary clocks is this correct?

params.primary_phase_vco_step = calc_vco_phase_step(params.primary_fphase, params.output_div);
params.primary_phase_div_step = calc_div_phase_step(params.primary_cphase, params.output_div);
}
}
}
}
Expand All @@ -310,29 +347,38 @@ void calc_pll_params_highres(pll_params &params, float input, float output){
continue;
for(int feedback_div=1;feedback_div <= 80; feedback_div++){
for(int output_div=1;output_div <= 128; output_div++){
float fvco = fpfd * (float)feedback_div * (float) output_div;

if(fvco < VCO_MIN || fvco > VCO_MAX)
continue;
float ffeedback = fvco / (float) output_div;
if(ffeedback < OUTPUT_MIN || ffeedback > OUTPUT_MAX)
continue;
for(int secondary_div = 1; secondary_div <= 128; secondary_div++){
float fout = fvco / (float) secondary_div;
if(fabsf(fout - output) < error ||
(fabsf(fout-output) == error && fabsf(fvco - 600) < fabsf(params.fvco - 600))){
error = fabsf(fout-output);
params.mode = pll_mode::HIGHRES;
params.refclk_div = input_div;
params.feedback_div = feedback_div;
params.output_div = output_div;
params.secondary[0].div = secondary_div;
params.secondary[0].enabled = true;
params.secondary[0].freq = fout;
params.fout = fout;
params.fvco = fvco;
}
}
float fvco = fpfd * (float)feedback_div * (float) output_div;

if(fvco < VCO_MIN || fvco > VCO_MAX)
continue;
float ffeedback = fvco / (float) output_div;
if(ffeedback < OUTPUT_MIN || ffeedback > OUTPUT_MAX)
continue;
for(int secondary_div = 1; secondary_div <= 128; secondary_div++){
float fout = fvco / (float) secondary_div;
if(fabsf(fout - output) < error ||
(fabsf(fout-output) == error && fabsf(fvco - 600) < fabsf(params.fvco - 600))){
error = fabsf(fout-output);
params.mode = pll_mode::HIGHRES;
params.refclk_div = input_div;
params.feedback_div = feedback_div;
params.output_div = output_div;
params.secondary[0].div = secondary_div;
params.secondary[0].enabled = true;
params.secondary[0].freq = fout;
params.fout = fout;
params.fvco = fvco;

// Is this correct for highres mode?
float ns_phase = 1/(fout * 1e6) * 0.5;
float phase_count = ns_phase * (fvco * 1e6);
params.primary_cphase = phase_count;
int cphase = (int) phase_count;
params.primary_fphase = (int) ((phase_count - cphase) * 8);
params.primary_phase_vco_step = calc_vco_phase_step(params.primary_fphase, params.output_div);
params.primary_phase_div_step = calc_div_phase_step(params.primary_cphase, params.output_div);
}
}
}
}
}
Expand All @@ -359,6 +405,8 @@ void generate_secondary_output(pll_params &params, int channel, string name, flo
params.secondary[channel].cphase = cphase + params.primary_cphase;
params.secondary[channel].fphase = fphase;
params.secondary[channel].name = name;
params.secondary[channel].phase_vco_step = calc_vco_phase_step(fphase, div);
params.secondary[channel].phase_div_step = calc_div_phase_step(params.secondary[channel].cphase, div);
}

void write_pll_config(const pll_params & params, const string &name, ofstream& file)
Expand All @@ -376,8 +424,22 @@ void write_pll_config(const pll_params & params, const string &name, ofstream& f
{
file << " input [1:0] phasesel, // clkout[] index affected by dynamic phase shift (except clkfb), 5 ns min before apply\n";
file << " input phasedir, // 0:delayed (lagging), 1:advence (leading), 5 ns min before apply\n";
file << " input phasestep, // 45 deg step, high for 5 ns min, falling edge = apply\n";
file << " input phaseloadreg, // high for 10 ns min, falling edge = apply\n";
file << " // high for 5 ns min, falling edge = apply\n";
file << " // " << params.primary_phase_vco_step << " deg step for " << params.clkout0_name << "\n";
for (int i = 0; i < 3; ++i){
if(params.secondary[i].enabled){
file << " // " << params.secondary[i].phase_vco_step << " deg step for " << params.secondary[i].name << "\n";
}
}
file << " input phasestep,\n";
file << " // high for 10 ns min, falling edge = apply\n";
file << " // " << params.primary_phase_div_step << " deg step for " << params.clkout0_name << "\n";
for (int i = 0; i < 3; ++i){
if(params.secondary[i].enabled){
file << " // " << params.secondary[i].phase_div_step << " deg step for " << params.secondary[i].name << "\n";
}
}
file << " input phaseloadreg,\n";
}
file << " input " << params.clkin_name << ", // " << params.clkin_frequency << " MHz, 0 deg\n";
file << " output " << params.clkout0_name << ", // " << params.fout << " MHz, 0 deg\n";
Expand Down Expand Up @@ -422,7 +484,7 @@ void write_pll_config(const pll_params & params, const string &name, ofstream& f
file << " .CLKOP_ENABLE(\"ENABLED\"),\n";
file << " .CLKOP_DIV(" << params.output_div << "),\n";
file << " .CLKOP_CPHASE(" << params.primary_cphase << "),\n";
file << " .CLKOP_FPHASE(0),\n";
file << " .CLKOP_FPHASE(" << params.primary_fphase << "),\n";
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@rowanG077 rowanG077 Jul 28, 2021 •
edited
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Why was 0 used here? The calculated fphase is not always 0.

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Thanks, I'll need to take some time to look into this as it's been a good while since I touched the ECP5 PLLs. I will keep this on my list though.

if(params.secondary[0].enabled){
file << " .CLKOS_ENABLE(\"ENABLED\"),\n";
file << " .CLKOS_DIV(" << params.secondary[0].div << "),\n";
Expand Down Expand Up @@ -504,6 +566,6 @@ void write_pll_config(const pll_params & params, const string &name, ofstream& f
file << " .PLLWAKESYNC(1'b0),\n";
file << " .ENCLKOP(1'b0),\n";
file << " .LOCK(locked)\n";
file << " );\n";
file << " );\n";
file << "endmodule\n";
}