From edd2fdd023fffab8c816349a4ddf4c7bb5d79661 Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Sun, 17 Jun 2012 18:20:01 +0200
Subject: [PATCH 1/4] Audio: first draft

---
 .../arduino/sam/libraries/Audio/Audio.cpp     | 104 ++++++++++++++++++
 hardware/arduino/sam/libraries/Audio/Audio.h  |  24 ++++
 .../arduino/sam/libraries/Audio/keywords.txt  |   0
 3 files changed, 128 insertions(+)
 create mode 100644 hardware/arduino/sam/libraries/Audio/Audio.cpp
 create mode 100644 hardware/arduino/sam/libraries/Audio/Audio.h
 create mode 100644 hardware/arduino/sam/libraries/Audio/keywords.txt

diff --git a/hardware/arduino/sam/libraries/Audio/Audio.cpp b/hardware/arduino/sam/libraries/Audio/Audio.cpp
new file mode 100644
index 000000000..23051045d
--- /dev/null
+++ b/hardware/arduino/sam/libraries/Audio/Audio.cpp
@@ -0,0 +1,104 @@
+
+#include "Audio.h"
+
+static void TC_SetRA(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RA = v;
+}
+
+static void TC_SetRB(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RB = v;
+}
+
+static void TC_SetRC(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RC = v;
+}
+
+void AudioClass::begin(uint32_t sampleRate) {
+	// Enable clock for DAC
+	pmc_enable_periph_clk(dacId);
+
+	dacc_reset(dac);
+
+	// Set transfer mode to double word
+	dacc_set_transfer_mode(dac, 1);
+
+	// Power save:
+	// sleep mode  - 0 (disabled)
+	// fast wakeup - 0 (disabled)
+	dacc_set_power_save(dac, 0, 0);
+
+	// ADC refresh/startup timings:
+	// refresh        - 0x08 (1024*8 dacc clocks)
+	// max speed mode -    0 (disabled)
+	// startup time   - 0x10 (1024 dacc clocks)
+	dacc_set_timing(dac, 0x08, 0, DACC_MR_STARTUP_1024);
+
+	// Flexible channel selection with tags
+	dacc_enable_flexible_selection(dac);
+
+	// Set up analog current
+	dacc_set_analog_control(dac,
+			DACC_ACR_IBCTLCH0(0x02) |
+			DACC_ACR_IBCTLCH1(0x02) |
+			DACC_ACR_IBCTLDACCORE(0x01));
+
+	// Enable output channels
+	dacc_enable_channel(dac, 0);
+	dacc_enable_channel(dac, 1);
+
+
+	// Configure Timer Counter to trigger DAC
+	// --------------------------------------
+	pmc_enable_periph_clk(ID_TC0);
+	TC_Configure(TC0, 1,
+		TC_CMR_TCCLKS_TIMER_CLOCK2 |
+		TC_CMR_WAVE |         // Waveform mode
+		TC_CMR_WAVSEL_UP_RC | // Counter running up and reset when equals to RC
+		TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR);
+	const uint32_t TC = VARIANT_MCK / 8 / sampleRate;
+	TC_SetRA(TC0, 1, TC / 2);
+	TC_SetRC(TC0, 1, TC);
+	TC_Start(TC0, 1);
+
+	// Configure clock source for DAC (1 = TC0 Output Chan. 1)
+	dacc_set_trigger(dac, 1);
+}
+
+void AudioClass::end() {
+	TC_Stop(TC0, 1);
+	dacc_disable_channel(dac, 0);
+	dacc_disable_channel(dac, 1);
+}
+
+size_t AudioClass::write(const uint8_t *buffer, size_t size) {
+
+	// Try the first PDC buffer
+	if ((dac->DACC_TCR == 0) && (dac->DACC_TNCR == 0)) {
+		dac->DACC_TPR = (uint32_t) buffer;
+		dac->DACC_TCR = size;
+		dac->DACC_PTCR = DACC_PTCR_TXTEN;
+		return size;
+	}
+
+	// Try the second PDC buffer
+	if (dac->DACC_TNCR == 0) {
+		dac->DACC_TNPR = (uint32_t) buffer;
+		dac->DACC_TNCR = size;
+		dac->DACC_PTCR = DACC_PTCR_TXTEN;
+		return size;
+	}
+
+	// PDC buffers full, try again later...
+	return 0;
+}
+
+AudioClass Audio(DACC_INTERFACE, DACC_INTERFACE_ID);
+
+//void DACC_IrqHandler(void) {
+//	uint32_t sr = DACC_INTERFACE->DACC_ISR;
+//
+//	if (sr & DACC_ISR_ENDTX) {
+//		/* End of transmission */
+//		Audio.write(wBuffer, SAMPLES);
+//	}
+//}
diff --git a/hardware/arduino/sam/libraries/Audio/Audio.h b/hardware/arduino/sam/libraries/Audio/Audio.h
new file mode 100644
index 000000000..aae6f1363
--- /dev/null
+++ b/hardware/arduino/sam/libraries/Audio/Audio.h
@@ -0,0 +1,24 @@
+#ifndef AUDIO_H
+#define AUDIO_H
+
+#include "Arduino.h"
+//#include <inttypes.h>
+#include "Print.h"
+
+class AudioClass : public Print {
+public:
+	AudioClass(Dacc *_dac, uint32_t _dacId) : dac(_dac), dacId(_dacId) { };
+	void begin(uint32_t sampleRate);
+	void end();
+
+	virtual size_t write(uint8_t c) { write(&c, 1); };
+	virtual size_t write(const uint8_t *buffer, size_t size);
+
+private:
+	Dacc *dac;
+	uint32_t dacId;
+};
+
+extern AudioClass Audio;
+
+#endif
diff --git a/hardware/arduino/sam/libraries/Audio/keywords.txt b/hardware/arduino/sam/libraries/Audio/keywords.txt
new file mode 100644
index 000000000..e69de29bb

From 6695518cffb527ec58417aceb8b131cb98da3e5e Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Mon, 18 Jun 2012 01:53:53 +0200
Subject: [PATCH 2/4] Audio library: improved DMA transfers. Stereo output.

---
 .../arduino/sam/libraries/Audio/Audio.cpp     | 56 +++++++++++++++----
 hardware/arduino/sam/libraries/Audio/Audio.h  | 24 +++++++-
 2 files changed, 67 insertions(+), 13 deletions(-)

diff --git a/hardware/arduino/sam/libraries/Audio/Audio.cpp b/hardware/arduino/sam/libraries/Audio/Audio.cpp
index 23051045d..0831d1876 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.cpp
+++ b/hardware/arduino/sam/libraries/Audio/Audio.cpp
@@ -1,3 +1,12 @@
+/*
+ * Copyright (c) 2012 by Cristian Maglie <c.maglie@bug.st>
+ * Audio library for Arduino Due.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
 
 #include "Audio.h"
 
@@ -49,19 +58,31 @@ void AudioClass::begin(uint32_t sampleRate) {
 
 	// Configure Timer Counter to trigger DAC
 	// --------------------------------------
-	pmc_enable_periph_clk(ID_TC0);
+	pmc_enable_periph_clk(ID_TC1);
 	TC_Configure(TC0, 1,
-		TC_CMR_TCCLKS_TIMER_CLOCK2 |
-		TC_CMR_WAVE |         // Waveform mode
-		TC_CMR_WAVSEL_UP_RC | // Counter running up and reset when equals to RC
+		TC_CMR_TCCLKS_TIMER_CLOCK2 |  // Clock at MCR/8
+		TC_CMR_WAVE |                 // Waveform mode
+		TC_CMR_WAVSEL_UP_RC |         // Counter running up and reset when equals to RC
 		TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR);
 	const uint32_t TC = VARIANT_MCK / 8 / sampleRate;
 	TC_SetRA(TC0, 1, TC / 2);
 	TC_SetRC(TC0, 1, TC);
 	TC_Start(TC0, 1);
 
-	// Configure clock source for DAC (1 = TC0 Output Chan. 1)
-	dacc_set_trigger(dac, 1);
+	// Configure clock source for DAC (2 = TC0 Output Chan. 1)
+	dacc_set_trigger(dac, 2);
+
+	// Configure pins
+	PIO_Configure(g_APinDescription[DA0].pPort,
+			g_APinDescription[DA0].ulPinType,
+			g_APinDescription[DA0].ulPin,
+			g_APinDescription[DA0].ulPinConfiguration);
+	PIO_Configure(g_APinDescription[DA1].pPort,
+			g_APinDescription[DA1].ulPinType,
+			g_APinDescription[DA1].ulPin,
+			g_APinDescription[DA1].ulPinConfiguration);
+
+	currentBuffer = 0;
 }
 
 void AudioClass::end() {
@@ -70,11 +91,10 @@ void AudioClass::end() {
 	dacc_disable_channel(dac, 1);
 }
 
-size_t AudioClass::write(const uint8_t *buffer, size_t size) {
-
+size_t AudioClass::write(const uint32_t *buffer, size_t size) {
 	// Try the first PDC buffer
 	if ((dac->DACC_TCR == 0) && (dac->DACC_TNCR == 0)) {
-		dac->DACC_TPR = (uint32_t) buffer;
+		dac->DACC_TPR = (uint32_t) cook(buffer, size);
 		dac->DACC_TCR = size;
 		dac->DACC_PTCR = DACC_PTCR_TXTEN;
 		return size;
@@ -82,7 +102,7 @@ size_t AudioClass::write(const uint8_t *buffer, size_t size) {
 
 	// Try the second PDC buffer
 	if (dac->DACC_TNCR == 0) {
-		dac->DACC_TNPR = (uint32_t) buffer;
+		dac->DACC_TNPR = (uint32_t) cook(buffer, size);
 		dac->DACC_TNCR = size;
 		dac->DACC_PTCR = DACC_PTCR_TXTEN;
 		return size;
@@ -92,6 +112,22 @@ size_t AudioClass::write(const uint8_t *buffer, size_t size) {
 	return 0;
 }
 
+uint32_t *AudioClass::cook(const uint32_t *buffer, size_t size) {
+	if (currentBuffer == 0) {
+		// Use buffer0
+		for (int i = 0; i < size; i++)
+			buffer0[i] = buffer[i] | 0x10000000;
+		currentBuffer = 1;
+		return buffer0;
+	} else {
+		// Use buffer1
+		for (int i = 0; i < size; i++)
+			buffer1[i] = buffer[i] | 0x10000000;
+		currentBuffer = 0;
+		return buffer1;
+	}
+}
+
 AudioClass Audio(DACC_INTERFACE, DACC_INTERFACE_ID);
 
 //void DACC_IrqHandler(void) {
diff --git a/hardware/arduino/sam/libraries/Audio/Audio.h b/hardware/arduino/sam/libraries/Audio/Audio.h
index aae6f1363..39f0f289e 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.h
+++ b/hardware/arduino/sam/libraries/Audio/Audio.h
@@ -1,8 +1,17 @@
+/*
+ * Copyright (c) 2012 by Cristian Maglie <c.maglie@bug.st>
+ * Audio library for Arduino Due.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
+
 #ifndef AUDIO_H
 #define AUDIO_H
 
 #include "Arduino.h"
-//#include <inttypes.h>
 #include "Print.h"
 
 class AudioClass : public Print {
@@ -11,10 +20,19 @@ public:
 	void begin(uint32_t sampleRate);
 	void end();
 
-	virtual size_t write(uint8_t c) { write(&c, 1); };
-	virtual size_t write(const uint8_t *buffer, size_t size);
+	virtual size_t write(uint8_t c)                           { /* not implemented */ };
+	virtual size_t write(const uint8_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/4) * 4; };
+	virtual size_t write(const uint16_t *buffer, size_t size) { return write((uint32_t*) buffer, size/2) * 2; };
+	virtual size_t write(const int16_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/2) * 2; };
+	virtual size_t write(const uint32_t *buffer, size_t size);
 
 private:
+	uint32_t buffer0[1024];
+	uint32_t buffer1[1024];
+	int currentBuffer;
+
+	uint32_t *cook(const uint32_t *buffer, size_t size);
+
 	Dacc *dac;
 	uint32_t dacId;
 };

From de30e388438397133751a4bfe10a457a3523b061 Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Sun, 29 Jul 2012 01:57:12 +0200
Subject: [PATCH 3/4] Audio lib: added DAC class and DMA interrupt handling

---
 .../arduino/sam/cores/arduino/wiring_analog.c |  15 --
 .../arduino/sam/libraries/Audio/Audio.cpp     | 108 +-------------
 hardware/arduino/sam/libraries/Audio/Audio.h  |   8 +-
 hardware/arduino/sam/libraries/Audio/DAC.cpp  | 133 ++++++++++++++++++
 hardware/arduino/sam/libraries/Audio/DAC.h    |  30 ++++
 .../arduino/sam/system/libsam/include/tc.h    |   6 +
 .../arduino/sam/system/libsam/source/tc.c     |  12 ++
 .../arduino_due_x/libsam_sam3x8e_gcc_rel.a    | Bin 80258 -> 80658 bytes
 .../libsam_sam3x8e_gcc_rel.a.txt              |  61 ++++----
 .../sam/variants/arduino_due_x/variant.h      |   2 +
 10 files changed, 223 insertions(+), 152 deletions(-)
 create mode 100644 hardware/arduino/sam/libraries/Audio/DAC.cpp
 create mode 100644 hardware/arduino/sam/libraries/Audio/DAC.h

diff --git a/hardware/arduino/sam/cores/arduino/wiring_analog.c b/hardware/arduino/sam/cores/arduino/wiring_analog.c
index d5bf6dd2b..34e8d57df 100644
--- a/hardware/arduino/sam/cores/arduino/wiring_analog.c
+++ b/hardware/arduino/sam/cores/arduino/wiring_analog.c
@@ -151,21 +151,6 @@ uint32_t analogRead(uint32_t ulPin)
 	return ulValue;
 }
 
-static void TC_SetRA(Tc *tc, uint32_t chan, uint32_t v)
-{
-    tc->TC_CHANNEL[chan].TC_RA = v;
-}
-
-static void TC_SetRB(Tc *tc, uint32_t chan, uint32_t v)
-{
-    tc->TC_CHANNEL[chan].TC_RB = v;
-}
-
-static void TC_SetRC(Tc *tc, uint32_t chan, uint32_t v)
-{
-    tc->TC_CHANNEL[chan].TC_RC = v;
-}
-
 static void TC_SetCMR_ChannelA(Tc *tc, uint32_t chan, uint32_t v)
 {
 	tc->TC_CHANNEL[chan].TC_CMR = (tc->TC_CHANNEL[chan].TC_CMR & 0xFFF0FFFF) | v;
diff --git a/hardware/arduino/sam/libraries/Audio/Audio.cpp b/hardware/arduino/sam/libraries/Audio/Audio.cpp
index 0831d1876..cee8d77c0 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.cpp
+++ b/hardware/arduino/sam/libraries/Audio/Audio.cpp
@@ -10,106 +10,15 @@
 
 #include "Audio.h"
 
-static void TC_SetRA(Tc *tc, uint32_t chan, uint32_t v) {
-	tc->TC_CHANNEL[chan].TC_RA = v;
-}
-
-static void TC_SetRB(Tc *tc, uint32_t chan, uint32_t v) {
-	tc->TC_CHANNEL[chan].TC_RB = v;
-}
-
-static void TC_SetRC(Tc *tc, uint32_t chan, uint32_t v) {
-	tc->TC_CHANNEL[chan].TC_RC = v;
-}
-
 void AudioClass::begin(uint32_t sampleRate) {
-	// Enable clock for DAC
-	pmc_enable_periph_clk(dacId);
-
-	dacc_reset(dac);
-
-	// Set transfer mode to double word
-	dacc_set_transfer_mode(dac, 1);
-
-	// Power save:
-	// sleep mode  - 0 (disabled)
-	// fast wakeup - 0 (disabled)
-	dacc_set_power_save(dac, 0, 0);
-
-	// ADC refresh/startup timings:
-	// refresh        - 0x08 (1024*8 dacc clocks)
-	// max speed mode -    0 (disabled)
-	// startup time   - 0x10 (1024 dacc clocks)
-	dacc_set_timing(dac, 0x08, 0, DACC_MR_STARTUP_1024);
-
-	// Flexible channel selection with tags
-	dacc_enable_flexible_selection(dac);
-
-	// Set up analog current
-	dacc_set_analog_control(dac,
-			DACC_ACR_IBCTLCH0(0x02) |
-			DACC_ACR_IBCTLCH1(0x02) |
-			DACC_ACR_IBCTLDACCORE(0x01));
-
-	// Enable output channels
-	dacc_enable_channel(dac, 0);
-	dacc_enable_channel(dac, 1);
-
-
-	// Configure Timer Counter to trigger DAC
-	// --------------------------------------
-	pmc_enable_periph_clk(ID_TC1);
-	TC_Configure(TC0, 1,
-		TC_CMR_TCCLKS_TIMER_CLOCK2 |  // Clock at MCR/8
-		TC_CMR_WAVE |                 // Waveform mode
-		TC_CMR_WAVSEL_UP_RC |         // Counter running up and reset when equals to RC
-		TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR);
-	const uint32_t TC = VARIANT_MCK / 8 / sampleRate;
-	TC_SetRA(TC0, 1, TC / 2);
-	TC_SetRC(TC0, 1, TC);
-	TC_Start(TC0, 1);
-
-	// Configure clock source for DAC (2 = TC0 Output Chan. 1)
-	dacc_set_trigger(dac, 2);
-
-	// Configure pins
-	PIO_Configure(g_APinDescription[DA0].pPort,
-			g_APinDescription[DA0].ulPinType,
-			g_APinDescription[DA0].ulPin,
-			g_APinDescription[DA0].ulPinConfiguration);
-	PIO_Configure(g_APinDescription[DA1].pPort,
-			g_APinDescription[DA1].ulPinType,
-			g_APinDescription[DA1].ulPin,
-			g_APinDescription[DA1].ulPinConfiguration);
+	const uint32_t T = VARIANT_MCK / sampleRate;
+	dac->begin(T);
 
 	currentBuffer = 0;
 }
 
 void AudioClass::end() {
-	TC_Stop(TC0, 1);
-	dacc_disable_channel(dac, 0);
-	dacc_disable_channel(dac, 1);
-}
-
-size_t AudioClass::write(const uint32_t *buffer, size_t size) {
-	// Try the first PDC buffer
-	if ((dac->DACC_TCR == 0) && (dac->DACC_TNCR == 0)) {
-		dac->DACC_TPR = (uint32_t) cook(buffer, size);
-		dac->DACC_TCR = size;
-		dac->DACC_PTCR = DACC_PTCR_TXTEN;
-		return size;
-	}
-
-	// Try the second PDC buffer
-	if (dac->DACC_TNCR == 0) {
-		dac->DACC_TNPR = (uint32_t) cook(buffer, size);
-		dac->DACC_TNCR = size;
-		dac->DACC_PTCR = DACC_PTCR_TXTEN;
-		return size;
-	}
-
-	// PDC buffers full, try again later...
-	return 0;
+	dac->end();
 }
 
 uint32_t *AudioClass::cook(const uint32_t *buffer, size_t size) {
@@ -128,13 +37,4 @@ uint32_t *AudioClass::cook(const uint32_t *buffer, size_t size) {
 	}
 }
 
-AudioClass Audio(DACC_INTERFACE, DACC_INTERFACE_ID);
-
-//void DACC_IrqHandler(void) {
-//	uint32_t sr = DACC_INTERFACE->DACC_ISR;
-//
-//	if (sr & DACC_ISR_ENDTX) {
-//		/* End of transmission */
-//		Audio.write(wBuffer, SAMPLES);
-//	}
-//}
+AudioClass Audio(DAC);
diff --git a/hardware/arduino/sam/libraries/Audio/Audio.h b/hardware/arduino/sam/libraries/Audio/Audio.h
index 39f0f289e..4eedd5717 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.h
+++ b/hardware/arduino/sam/libraries/Audio/Audio.h
@@ -13,10 +13,11 @@
 
 #include "Arduino.h"
 #include "Print.h"
+#include "DAC.h"
 
 class AudioClass : public Print {
 public:
-	AudioClass(Dacc *_dac, uint32_t _dacId) : dac(_dac), dacId(_dacId) { };
+	AudioClass(DACClass &_dac) : dac(&_dac) { };
 	void begin(uint32_t sampleRate);
 	void end();
 
@@ -24,7 +25,7 @@ public:
 	virtual size_t write(const uint8_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/4) * 4; };
 	virtual size_t write(const uint16_t *buffer, size_t size) { return write((uint32_t*) buffer, size/2) * 2; };
 	virtual size_t write(const int16_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/2) * 2; };
-	virtual size_t write(const uint32_t *buffer, size_t size);
+	virtual size_t write(const uint32_t *buffer, size_t size) { return dac->queueBuffer(cook(buffer,size), size); };
 
 private:
 	uint32_t buffer0[1024];
@@ -33,8 +34,7 @@ private:
 
 	uint32_t *cook(const uint32_t *buffer, size_t size);
 
-	Dacc *dac;
-	uint32_t dacId;
+	DACClass *dac;
 };
 
 extern AudioClass Audio;
diff --git a/hardware/arduino/sam/libraries/Audio/DAC.cpp b/hardware/arduino/sam/libraries/Audio/DAC.cpp
new file mode 100644
index 000000000..ae9056db0
--- /dev/null
+++ b/hardware/arduino/sam/libraries/Audio/DAC.cpp
@@ -0,0 +1,133 @@
+
+#include <DAC.h>
+
+void DACClass::begin(uint32_t period) {
+	// Enable clock for DAC
+	pmc_enable_periph_clk(dacId);
+
+	dacc_reset(dac);
+
+	// Set transfer mode to double word
+	dacc_set_transfer_mode(dac, 1);
+
+	// Power save:
+	// sleep mode  - 0 (disabled)
+	// fast wakeup - 0 (disabled)
+	dacc_set_power_save(dac, 0, 0);
+
+	// DAC refresh/startup timings:
+	// refresh        - 0x08 (1024*8 dacc clocks)
+	// max speed mode -    0 (disabled)
+	// startup time   - 0x10 (1024 dacc clocks)
+	dacc_set_timing(dac, 0x08, 0, DACC_MR_STARTUP_1024);
+
+	// Flexible channel selection with tags
+	dacc_enable_flexible_selection(dac);
+
+	// Set up analog current
+	dacc_set_analog_control(dac,
+			DACC_ACR_IBCTLCH0(0x02) |
+			DACC_ACR_IBCTLCH1(0x02) |
+			DACC_ACR_IBCTLDACCORE(0x01));
+
+	// Enable output channels
+	dacc_enable_channel(dac, 0);
+	dacc_enable_channel(dac, 1);
+
+	// Configure Timer Counter to trigger DAC
+	// --------------------------------------
+	pmc_enable_periph_clk(ID_TC1);
+	TC_Configure(TC0, 1,
+		TC_CMR_TCCLKS_TIMER_CLOCK2 |  // Clock at MCR/8
+		TC_CMR_WAVE |                 // Waveform mode
+		TC_CMR_WAVSEL_UP_RC |         // Counter running up and reset when equals to RC
+		TC_CMR_ACPA_SET | TC_CMR_ACPC_CLEAR);
+	const uint32_t TC = period / 8;
+	TC_SetRA(TC0, 1, TC / 2);
+	TC_SetRC(TC0, 1, TC);
+	TC_Start(TC0, 1);
+
+	// Configure clock source for DAC (2 = TC0 Output Chan. 1)
+	dacc_set_trigger(dac, 2);
+
+	// Configure pins
+	PIO_Configure(g_APinDescription[DA0].pPort,
+			g_APinDescription[DA0].ulPinType,
+			g_APinDescription[DA0].ulPin,
+			g_APinDescription[DA0].ulPinConfiguration);
+	PIO_Configure(g_APinDescription[DA1].pPort,
+			g_APinDescription[DA1].ulPinType,
+			g_APinDescription[DA1].ulPin,
+			g_APinDescription[DA1].ulPinConfiguration);
+
+	// Enable interrupt controller for DAC
+	dacc_disable_interrupt(dac, 0xFFFFFFFF);
+	NVIC_DisableIRQ(isrId);
+	NVIC_ClearPendingIRQ(isrId);
+	NVIC_SetPriority(isrId, 0);
+	NVIC_EnableIRQ(isrId);
+}
+
+void DACClass::end() {
+	TC_Stop(TC0, 1);
+	NVIC_DisableIRQ(isrId);
+	dacc_disable_channel(dac, 0);
+	dacc_disable_channel(dac, 1);
+}
+
+bool DACClass::canQueue() {
+	if ((dac->DACC_TCR == 0) && (dac->DACC_TNCR == 0))
+		return true;
+	if (dac->DACC_TNCR == 0)
+		return true;
+	return false;
+}
+
+size_t DACClass::queueBuffer(const uint32_t *buffer, size_t size) {
+	// Try the first PDC buffer
+	if ((dac->DACC_TCR == 0) && (dac->DACC_TNCR == 0)) {
+		dac->DACC_TPR = (uint32_t) buffer;
+		dac->DACC_TCR = size;
+		dac->DACC_PTCR = DACC_PTCR_TXTEN;
+		if (cb)
+			dacc_enable_interrupt(dac, DACC_IER_ENDTX);
+		return size;
+	}
+
+	// Try the second PDC buffer
+	if (dac->DACC_TNCR == 0) {
+		dac->DACC_TNPR = (uint32_t) buffer;
+		dac->DACC_TNCR = size;
+		dac->DACC_PTCR = DACC_PTCR_TXTEN;
+		if (cb)
+			dacc_enable_interrupt(dac, DACC_IER_ENDTX);
+		return size;
+	}
+
+	// PDC buffers full, try again later...
+	return 0;
+}
+
+void DACClass::setOnQueueFree_CB(OnQueueFree_CB _cb) {
+	cb = _cb;
+	if (cb) {
+		dacc_enable_interrupt(dac, DACC_IER_ENDTX);
+	} else {
+		dacc_disable_interrupt(dac, DACC_IDR_ENDTX);
+	}
+}
+
+void DACClass::onService() {
+	uint32_t sr = dac->DACC_ISR;
+	if (sr & DACC_ISR_ENDTX) {
+		dacc_disable_interrupt(dac, DACC_IDR_ENDTX);
+		if (cb) cb();
+	}
+}
+
+DACClass DAC(DACC_INTERFACE, DACC_INTERFACE_ID, DACC_ISR_ID);
+
+void DACC_ISR_HANDLER(void) {
+	DAC.onService();
+}
+
diff --git a/hardware/arduino/sam/libraries/Audio/DAC.h b/hardware/arduino/sam/libraries/Audio/DAC.h
new file mode 100644
index 000000000..925fb2164
--- /dev/null
+++ b/hardware/arduino/sam/libraries/Audio/DAC.h
@@ -0,0 +1,30 @@
+
+#ifndef DAC_INCLUDED
+#define DAC_INCLUDED
+
+#include "Arduino.h"
+
+typedef void (*OnQueueFree_CB)(void);
+
+class DACClass
+{
+public:
+	DACClass(Dacc *_dac, uint32_t _dacId, IRQn_Type _isrId) :
+		dac(_dac), dacId(_dacId), isrId(_isrId), cb(NULL) { };
+	void begin(uint32_t period);
+	void end();
+	bool canQueue();
+	size_t queueBuffer(const uint32_t *buffer, size_t size);
+	void setOnQueueFree_CB(OnQueueFree_CB _cb);
+	void onService();
+
+private:
+	Dacc *dac;
+	uint32_t dacId;
+	IRQn_Type isrId;
+	OnQueueFree_CB cb;
+};
+
+extern DACClass DAC;
+
+#endif
diff --git a/hardware/arduino/sam/system/libsam/include/tc.h b/hardware/arduino/sam/system/libsam/include/tc.h
index 92c0b0367..dc0aa43b6 100644
--- a/hardware/arduino/sam/system/libsam/include/tc.h
+++ b/hardware/arduino/sam/system/libsam/include/tc.h
@@ -68,6 +68,12 @@ extern void TC_Stop( Tc *pTc, uint32_t dwChannel ) ;
 
 extern uint32_t TC_FindMckDivisor( uint32_t dwFreq, uint32_t dwMCk, uint32_t *dwDiv, uint32_t *dwTcClks, uint32_t dwBoardMCK ) ;
 
+extern void TC_SetRA(Tc *tc, uint32_t chan, uint32_t v) ;
+
+extern void TC_SetRB(Tc *tc, uint32_t chan, uint32_t v) ;
+
+extern void TC_SetRC(Tc *tc, uint32_t chan, uint32_t v) ;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/hardware/arduino/sam/system/libsam/source/tc.c b/hardware/arduino/sam/system/libsam/source/tc.c
index 35439db5a..87f5dd800 100644
--- a/hardware/arduino/sam/system/libsam/source/tc.c
+++ b/hardware/arduino/sam/system/libsam/source/tc.c
@@ -173,3 +173,15 @@ extern uint32_t TC_FindMckDivisor( uint32_t dwFreq, uint32_t dwMCk, uint32_t *dw
     return 1 ;
 }
 
+void TC_SetRA(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RA = v;
+}
+
+void TC_SetRB(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RB = v;
+}
+
+void TC_SetRC(Tc *tc, uint32_t chan, uint32_t v) {
+	tc->TC_CHANNEL[chan].TC_RC = v;
+}
+
diff --git a/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a b/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a
index a36253ea4e6caaf6178117c815d1a2c3ca880655..63e201ea8c9b84212ba8348008b004607e991b60 100644
GIT binary patch
delta 5064
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diff --git a/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a.txt b/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a.txt
index 1ed7a440f..32b563e76 100644
--- a/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a.txt
+++ b/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a.txt
@@ -72,7 +72,7 @@ pmc.o:
 00000000 T pmc_switch_udpck_to_upllck
 
 pwmc.o:
-00000000 r C.9.7204
+00000000 r C.9.7219
 00000000 t FindClockConfiguration
 00000000 T PWMC_ConfigureChannel
 00000000 T PWMC_ConfigureChannelExt
@@ -100,14 +100,14 @@ pwmc.o:
 00000000 T PWMC_SetSyncChannelUpdateUnlock
 00000000 T PWMC_WriteBuffer
          U __assert_func
-00000000 r __func__.5914
-00000000 r __func__.5925
-00000000 r __func__.5940
-00000000 r __func__.5951
-00000000 r __func__.5962
-00000000 r __func__.5969
-00000000 r __func__.6053
-00000000 r __func__.6059
+00000000 r __func__.5926
+00000000 r __func__.5937
+00000000 r __func__.5952
+00000000 r __func__.5963
+00000000 r __func__.5974
+00000000 r __func__.5981
+00000000 r __func__.6065
+00000000 r __func__.6071
 
 rtc.o:
 00000000 T RTC_ClearSCCR
@@ -123,9 +123,9 @@ rtc.o:
 00000000 T RTC_SetTime
 00000000 T RTC_SetTimeAlarm
          U __assert_func
-00000000 r __func__.5911
-00000000 r __func__.5920
-00000000 r __func__.5925
+00000000 r __func__.5923
+00000000 r __func__.5932
+00000000 r __func__.5937
 
 rtt.o:
 00000000 T RTT_EnableIT
@@ -134,8 +134,8 @@ rtt.o:
 00000000 T RTT_SetAlarm
 00000000 T RTT_SetPrescaler
          U __assert_func
-00000000 r __func__.5918
-00000000 r __func__.5926
+00000000 r __func__.5930
+00000000 r __func__.5938
 
 spi.o:
 00000000 T SPI_Configure
@@ -153,12 +153,15 @@ spi.o:
 tc.o:
 00000000 T TC_Configure
 00000000 T TC_FindMckDivisor
+00000000 T TC_SetRA
+00000000 T TC_SetRB
+00000000 T TC_SetRC
 00000000 T TC_Start
 00000000 T TC_Stop
          U __assert_func
-00000000 r __func__.5913
-00000000 r __func__.5919
 00000000 r __func__.5925
+00000000 r __func__.5931
+00000000 r __func__.5937
 
 timetick.o:
 00000000 T GetTickCount
@@ -185,18 +188,18 @@ twi.o:
 00000000 T TWI_TransferComplete
 00000000 T TWI_WriteByte
          U __assert_func
-00000000 r __func__.6286
-00000000 r __func__.6301
-00000000 r __func__.6305
-00000000 r __func__.6312
-00000000 r __func__.6316
-00000000 r __func__.6321
-00000000 r __func__.6329
-00000000 r __func__.6343
-00000000 r __func__.6348
-00000000 r __func__.6352
-00000000 r __func__.6357
-00000000 r __func__.6361
+00000000 r __func__.6298
+00000000 r __func__.6313
+00000000 r __func__.6317
+00000000 r __func__.6324
+00000000 r __func__.6328
+00000000 r __func__.6333
+00000000 r __func__.6341
+00000000 r __func__.6355
+00000000 r __func__.6360
+00000000 r __func__.6364
+00000000 r __func__.6369
+00000000 r __func__.6373
 
 usart.o:
 00000000 T USART_Configure
@@ -215,7 +218,7 @@ usart.o:
 00000000 T USART_Write
 00000000 T USART_WriteBuffer
          U __assert_func
-00000000 r __func__.6207
+00000000 r __func__.6219
 
 wdt.o:
 00000000 T WDT_Disable
diff --git a/hardware/arduino/sam/variants/arduino_due_x/variant.h b/hardware/arduino/sam/variants/arduino_due_x/variant.h
index a99f7807a..e8101b438 100644
--- a/hardware/arduino/sam/variants/arduino_due_x/variant.h
+++ b/hardware/arduino/sam/variants/arduino_due_x/variant.h
@@ -171,6 +171,8 @@ static const uint8_t CANTX0 = 69;
  */
 #define DACC_INTERFACE		DACC
 #define DACC_INTERFACE_ID	ID_DACC
+#define DACC_ISR_HANDLER    DACC_Handler
+#define DACC_ISR_ID         DACC_IRQn
 
 /*
  * PWM

From 5131431d966f599fca4d41ce0440aeb9141aada5 Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Wed, 1 Aug 2012 11:51:29 +0200
Subject: [PATCH 4/4] Some experiments about Audio buffering. DAC class added.

---
 .../arduino/sam/libraries/Audio/Audio.cpp     | 127 +++++++++++++++---
 hardware/arduino/sam/libraries/Audio/Audio.h  |  32 +++--
 hardware/arduino/sam/libraries/Audio/DAC.cpp  |  29 ++--
 hardware/arduino/sam/libraries/Audio/DAC.h    |  20 ++-
 4 files changed, 172 insertions(+), 36 deletions(-)

diff --git a/hardware/arduino/sam/libraries/Audio/Audio.cpp b/hardware/arduino/sam/libraries/Audio/Audio.cpp
index cee8d77c0..bd8d99186 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.cpp
+++ b/hardware/arduino/sam/libraries/Audio/Audio.cpp
@@ -10,31 +10,126 @@
 
 #include "Audio.h"
 
-void AudioClass::begin(uint32_t sampleRate) {
-	const uint32_t T = VARIANT_MCK / sampleRate;
-	dac->begin(T);
+class LockDAC {
+public:
+	LockDAC(DACClass *_dac) : dac(_dac)
+	           { dac->disableInterrupts(); };
+	~LockDAC() { dac->enableInterrupts(); };
+	DACClass *dac;
+};
 
-	currentBuffer = 0;
+void AudioClass::begin(uint32_t sampleRate, uint32_t msPreBuffer) {
+	// Allocate a buffer to keep msPreBuffer milliseconds of audio
+	bufferSize = msPreBuffer * sampleRate / 1000;
+	if (bufferSize < 2048)
+		bufferSize = 2048;
+	buffer = (uint32_t *) malloc(bufferSize * sizeof(uint32_t));
+	last = buffer + bufferSize;
+
+	// Buffering starts from the beginning
+	running = last;
+	current = buffer;
+	next = buffer;
+
+	// Run DAC
+	dac->begin(VARIANT_MCK / sampleRate);
+	dac->setOnTransmitEnd_CB(onTransmitEnd, this);
 }
 
 void AudioClass::end() {
 	dac->end();
+	free(buffer);
 }
 
-uint32_t *AudioClass::cook(const uint32_t *buffer, size_t size) {
-	if (currentBuffer == 0) {
-		// Use buffer0
-		for (int i = 0; i < size; i++)
-			buffer0[i] = buffer[i] | 0x10000000;
-		currentBuffer = 1;
-		return buffer0;
+size_t AudioClass::write(const uint32_t *data, size_t size) {
+	LockDAC lock(dac);
+	//Serial1.print("WRI(");
+	const uint32_t TAG = 0x10000000;
+	int i;
+	for (i=0; i < size && next != running; i++) {
+		*next = data[i] | TAG;
+		next++;
+
+		// Wrap around circular buffer
+		if (next == last)
+			next = buffer;
+	}
+	debug();
+	if (dac->canQueue()) {
+		enqueue();
+		debug();
+	}
+	//Serial1.print(")");
+	return i;
+}
+
+void AudioClass::enqueue() {
+	if (!dac->canQueue())
+		// DMA queue full
+		return;
+
+	if (current == next)
+		// No data to enqueue
+		return;
+
+	// If wrapping happened
+	if (next < current) {
+
+		uint32_t size = last - current;
+
+		if (size < 1024) {
+			// enqueue the last part of the circular buffer
+			dac->queueBuffer(current, size);
+			current = buffer;
+			next = buffer;
+		} else {
+			// Enqueue only a block of 512
+			dac->queueBuffer(current, 512);
+			current += 512;
+		}
+		return;
+	}
+
+	bool aboutToWrap = (last - next) < 512;
+	uint32_t size = next - current;
+
+	// If buffered data is less than 512 bytes
+	if (size < 512) {
+
+		// Enqueue all
+		dac->queueBuffer(current, size);
+
+		if (aboutToWrap)
+			next = buffer;
+		current = next;
+
 	} else {
-		// Use buffer1
-		for (int i = 0; i < size; i++)
-			buffer1[i] = buffer[i] | 0x10000000;
-		currentBuffer = 0;
-		return buffer1;
+
+		if (aboutToWrap && size < 1024) {
+			// Enqueue all
+			dac->queueBuffer(current, size);
+			next = buffer;
+			current = buffer;
+		} else {
+			// Enqueue only a block of 512
+			dac->queueBuffer(current, 512);
+			current += 512;
+		}
+
 	}
 }
 
+void AudioClass::onTransmitEnd(void *me) {
+	AudioClass *audio = reinterpret_cast<AudioClass *>(me);
+
+	//Serial1.print("INT(");
+	audio->enqueue();
+
+	// Update running pointer
+	audio->running = audio->dac->getCurrentQueuePointer();
+
+	audio->debug();
+	//Serial1.print(")");
+}
+
 AudioClass Audio(DAC);
diff --git a/hardware/arduino/sam/libraries/Audio/Audio.h b/hardware/arduino/sam/libraries/Audio/Audio.h
index 4eedd5717..93ae0e780 100644
--- a/hardware/arduino/sam/libraries/Audio/Audio.h
+++ b/hardware/arduino/sam/libraries/Audio/Audio.h
@@ -18,19 +18,33 @@
 class AudioClass : public Print {
 public:
 	AudioClass(DACClass &_dac) : dac(&_dac) { };
-	void begin(uint32_t sampleRate);
+	void begin(uint32_t sampleRate, uint32_t msPreBuffer);
 	void end();
 
-	virtual size_t write(uint8_t c)                           { /* not implemented */ };
-	virtual size_t write(const uint8_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/4) * 4; };
-	virtual size_t write(const uint16_t *buffer, size_t size) { return write((uint32_t*) buffer, size/2) * 2; };
-	virtual size_t write(const int16_t *buffer, size_t size)  { return write((uint32_t*) buffer, size/2) * 2; };
-	virtual size_t write(const uint32_t *buffer, size_t size) { return dac->queueBuffer(cook(buffer,size), size); };
+	virtual size_t write(uint8_t c)                         { /* not implemented */ };
+	virtual size_t write(const uint8_t *data, size_t size)  { return write(reinterpret_cast<const uint32_t*>(data), size/4) * 4; };
+	virtual size_t write(const uint16_t *data, size_t size) { return write(reinterpret_cast<const uint32_t*>(data), size/2) * 2; };
+	virtual size_t write(const int16_t *data, size_t size)  { return write(reinterpret_cast<const uint32_t*>(data), size/2) * 2; };
+	virtual size_t write(const uint32_t *data, size_t size);
 
+	void debug() {
+//		Serial1.print(running-buffer, DEC);
+//		Serial1.print(" ");
+//		Serial1.print(current-buffer, DEC);
+//		Serial1.print(" ");
+//		Serial1.print(next-buffer, DEC);
+//		Serial1.print(" ");
+//		Serial1.println(last-buffer, DEC);
+	}
 private:
-	uint32_t buffer0[1024];
-	uint32_t buffer1[1024];
-	int currentBuffer;
+	void enqueue();
+	static void onTransmitEnd(void *me);
+	uint32_t bufferSize;
+	uint32_t *buffer;
+	uint32_t *last;
+	uint32_t * volatile running;
+	uint32_t * volatile current;
+	uint32_t * volatile next;
 
 	uint32_t *cook(const uint32_t *buffer, size_t size);
 
diff --git a/hardware/arduino/sam/libraries/Audio/DAC.cpp b/hardware/arduino/sam/libraries/Audio/DAC.cpp
index ae9056db0..766d7e4c4 100644
--- a/hardware/arduino/sam/libraries/Audio/DAC.cpp
+++ b/hardware/arduino/sam/libraries/Audio/DAC.cpp
@@ -1,3 +1,12 @@
+/*
+ * Copyright (c) 2012 by Cristian Maglie <c.maglie@bug.st>
+ * DAC library for Arduino Due.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
 
 #include <DAC.h>
 
@@ -108,21 +117,25 @@ size_t DACClass::queueBuffer(const uint32_t *buffer, size_t size) {
 	return 0;
 }
 
-void DACClass::setOnQueueFree_CB(OnQueueFree_CB _cb) {
+uint32_t *DACClass::getCurrentQueuePointer() {
+	return reinterpret_cast<uint32_t *>(dac->DACC_TPR);
+}
+
+void DACClass::setOnTransmitEnd_CB(OnTransmitEnd_CB _cb, void *_data) {
 	cb = _cb;
-	if (cb) {
-		dacc_enable_interrupt(dac, DACC_IER_ENDTX);
-	} else {
+	cbData = _data;
+	if (!cb)
 		dacc_disable_interrupt(dac, DACC_IDR_ENDTX);
-	}
 }
 
 void DACClass::onService() {
 	uint32_t sr = dac->DACC_ISR;
-	if (sr & DACC_ISR_ENDTX) {
+//	if (sr & DACC_ISR_ENDTX) {
+		// There is a free slot, enqueue data
 		dacc_disable_interrupt(dac, DACC_IDR_ENDTX);
-		if (cb) cb();
-	}
+		if (cb)
+			cb(cbData);
+//	}
 }
 
 DACClass DAC(DACC_INTERFACE, DACC_INTERFACE_ID, DACC_ISR_ID);
diff --git a/hardware/arduino/sam/libraries/Audio/DAC.h b/hardware/arduino/sam/libraries/Audio/DAC.h
index 925fb2164..d49658415 100644
--- a/hardware/arduino/sam/libraries/Audio/DAC.h
+++ b/hardware/arduino/sam/libraries/Audio/DAC.h
@@ -1,10 +1,19 @@
+/*
+ * Copyright (c) 2012 by Cristian Maglie <c.maglie@bug.st>
+ * DAC library for Arduino Due.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
 
 #ifndef DAC_INCLUDED
 #define DAC_INCLUDED
 
 #include "Arduino.h"
 
-typedef void (*OnQueueFree_CB)(void);
+typedef void (*OnTransmitEnd_CB)(void *data);
 
 class DACClass
 {
@@ -15,14 +24,19 @@ public:
 	void end();
 	bool canQueue();
 	size_t queueBuffer(const uint32_t *buffer, size_t size);
-	void setOnQueueFree_CB(OnQueueFree_CB _cb);
+	uint32_t *getCurrentQueuePointer();
+	void setOnTransmitEnd_CB(OnTransmitEnd_CB _cb, void *data);
 	void onService();
 
+	void enableInterrupts()  { NVIC_EnableIRQ(isrId); };
+	void disableInterrupts() { NVIC_DisableIRQ(isrId); };
+
 private:
 	Dacc *dac;
 	uint32_t dacId;
 	IRQn_Type isrId;
-	OnQueueFree_CB cb;
+	OnTransmitEnd_CB cb;
+	void *cbData;
 };
 
 extern DACClass DAC;