Merge pull request #245 from SmallRoomLabs/iteratePLL

icepll: Add iteration over list of frequencies for best solution

1 files changed, 153 insertions, 54 deletions

diff --git a/icepll/icepll.cc b/icepll/icepll.cc
index f9ebecf..a2db72f 100644
--- a/icepll/icepll.cc
+++ b/icepll/icepll.cc
@@ -51,6 +51,14 @@ void help(const char *cmd)
 	printf("    -S\n");
 	printf("        Disable SIMPLE feedback path mode\n");
 	printf("\n");
+	printf("    -b\n");
+	printf("        Find best input frequency for desired PLL Output frequency\n");
+	printf("        using the normally stocked oscillators at Mouser\n");
+	printf("\n");
+	printf("    -B <filename>\n");
+	printf("        Find best input frequency for desired PLL Output frequency\n");
+	printf("        using frequencies read from <filename>\n");
+	printf("\n");
 	printf("    -f <filename>\n");
 	printf("        Save PLL configuration as Verilog to file\n");
 	printf("        If <filename> is - then the Verilog is written to stdout.\n");
@@ -67,6 +75,119 @@ void help(const char *cmd)
 	exit(1);
 }
 
+bool analyze(
+		bool simple_feedback, double f_pllin, double f_pllout,
+		double *best_fout, int *best_divr, int *best_divf, int *best_divq
+		) 
+{
+	bool found_something = false;
+	*best_fout = 0;
+	*best_divr = 0;
+	*best_divf = 0;
+	*best_divq = 0;
+
+	int divf_max = simple_feedback ? 127 : 63;
+	// The documentation in the iCE40 PLL Usage Guide incorrectly lists the
+	// maximum value of DIVF as 63, when it is only limited to 63 when using
+	// feedback modes other that SIMPLE.
+
+	if (f_pllin < 10 || f_pllin > 133) {
+		fprintf(stderr, "Error: PLL input frequency %.3f MHz is outside range 10 MHz - 133 MHz!\n", f_pllin);
+		exit(1);
+	}
+
+	if (f_pllout < 16 || f_pllout > 275) {
+		fprintf(stderr, "Error: PLL output frequency %.3f MHz is outside range 16 MHz - 275 MHz!\n", f_pllout);
+		exit(1);
+	}
+
+	for (int divr = 0; divr <= 15; divr++)
+	{
+		double f_pfd = f_pllin / (divr + 1);
+		if (f_pfd < 10 || f_pfd > 133) continue;
+
+		for (int divf = 0; divf <= divf_max; divf++)
+		{
+			if (simple_feedback)
+			{
+				double f_vco = f_pfd * (divf + 1);
+				if (f_vco < 533 || f_vco > 1066) continue;
+
+				for (int divq = 1; divq <= 6; divq++)
+				{
+					double fout = f_vco * exp2(-divq);
+
+					if (fabs(fout - f_pllout) < fabs(*best_fout - f_pllout) || !found_something) {
+						*best_fout = fout;
+						*best_divr = divr;
+						*best_divf = divf;
+						*best_divq = divq;
+						found_something = true;
+					}
+				}
+			}
+			else
+			{
+				for (int divq = 1; divq <= 6; divq++)
+				{
+					double f_vco = f_pfd * (divf + 1) * exp2(divq);
+					if (f_vco < 533 || f_vco > 1066) continue;
+
+					double fout = f_vco * exp2(-divq);
+
+					if (fabs(fout - f_pllout) < fabs(*best_fout - f_pllout) || !found_something) {
+						*best_fout = fout;
+						*best_divr = divr;
+						*best_divf = divf;
+						*best_divq = divq;
+						found_something = true;
+					}
+				}
+			}
+		}
+	}
+
+	return found_something;
+}
+
+	// Table of frequencies to test in "best" mode defaults to ABRACOM Crystal 
+	// oscillators "Normally stocked" at Mouser
+	double freq_table[100] = 
+	{
+		10, 11.0592, 11.2896, 11.7846, 12, 12.288, 12.352, 12.5, 13, 13.5, 13.6, 14.31818, 14.7456, 15, 16, 16.384, 17.2032, 18.432, 19.2, 19.44, 19.6608, 
+		20, 24, 24.576, 25, 26, 27, 27.12, 28.63636, 28.9, 29.4912, 
+		30, 32, 32.768, 33, 33.206, 33.333, 35.328, 36, 37.03, 37.4, 38.4, 38.88, 
+		40, 40.95, 40.97, 44, 44.736, 48, 
+		50, 54, 57.692, 
+		60, 64, 65, 66, 66.666, 68, 
+		70, 72, 75, 76.8, 
+		80, 80.92, 
+		92.16, 96, 98.304, 
+		100, 104, 106.25, 108, 
+		114.285, 
+		120, 122.88, 125,
+		0
+	};
+
+void readfreqfile(const char *filename) {
+	FILE *f;
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		fprintf(stderr, "Error: Can't open file %s!\n",filename);
+		exit(1);
+	}
+
+	// Clear and overwrite the default values in the table
+	memset(freq_table, 0, sizeof(freq_table));
+	int i = 0;
+	double freq=0;
+	while((i < sizeof(freq_table)/sizeof(double)) && (fscanf(f, "%lf", &freq) > 0))
+	{
+		freq_table[i++] = freq;
+	}
+	fclose(f);
+}
+
 int main(int argc, char **argv)
 {
 #ifdef __EMSCRIPTEN__
@@ -88,10 +209,12 @@ int main(int argc, char **argv)
 	bool file_stdout = false;
 	const char* module_name = NULL;
 	bool save_as_module = false;
+	bool best_mode = false;
+	const char* freqfile = NULL;
 	bool quiet = false;
 
 	int opt;
-	while ((opt = getopt(argc, argv, "i:o:Smf:n:q")) != -1)
+	while ((opt = getopt(argc, argv, "i:o:Smf:n:bB:q")) != -1)
 	{
 		switch (opt)
 		{
@@ -113,6 +236,13 @@ int main(int argc, char **argv)
 		case 'n':
 			module_name = optarg;
 			break;
+		case 'b':
+			best_mode = true;
+			break;
+		case 'B':
+			best_mode = true;
+			freqfile = optarg;
+			break;
 		case 'q':
 			quiet = true;
 			break;
@@ -137,68 +267,37 @@ int main(int argc, char **argv)
 		quiet = true;
 	}
 
+	if (freqfile) {
+		readfreqfile(freqfile);
+	}
+
 	bool found_something = false;
 	double best_fout = 0;
 	int best_divr = 0;
 	int best_divf = 0;
 	int best_divq = 0;
 
-	// The documentation in the iCE40 PLL Usage Guide incorrectly lists the
-	// maximum value of DIVF as 63, when it is only limited to 63 when using
-	// feedback modes other that SIMPLE.
-	int divf_max = simple_feedback ? 127 : 63;
-
-	if (f_pllin < 10 || f_pllin > 133) {
-		fprintf(stderr, "Error: PLL input frequency %.3f MHz is outside range 10 MHz - 133 MHz!\n", f_pllin);
-		exit(1);
-	}
-
-	if (f_pllout < 16 || f_pllout > 275) {
-		fprintf(stderr, "Error: PLL output frequency %.3f MHz is outside range 16 MHz - 275 MHz!\n", f_pllout);
-		exit(1);
-	}
-
-	for (int divr = 0; divr <= 15; divr++)
-	{
-		double f_pfd = f_pllin / (divr + 1);
-		if (f_pfd < 10 || f_pfd > 133) continue;
-
-		for (int divf = 0; divf <= divf_max; divf++)
+	if (!best_mode) {
+		// Use only specified input frequency
+		found_something = analyze(simple_feedback, f_pllin, f_pllout, &best_fout, &best_divr, &best_divf, &best_divq);
+	} else {
+		// Iterate over all standard crystal frequencies and select the best
+		for (int i = 0; freq_table[i]>0.0 ; i++) 
 		{
-			if (simple_feedback)
-			{
-				double f_vco = f_pfd * (divf + 1);
-				if (f_vco < 533 || f_vco > 1066) continue;
-
-				for (int divq = 1; divq <= 6; divq++)
-				{
-					double fout = f_vco * exp2(-divq);
-
-					if (fabs(fout - f_pllout) < fabs(best_fout - f_pllout) || !found_something) {
-						best_fout = fout;
-						best_divr = divr;
-						best_divf = divf;
-						best_divq = divq;
-						found_something = true;
-					}
-				}
-			}
-			else
+			double fout = 0;
+			int divr = 0;
+			int divf = 0;
+			int divq = 0;
+			if (analyze(simple_feedback, freq_table[i], f_pllout, &fout, &divr, &divf, &divq))
 			{
-				for (int divq = 1; divq <= 6; divq++)
+				found_something = true;
+				if (abs(fout - f_pllout) < abs(best_fout - f_pllout)) 
 				{
-					double f_vco = f_pfd * (divf + 1) * exp2(divq);
-					if (f_vco < 533 || f_vco > 1066) continue;
-
-					double fout = f_vco * exp2(-divq);
-
-					if (fabs(fout - f_pllout) < fabs(best_fout - f_pllout) || !found_something) {
-						best_fout = fout;
-						best_divr = divr;
-						best_divf = divf;
-						best_divq = divq;
-						found_something = true;
-					}
+					f_pllin = freq_table[i];
+					best_fout = fout;
+					best_divr = divr;
+					best_divf = divf;
+					best_divq = divq;
 				}
 			}
 		}