Add AudioOutputAnalog object, for audio to Teensy 3.1 DAC

Audio.cpp

 
 
 
+
+
 /******************************************************************/
 
 
 
 
 
+/******************************************************************/
+
+
+
+// #define PDB_CONFIG (PDB_SC_TRGSEL(15) | PDB_SC_PDBEN | PDB_SC_CONT)
+// #define PDB_PERIOD 1087 // 48e6 / 44100
+
+#if defined(__MK20DX256__) && defined(DMA_TCD4_SADDR)
+
+DMAMEM static uint16_t dac_buffer[AUDIO_BLOCK_SAMPLES*2];
+audio_block_t * AudioOutputAnalog::block_left_1st = NULL;
+audio_block_t * AudioOutputAnalog::block_left_2nd = NULL;
+bool AudioOutputAnalog::update_responsibility = false;
+
+void AudioOutputAnalog::begin(void)
+{
+	SIM_SCGC2 |= SIM_SCGC2_DAC0;
+	DAC0_C0 = DAC_C0_DACEN | DAC_C0_DACRFS; // 3.3V VDDA is DACREF_2
+	// slowly ramp up to DC voltage, approx 1/4 second
+	for (int16_t i=0; i<2047; i++) {
+		*(int16_t *)&(DAC0_DAT0L) = i;
+		delayMicroseconds(262);
+	}
+
+	// set the programmable delay block to trigger DMA requests
+	SIM_SCGC6 |= SIM_SCGC6_PDB;
+	PDB0_IDLY = 50; // TODO: is this ok?
+	PDB0_MOD = PDB_PERIOD;
+	PDB0_SC = PDB_CONFIG | PDB_SC_LDOK;
+	PDB0_SC = PDB_CONFIG | PDB_SC_SWTRIG | PDB_SC_PDBIE | PDB_SC_DMAEN;
+	//PDB0_SC = PDB_CONFIG | PDB_SC_SWTRIG | PDB_SC_PDBIE;
+	//NVIC_ENABLE_IRQ(IRQ_PDB);
+#if 1
+	SIM_SCGC7 |= SIM_SCGC7_DMA;
+	SIM_SCGC6 |= SIM_SCGC6_DMAMUX;
+	DMA_CR = 0;
+	DMA_TCD4_SADDR = dac_buffer;
+	DMA_TCD4_SOFF = 2;
+	DMA_TCD4_ATTR = DMA_TCD_ATTR_SSIZE(1) | DMA_TCD_ATTR_DSIZE(1);
+	DMA_TCD4_NBYTES_MLNO = 2;
+	DMA_TCD4_SLAST = -sizeof(dac_buffer);
+	DMA_TCD4_DADDR = &DAC0_DAT0L;
+	DMA_TCD4_DOFF = 0;
+	DMA_TCD4_CITER_ELINKNO = sizeof(dac_buffer) / 2;
+	DMA_TCD4_DLASTSGA = 0;
+	DMA_TCD4_BITER_ELINKNO = sizeof(dac_buffer) / 2;
+	DMA_TCD4_CSR = DMA_TCD_CSR_INTHALF | DMA_TCD_CSR_INTMAJOR;
+
+	DMAMUX0_CHCFG4 = DMAMUX_DISABLE;
+	DMAMUX0_CHCFG4 = DMAMUX_SOURCE_PDB | DMAMUX_ENABLE;
+	update_responsibility = update_setup();
+	DMA_SERQ = 4;
+
+	NVIC_ENABLE_IRQ(IRQ_DMA_CH4);
+#endif
+}
+
+//void pdb_isr(void)
+//{
+//	static uint16_t val=0;
+//
+//	PDB0_SC = PDB_CONFIG | PDB_SC_PDBIE;
+//	if (val == 0) val = 4095;  // testing only, full scale 22.05 kHz output
+//	else val = 0;
+//	DAC0_DAT0L = val & 255;
+//	DAC0_DATH = val >> 8;
+//}
+
+void AudioOutputAnalog::update(void)
+{
+	audio_block_t *block;
+	block = receiveReadOnly(0); // input 0
+	if (block) {
+		__disable_irq();
+		if (block_left_1st == NULL) {
+			block_left_1st = block;
+			__enable_irq();
+		} else if (block_left_2nd == NULL) {
+			block_left_2nd = block;
+			__enable_irq();
+		} else {
+			audio_block_t *tmp = block_left_1st;
+			block_left_1st = block_left_2nd;
+			block_left_2nd = block;
+			__enable_irq();
+			release(tmp);
+		}
+	}
+}
+
+// TODO: the DAC has much higher bandwidth than the datasheet says
+// can we output a 2X oversampled output, for easier filtering?
 
+void dma_ch4_isr(void)
+{
+	const int16_t *src, *end;
+	int16_t *dest;
+	audio_block_t *block;
+	uint32_t saddr, offset;
 
+	saddr = (uint32_t)DMA_TCD4_SADDR;
+        DMA_CINT = 4;
+	if (saddr < (uint32_t)dac_buffer + sizeof(dac_buffer) / 2) {
+		// DMA is transmitting the first half of the buffer
+		// so we must fill the second half
+		dest = (int16_t *)&dac_buffer[AUDIO_BLOCK_SAMPLES];
+		end = (int16_t *)&dac_buffer[AUDIO_BLOCK_SAMPLES*2];
+		if (AudioOutputAnalog::update_responsibility) AudioStream::update_all();
+	} else {
+		// DMA is transmitting the second half of the buffer
+		// so we must fill the first half
+		dest = (int16_t *)dac_buffer;
+		end = (int16_t *)&dac_buffer[AUDIO_BLOCK_SAMPLES];
+	}
+	block = AudioOutputAnalog::block_left_1st;
+	if (block) {
+		src = &block->data[offset];
+		do {
+			// TODO: this should probably dither
+			*dest++ = ((*src++) + 32767) >> 4; // TODO: optimize
+		} while (dest < end);
+		AudioStream::release(block);
+		AudioOutputAnalog::block_left_1st = AudioOutputAnalog::block_left_2nd;
+		AudioOutputAnalog::block_left_2nd = NULL;
+	} else {
+		do {
+			*dest++ = 2047;
+		} while (dest < end);
+	}
+	Serial.print(".");
+}
 
+#else
 
 
+void AudioOutputAnalog::begin(void)
+{
+}
 
+void AudioOutputAnalog::update(void)
+{
+	audio_block_t *block;
+	block = receiveReadOnly(0); // input 0
+	if (block) release(block);
+}
 
+#endif // defined(__MK20DX256__) && defined(DMA_TCD4_SADDR)
 
 
 

Audio.h

 
 
 
+
+
+class AudioOutputAnalog : public AudioStream
+{
+public:
+	AudioOutputAnalog(void) : AudioStream(1, inputQueueArray) { begin(); }
+	virtual void update(void);
+	void begin(void);
+	friend void dma_ch4_isr(void);
+private:
+	static audio_block_t *block_left_1st;
+	static audio_block_t *block_left_2nd;
+	static bool update_responsibility;
+	audio_block_t *inputQueueArray[1];
+};
+
+
+
+
+
 class AudioPrint : public AudioStream
 {
 public:

examples/PlayFromSketch/PlayFromSketch.ino

 AudioPlayMemory    sound5;
 AudioMixer4        mix1;    // two 4-channel mixers are needed in
 AudioMixer4        mix2;    // tandem to combine 6 audio sources
-AudioOutputI2S     dac;
+AudioOutputI2S     headphones;
+AudioOutputAnalog  dac;     // play to both I2S audio board and on-chip DAC
 
 // Create Audio connections between the components
 //
 AudioConnection c5(mix1, 0, mix2, 0);   // output of mix1 into 1st input on mix2
 AudioConnection c6(sound4, 0, mix2, 1);
 AudioConnection c7(sound5, 0, mix2, 2);
-AudioConnection c8(mix2, 0, dac, 0);
-AudioConnection c9(mix2, 0, dac, 1);
+AudioConnection c8(mix2, 0, headphones, 0);
+AudioConnection c9(mix2, 0, headphones, 1);
+AudioConnection c10(mix2, 0, dac, 0);
 
 // Create an object to control the audio shield.
 //