diff --git a/Makefile b/Makefile
index 072dce4..68f21c8 100644
--- a/Makefile
+++ b/Makefile
@@ -113,7 +113,7 @@ LIB_CFLAGS   = -Wno-shadow -Wno-float-equal -Wno-inline -Wno-unused-parameter -W
 ###############################################################################
 # Linker flags
 
-LDFLAGS     += --static -lm -lc -nostartfiles  -specs=nano.specs
+LDFLAGS     += --static -lm -lc -nostartfiles  
 LDFLAGS     += -Llib
 LDFLAGS     += -T$(LDSCRIPT)
 LDFLAGS     += -Wl,-Map=$(*).map
diff --git a/project/hw_init.c b/project/hw_init.c
index b474157..60687ca 100644
--- a/project/hw_init.c
+++ b/project/hw_init.c
@@ -62,7 +62,7 @@ static void conf_subsystems(void)
 	timebase_init(15, 15);
 
 	// event and task queues
-	queues_init(15, 15);
+	queues_init(30, 30);
 
 	// initialize SBMP for ESP8266
 	dlnk_init();
diff --git a/project/main.c b/project/main.c
index 6fc5a63..f909684 100644
--- a/project/main.c
+++ b/project/main.c
@@ -20,11 +20,17 @@
 
 #include "arm_math.h"
 
+static volatile bool capture_pending = false;
+static volatile bool print_next_fft = false;
+static volatile bool capturing_silence = false;
+
+static float virt_zero_value = 2045.0f;
+
 static void poll_subsystems(void);
 
 static DotMatrix_Cfg *dmtx;
 
-#define SAMP_BUF_LEN 128
+#define SAMP_BUF_LEN 256
 
 union samp_buf_union {
 	uint32_t uints[SAMP_BUF_LEN];
@@ -44,8 +50,30 @@ void audio_capture_done(void* unused)
 
 	float *bins = samp_buf.floats;
 
+	// Convert to floats
+	for (int i = 0; i < samp_count; i++) {
+		samp_buf.floats[i] = (float)samp_buf.uints[i];
+	}
+
+	if (capturing_silence) {
+		float mean;
+		arm_mean_f32(samp_buf.floats, samp_count, &mean);
+		virt_zero_value = mean;
+		info("New zero level = %f", virt_zero_value);
+		capturing_silence = false;
+	}
+
 	for (int i = 0; i < samp_count; i++) {
-		samp_buf.floats[i] = samp_buf.uints[i] - 2045.0f;
+		samp_buf.floats[i] -= virt_zero_value;
+	}
+
+
+	if (print_next_fft) {
+		printf("--- Raw (adjusted) ---\n");
+		for(int i = 0; i < samp_count; i++) {
+			printf("%.2f, ", samp_buf.floats[i]);
+		}
+		printf("\n");
 	}
 
 	for (int i = samp_count - 1; i >= 0; i--) {
@@ -54,11 +82,19 @@ void audio_capture_done(void* unused)
 	}
 
 	const arm_cfft_instance_f32 *S;
-	S = &arm_cfft_sR_f32_len64;
+	S = &arm_cfft_sR_f32_len128;
 
 	arm_cfft_f32(S, bins, 0, true); // bit reversed FFT
 	arm_cmplx_mag_f32(bins, bins, bin_count); // get magnitude (extract real values)
 
+	if (print_next_fft) {
+		printf("--- Bins ---\n");
+		for(int i = 0; i < bin_count; i++) {
+			printf("%.2f, ", bins[i]);
+		}
+		printf("\n");
+	}
+
 	// normalize
 	dmtx_clear(dmtx);
 	float factor = (1.0f/bin_count)*0.1f;
@@ -66,7 +102,8 @@ void audio_capture_done(void* unused)
 		bins[i] *= factor;
 		bins[i+1] *= factor;
 
-		float avg = i==0 ? bins[1] : (bins[i] + bins[i+1])/2;
+		//float avg = i==0 ? bins[1] : (bins[i] + bins[i+1])/2;
+		float avg = (bins[i] + bins[i+1])/2;
 
 		for(int j = 0; j < ceilf(avg); j++) {
 			dmtx_set(dmtx, i/2, j, true);
@@ -74,25 +111,55 @@ void audio_capture_done(void* unused)
 	}
 
 	dmtx_show(dmtx);
+
+	print_next_fft = false;
+	capture_pending = false;
 }
 
 
 static void capture_audio(void *unused)
 {
 	(void)unused;
+	if (capture_pending) return;
+
+	capture_pending = true;
 
 	start_adc_dma(samp_buf.uints, SAMP_BUF_LEN/2);
 }
 
 
+static void rx_char(ComIface *iface)
+{
+	uint8_t ch;
+	while(com_rx(iface, &ch)) {
+		if (ch == 'p') {
+			info("PRINT_NEXT");
+			print_next_fft = true;
+		}
+
+		if (ch == 's') {
+			info("SILENCE");
+			capturing_silence = true;
+		}
+	}
+}
+
+
+static task_pid_t capture_task_id;
+
+
 int main(void)
 {
 	hw_init();
 
+	capturing_silence = true; // capture silence at start
+
 	banner("*** LED MATRIX DEMO ***");
 	banner_info("(c) Ondrej Hruska, 2016");
 	banner_info("Katedra mereni K338, CVUT FEL");
 
+	debug_iface->rx_callback = rx_char;
+
 	DotMatrix_Init dmtx_cfg;
 	dmtx_cfg.CS_GPIOx = GPIOA;
 	dmtx_cfg.CS_PINx = GPIO_Pin_4;
@@ -104,7 +171,13 @@ int main(void)
 
 	dmtx_intensity(dmtx, 7);
 
-	add_periodic_task(capture_audio, NULL, 10, false);
+	for(int i = 0; i < 16; i++) {
+		dmtx_set(dmtx, i, 0, 1);
+		dmtx_show(dmtx);
+		delay_ms(25);
+	}
+
+	capture_task_id = add_periodic_task(capture_audio, NULL, 10, false);
 
 	ms_time_t last;
 	while (1) {