USB audio on Teensy 4.0 (more work in progress)

teensy4/usb.c

 	if (cb) endpointN_notify_mask |= (1 << (ep + 16));
 }
 
+void usb_config_rx_iso(uint32_t ep, uint32_t packet_size, int mult, void (*cb)(transfer_t *))
+{
+	if (mult < 1 || mult > 3) return;
+	uint32_t config = (packet_size << 16) | (mult << 30);
+	if (ep < 2 || ep > NUM_ENDPOINTS) return;
+	usb_endpoint_config(endpoint_queue_head + ep * 2, config, cb);
+	if (cb) endpointN_notify_mask |= (1 << ep);
+}
+
+void usb_config_tx_iso(uint32_t ep, uint32_t packet_size, int mult, void (*cb)(transfer_t *))
+{
+	if (mult < 1 || mult > 3) return;
+	uint32_t config = (packet_size << 16) | (mult << 30);
+	if (ep < 2 || ep > NUM_ENDPOINTS) return;
+	usb_endpoint_config(endpoint_queue_head + ep * 2 + 1, config, cb);
+	if (cb) endpointN_notify_mask |= (1 << (ep + 16));
+}
+
 
 
 void usb_prepare_transfer(transfer_t *transfer, const void *data, uint32_t len, uint32_t param)

teensy4/usb_audio.cpp

 
 #include <Arduino.h>
 #include "usb_dev.h"
+#include "usb_audio.h"
 #include "debug/printf.h"
 
 #ifdef AUDIO_INTERFACE
 
-// Uncomment this to work around a limitation in Macintosh adaptive rates
-// This is not a perfect solution.  Details here:
-// https://forum.pjrc.com/threads/34855-Distorted-audio-when-using-USB-input-on-Teensy-3-1
-//#define MACOSX_ADAPTIVE_LIMIT
-
 bool AudioInputUSB::update_responsibility;
 audio_block_t * AudioInputUSB::incoming_left;
 audio_block_t * AudioInputUSB::incoming_right;
 static void rx_event(transfer_t *t);
 
 static transfer_t rx_transfer __attribute__ ((used, aligned(32)));
-/*DMAMEM*/ static uint8_t rx_buffer[AUDIO_RX_SIZE_12] __attribute__ ((aligned(32)));
-static uint16_t rx_max_size;
+DMAMEM static uint8_t rx_buffer[AUDIO_RX_SIZE] __attribute__ ((aligned(32)));
 
 //#define DMABUFATTR __attribute__ ((section(".dmabuffers"), aligned (4)))
 //uint16_t usb_audio_receive_buffer[AUDIO_RX_SIZE/2] DMABUFATTR;
 
 static void rx_queue_transfer(void)
 {
-	usb_prepare_transfer(&rx_transfer, rx_buffer, rx_max_size, 0);
-	arm_dcache_delete(&rx_transfer, rx_max_size);
+	usb_prepare_transfer(&rx_transfer, rx_buffer, AUDIO_RX_SIZE, 0);
+	arm_dcache_delete(&rx_transfer, AUDIO_RX_SIZE);
 	usb_receive(AUDIO_RX_ENDPOINT, &rx_transfer);
 }
 
-
 void usb_audio_configure(void)
 {
 	printf("usb_audio_configure\n");
 	memset(&rx_transfer, 0, sizeof(rx_transfer));
-	rx_max_size = usb_high_speed ? AUDIO_RX_SIZE_480 : AUDIO_RX_SIZE_12;
-	usb_config_rx(AUDIO_RX_ENDPOINT, rx_max_size, 0, rx_event);
+	usb_config_rx_iso(AUDIO_RX_ENDPOINT, AUDIO_RX_SIZE, 1, rx_event);
 	rx_queue_transfer();
 }
 
-
-
 void AudioInputUSB::begin(void)
 {
 	incoming_count = 0;
 	}
 }
 
+// Called from the USB interrupt when an isochronous packet arrives
+// we must completely remove it from the receive buffer before returning
+//
 static void rx_event(transfer_t *t)
 {
-	int len = rx_max_size - ((t->status >> 16) & 0x7FFF);
-	printf("rx event, len=%d\n", len);
+	unsigned int len = AUDIO_RX_SIZE - ((t->status >> 16) & 0x7FFF);
+	//int len = AUDIO_RX_SIZE - ((rx_transfer.status >> 16) & 0x7FFF);
+	printf("rx %u\n", len);
 	// TODO: actually move the data from USB to audio lib
+	usb_audio_receive_callback(len);
 	rx_queue_transfer();
 }
 
-// Called from the USB interrupt when an isochronous packet arrives
-// we must completely remove it from the receive buffer before returning
-//
-#if 0
+#if 1
 void usb_audio_receive_callback(unsigned int len)
 {
 	unsigned int count, avail;
 
 	AudioInputUSB::receive_flag = 1;
 	len >>= 2; // 1 sample = 4 bytes: 2 left, 2 right
-	data = (const uint32_t *)usb_audio_receive_buffer;
+	data = (const uint32_t *)rx_buffer;
 
 	count = AudioInputUSB::incoming_count;
 	left = AudioInputUSB::incoming_left;

teensy4/usb_desc.c

 	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
 	AUDIO_TX_ENDPOINT | 0x80,		// bEndpointAddress
 	0x09, 					// bmAttributes = isochronous, adaptive
-	LSB(AUDIO_TX_SIZE_480), MSB(AUDIO_TX_SIZE_480),	// wMaxPacketSize
-	1,			 		// bInterval, 1 = every frame
+	LSB(AUDIO_TX_SIZE), MSB(AUDIO_TX_SIZE),	// wMaxPacketSize
+	4,			 		// bInterval, 4 = every 8 micro-frames
 	0,					// bRefresh
 	0,					// bSynchAddress
 	// Class-Specific AS Isochronous Audio Data Endpoint Descriptor
 	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
 	AUDIO_RX_ENDPOINT,			// bEndpointAddress
 	0x05, 					// bmAttributes = isochronous, asynchronous
-	LSB(AUDIO_RX_SIZE_480), MSB(AUDIO_RX_SIZE_480),	// wMaxPacketSize
-	1,			 		// bInterval, 1 = every frame
+	LSB(AUDIO_RX_SIZE), MSB(AUDIO_RX_SIZE),	// wMaxPacketSize
+	4,			 		// bInterval, 4 = every 8 micro-frames
 	0,					// bRefresh
 	AUDIO_SYNC_ENDPOINT | 0x80,		// bSynchAddress
 	// Class-Specific AS Isochronous Audio Data Endpoint Descriptor
 	AUDIO_SYNC_ENDPOINT | 0x80,		// bEndpointAddress
 	0x11, 					// bmAttributes = isochronous, feedback
 	4, 0,					// wMaxPacketSize, 4 bytes
-	1,			 		// bInterval, 1 = every frame
+	4,			 		// bInterval, 4 = 4 = every 8 micro-frames
 	5,					// bRefresh, 5 = 32ms
 	0,					// bSynchAddress
 #endif
 	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
 	AUDIO_TX_ENDPOINT | 0x80,		// bEndpointAddress
 	0x09, 					// bmAttributes = isochronous, adaptive
-	LSB(AUDIO_TX_SIZE_12), MSB(AUDIO_TX_SIZE_12),	// wMaxPacketSize
+	LSB(AUDIO_TX_SIZE), MSB(AUDIO_TX_SIZE),	// wMaxPacketSize
 	1,			 		// bInterval, 1 = every frame
 	0,					// bRefresh
 	0,					// bSynchAddress
 	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
 	AUDIO_RX_ENDPOINT,			// bEndpointAddress
 	0x05, 					// bmAttributes = isochronous, asynchronous
-	LSB(AUDIO_RX_SIZE_12), MSB(AUDIO_RX_SIZE_12),	// wMaxPacketSize
+	LSB(AUDIO_RX_SIZE), MSB(AUDIO_RX_SIZE),	// wMaxPacketSize
 	1,			 		// bInterval, 1 = every frame
 	0,					// bRefresh
 	AUDIO_SYNC_ENDPOINT | 0x80,		// bSynchAddress

teensy4/usb_desc.h

   #define SEREMU_RX_INTERVAL    2
   #define AUDIO_INTERFACE	1	// Audio (uses 3 consecutive interfaces)
   #define AUDIO_TX_ENDPOINT     3
-  #define AUDIO_TX_SIZE_12      180
-  #define AUDIO_TX_SIZE_480     24
+  #define AUDIO_TX_SIZE         180
+  //#define AUDIO_TX_SIZE_12      180
+  //#define AUDIO_TX_SIZE_480     24
   #define AUDIO_RX_ENDPOINT     3
-  #define AUDIO_RX_SIZE_12      180
-  #define AUDIO_RX_SIZE_480     24
+  #define AUDIO_RX_SIZE         180
+  //#define AUDIO_RX_SIZE_12      180
+  //#define AUDIO_RX_SIZE_480     24
   #define AUDIO_SYNC_ENDPOINT	4
   #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_INTERRUPT + ENDPOINT_TRANSMIT_INTERRUPT
   #define ENDPOINT3_CONFIG	ENDPOINT_RECEIVE_ISOCHRONOUS + ENDPOINT_TRANSMIT_ISOCHRONOUS

teensy4/usb_dev.h

 
 void usb_config_rx(uint32_t ep, uint32_t packet_size, int do_zlp, void (*cb)(transfer_t *));
 void usb_config_tx(uint32_t ep, uint32_t packet_size, int do_zlp, void (*cb)(transfer_t *));
+void usb_config_rx_iso(uint32_t ep, uint32_t packet_size, int mult, void (*cb)(transfer_t *));
+void usb_config_tx_iso(uint32_t ep, uint32_t packet_size, int mult, void (*cb)(transfer_t *));
 
 void usb_prepare_transfer(transfer_t *transfer, const void *data, uint32_t len, uint32_t param);
 void usb_transmit(int endpoint_number, transfer_t *transfer);