homescreen/src/mastervolume.h

FM configuration improvements

Changes include:
- Add command-line option for selecting FM band plan.  The default
  band plan is US / Canada.
- Add command-line options for setting FM scanning valid SNR and RSSI
  thresholds to allow tweaking sensitivity in poor radio environments.
- Increased seeking scan timeout to 3 seconds, which seems to improve
  behavior in poor radio environments where powerful stations may be
  far apart.
- Removed explicit setting of FM_SOFTMUTE_SNR_LIMITS, as it seemed
  like it might be resulting in odd muting behavior when scanning.
- Changed initial FM frequency if not specified to the minimum of the
  band plan.

Signed-off-by: Scott Murray <scott.murray@konsulko.com>

diff --git a/si46xx.h b/si46xx.h
index 172ea8b..c32fca4 100644
--- a/si46xx.h
+++ b/si46xx.h
@@ -83,6 +83,7 @@
 #define SI46XX_PIN_CONFIG_ENABLE 0x0800
 #define SI46XX_FM_SEEK_BAND_BOTTOM 0x3100
 #define SI46XX_FM_SEEK_BAND_TOP 0x3101
+#define SI46XX_FM_SEEK_FREQUENCY_SPACING 0x3102
 #define SI46XX_FM_VALID_MAX_TUNE_ERROR 0x3200
 #define SI46XX_FM_VALID_RSSI_TIME 0x3201
 #define SI46XX_FM_VALID_RSSI_THRESHOLD 0x3202
@@ -150,7 +151,7 @@
 #define MAX_SERVICES 32
 #define MAX_COMPONENTS 15
 
-#define TIMEOUT_SEEK	2000	/* mS = 2S */
+#define TIMEOUT_SEEK	3000	/* mS = 3S */
 #define TIMEOUT_TUNE	500	/* mS = .5S */
 
 struct dab_service_t{
diff --git a/si_ctl.c b/si_ctl.c
index 59dfaf2..f168218 100644
--- a/si_ctl.c
+++ b/si_ctl.c
@@ -101,6 +101,26 @@ uint32_t frequency_list_ch[] = {	CHAN_12A,
 					CHAN_9D,
 					CHAN_8B};
 
+// Structure to describe FM band plans, all values in Hz.
+typedef struct {
+	char *name;
+	uint32_t min;
+	uint32_t max;
+	uint32_t step;
+} fm_band_plan_t;
+
+static fm_band_plan_t known_fm_band_plans[5] = {
+	{ .name = "US", .min = 87900000, .max = 107900000, .step = 200000 },
+	{ .name = "JP", .min = 76000000, .max = 95000000, .step = 100000 },
+	{ .name = "EU", .min = 87500000, .max = 108000000, .step = 50000 },
+	{ .name = "ITU-1", .min = 87500000, .max = 108000000, .step = 50000 },
+	{ .name = "ITU-2", .min = 87900000, .max = 107900000, .step = 50000 }
+};
+
+static unsigned int fm_band_plan;
+static int fm_snr_threshold = 128;
+static int fm_rssi_threshold = 128;
+
 int init_am(int offset)
 {
 	int ret;
@@ -160,12 +180,32 @@ int init_fm(int offset)
 	 * enable I2S output
 	 */
 	si46xx_set_property(SI46XX_PIN_CONFIG_ENABLE, 0x0003);
-	//si46xx_set_property(SI46XX_FM_VALID_RSSI_THRESHOLD,0x0000);
-	//si46xx_set_property(SI46XX_FM_VALID_SNR_THRESHOLD,0x0000);
-	si46xx_set_property(SI46XX_FM_SOFTMUTE_SNR_LIMITS, 0x0000); // set the SNR limits for soft mute attenuation
+	//si46xx_set_property(SI46XX_FM_SOFTMUTE_SNR_LIMITS, 0x0000); // set the SNR limits for soft mute attenuation
 	si46xx_set_property(SI46XX_FM_TUNE_FE_CFG, 0x0000); // front end switch open
-	si46xx_set_property(SI46XX_FM_SEEK_BAND_BOTTOM, 88000 / 10);
-	si46xx_set_property(SI46XX_FM_SEEK_BAND_TOP, 108000 / 10);
+
+	//si46xx_set_property(SI46XX_FM_SEEK_BAND_BOTTOM, 88000 / 10);
+	//si46xx_set_property(SI46XX_FM_SEEK_BAND_TOP, 108000 / 10);
+	if (verbose)
+		fprintf(stderr, "Using FM Bandplan: %s\n", known_fm_band_plans[fm_band_plan].name);
+	si46xx_set_property(SI46XX_FM_SEEK_BAND_BOTTOM, known_fm_band_plans[fm_band_plan].min / 10000);
+	si46xx_set_property(SI46XX_FM_SEEK_BAND_TOP, known_fm_band_plans[fm_band_plan].max / 10000);
+	if (verbose)
+		fprintf(stderr, "Using FM band: %d - %d, %d spacing\n",
+			known_fm_band_plans[fm_band_plan].min / 10000,
+			known_fm_band_plans[fm_band_plan].max / 10000,
+			known_fm_band_plans[fm_band_plan].step / 10000);
+	si46xx_set_property(SI46XX_FM_SEEK_FREQUENCY_SPACING, known_fm_band_plans[fm_band_plan].step / 10000);
+	if (fm_snr_threshold != 128) {
+		if (verbose)
+			fprintf(stderr, "Setting FM valid SNR threshold to %d dB\n", fm_snr_threshold);
+		si46xx_set_property(SI46XX_FM_VALID_SNR_THRESHOLD, fm_snr_threshold);
+	}
+	if (fm_rssi_threshold != 128) {
+		if (verbose)
+			fprintf(stderr, "Setting FM valid RSSI threshold to %d dB\n", fm_rssi_threshold);
+		si46xx_set_property(SI46XX_FM_VALID_RSSI_THRESHOLD, fm_rssi_threshold);
+	}
+
 	/*
 	 * rate
 	 */
@@ -190,6 +230,7 @@ int init_fm(int offset)
 
 	return 0;
 }
+
 int init_dab(int offset)
 {
 	int ret;
@@ -245,6 +286,10 @@ int output_help(char *prog_name)
 	printf("  -l up|down     FM/AM seek next station\n");
 	printf("  -d             FM/AM RSQ status\n");
 	printf("  -m             FM rds status\n");
+	printf("Common FM:\n");
+	printf("  -p bandplan    FM bandplan (us, jp, eu, itu-1, itu-2\n");
+	printf("  -t SNR         FM scan valid SNR threshold (-127 to 127 dB)\n");
+	printf("  -u RSSI        FM scan valid RSSI threshold (-127 to 127 dBuV)\n");
 	printf("DAB only:\n");
 	printf("  -e             dab status\n");
 	printf("  -f service     start service of dab service list\n");
@@ -354,6 +399,7 @@ int main(int argc, char **argv)
 	int offset = - 1;
 	int mode;
 	int tmp;
+	unsigned int i;
 	struct dab_digrad_status_t dab_digrad_status;
 	bool init = false;
 	bool seek_up = false;
@@ -374,7 +420,7 @@ int main(int argc, char **argv)
 
 	optind = 0;
 	while (optind < argc) {
-		if ((c = getopt(argc, argv, "a:b:c:def:ghi:j:k:l:mnosv")) != -1) {
+		if ((c = getopt(argc, argv, "a:b:c:def:ghi:j:k:l:mnop:st:u:v")) != -1) {
 			switch(c){
 			/* init */
 			case 'a':
@@ -422,6 +468,31 @@ int main(int argc, char **argv)
 			case 'c':
 				frequency = atoi(optarg);
 				break;
+			/* FM */
+			case 'p':
+				for(i = 0;
+				    i < sizeof(known_fm_band_plans) / sizeof(fm_band_plan_t);
+				    i++) {
+					if(!strcasecmp(optarg, known_fm_band_plans[i].name)) {
+						fm_band_plan = i;
+						break;
+					}
+				}
+				if(i >= (sizeof(known_fm_band_plans) / sizeof(fm_band_plan_t))) {
+					printf("Invalid mode: %s\n", optarg);
+					return -EINVAL;
+				}
+				break;
+			case 't':
+				fm_snr_threshold = atoi(optarg);
+				if(fm_snr_threshold < -128 || fm_snr_threshold > 127)
+					fm_snr_threshold = 128; // use firmware default
+				break;
+			case 'u':
+				fm_rssi_threshold = atoi(optarg);
+				if(fm_rssi_threshold < -128 || fm_rssi_threshold > 127)
+					fm_rssi_threshold = 128; // use firmware default
+				break;
 			/* DAB stuff. TODO: rework */
 			case 'e':
 				si46xx_dab_digrad_status(&dab_digrad_status);
@@ -473,7 +544,7 @@ int main(int argc, char **argv)
 			case SI46XX_MODE_FM:
 				ret = init_fm(offset);
 				if (frequency < 0)
-					frequency = 105500;
+					frequency = known_fm_band_plans[fm_band_plan].min / 1000;
 			break;
 			case SI46XX_MODE_AM:
 				ret = init_am(offset);