Add volume/mute feature to AudioInputUSB

Change descriptor and code to handle features for USB Audio

teensy3/usb_audio.cpp

 uint16_t AudioInputUSB::incoming_count;
 uint8_t AudioInputUSB::receive_flag;
 
+struct usb_audio_features_struct AudioInputUSB::features = {0,0,FEATURE_MAX_VOLUME};
+
 #define DMABUFATTR __attribute__ ((section(".dmabuffers"), aligned (4)))
 uint16_t usb_audio_receive_buffer[AUDIO_RX_SIZE/2] DMABUFATTR;
 uint32_t usb_audio_sync_feedback DMABUFATTR;
 	return target * 4;
 }
 
+int usb_audio_get_feature(void *stp, uint8_t *data, uint32_t *datalen)
+{
+	struct setup_struct setup = *((struct setup_struct *)stp);
+	if (setup.bmRequestType==0xA1) { // should check bRequest too, and UnitID
+		if (setup.bChannel==0) { // only support main, but in theory could do left/right as well
+			if (setup.bCS==0x01) { // mute
+				data[0] = AudioInputUSB::features.mute;  // 1=mute, 0=unmute
+				*datalen = 1;
+				return 1;
+			}
+			else if (setup.bCS==0x02) { // volume
+				if (setup.bRequest==0x81) { // GET_CURR
+					data[0] = AudioInputUSB::features.volume & 0xFF;
+					data[1] = (AudioInputUSB::features.volume>>8) & 0xFF;
+				}
+				else if (setup.bRequest==0x82) { // GET_MIN
+					//serial_print("vol get_min\n");
+					data[0] = 0;     // min level is 0
+					data[1] = 0;
+				}
+				else if (setup.bRequest==0x83) { // GET_MAX
+					data[0] = FEATURE_MAX_VOLUME & 0xFF;  // max level, for range of 0 to MAX
+					data[1] = (FEATURE_MAX_VOLUME>>8) & 0x0F;
+				}
+				else if (setup.bRequest==0x84) { // GET_RES
+					data[0] = 1; // increment vol by by 1
+					data[1] = 0;
+				}
+				else { // pass over SET_MEM, etc.
+					return 0;
+				}
+				*datalen = 2;
+				return 1;
+			}
+		}
+		return 0;
+	}
+	return 0;
+}
+
+int usb_audio_set_feature(void *stp, uint8_t *buf) 
+{
+	struct setup_struct setup = *((struct setup_struct *)stp);
+	if (setup.bmRequestType==0x21) { // should check bRequest too, and UnitID
+		if (setup.bChannel==0) { 
+			if (setup.bCS==0x01) { // mute
+				if (setup.bRequest==0x01) { // SET_CUR
+					AudioInputUSB::features.mute = buf[0]; // 1=mute,0=unmute
+					AudioInputUSB::features.change = 1;
+					return 1;
+				}
+			}
+			else if (setup.bCS==0x02) { // volume
+				if (setup.bRequest==0x01) { // SET_CUR
+					AudioInputUSB::features.volume = buf[0] + (buf[1]<<8);
+					AudioInputUSB::features.change = 1;
+					return 1;
+				}
+			}
+		}
+	}
+	return 0;
+}
+
 
 #endif // F_CPU
 #endif // AUDIO_INTERFACE

teensy3/usb_audio.h

 #include "usb_desc.h"
 #ifdef AUDIO_INTERFACE
 
+#define FEATURE_MAX_VOLUME 0xFFF  // volume accepted from 0 to 0xFFF
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 extern uint16_t usb_audio_transmit_buffer[];
 extern void usb_audio_receive_callback(unsigned int len);
 extern unsigned int usb_audio_transmit_callback(void);
+int usb_audio_set_feature(void *stp, uint8_t *buf);
+int usb_audio_get_feature(void *stp, uint8_t *data, uint32_t *datalen);
+
 extern uint32_t usb_audio_sync_feedback;
 extern uint8_t usb_audio_receive_setting;
 extern uint8_t usb_audio_transmit_setting;
 #ifdef __cplusplus
 }
 
+// setup struct definition could be moved from usb_dev.c to usb_dev.h so we can reuse 
+// it instead of redefining it here
+struct setup_struct {
+  union {
+    struct {
+	uint8_t bmRequestType;
+	uint8_t bRequest;
+	union {
+		struct {
+			uint8_t bChannel;  // 0=main, 1=left, 2=right
+			uint8_t bCS;       // Control Selector
+		};
+		uint16_t wValue;
+	};
+	union {
+		struct {
+			uint8_t bIfEp;     // type of entity
+			uint8_t bEntityId; // UnitID, TerminalID, etc.
+		};
+		uint16_t wIndex;
+	};
+	uint16_t wLength;
+    };
+  };
+};
+
+// audio features supported
+struct usb_audio_features_struct {
+  int change;  // set to 1 when any value is changed
+  int mute;    // 1=mute, 0=unmute
+  int volume;  // volume from 0 to FEATURE_MAX_VOLUME, maybe should be float from 0.0 to 1.0
+};
+
 #include "AudioStream.h"
 
 class AudioInputUSB : public AudioStream
 	virtual void update(void);
 	void begin(void);
 	friend void usb_audio_receive_callback(unsigned int len);
+	friend int usb_audio_set_feature(void *stp, uint8_t *buf);
+	friend int usb_audio_get_feature(void *stp, uint8_t *data, uint32_t *datalen);
+
+	static struct usb_audio_features_struct features;
+
 private:
 	static bool update_responsibility;
 	static audio_block_t *incoming_left;

teensy3/usb_desc.c

 
 #define AUDIO_INTERFACE_DESC_POS	KEYMEDIA_INTERFACE_DESC_POS+KEYMEDIA_INTERFACE_DESC_SIZE
 #ifdef  AUDIO_INTERFACE
-#define AUDIO_INTERFACE_DESC_SIZE	9+10+12+9+12+9 + 9+9+7+11+9+7 + 9+9+7+11+9+7+9
+#define AUDIO_INTERFACE_DESC_SIZE	9+10+12+9+12+10+9 + 9+9+7+11+9+7 + 9+9+7+11+9+7+9
 #else
 #define AUDIO_INTERFACE_DESC_SIZE	0
 #endif
 	0x03, 0x00,				// wChannelConfig, 0x0003 = Left & Right Front
 	0,					// iChannelNames
 	0, 					// iTerminal
+	// Volume feature descriptor
+	10,					// bLength
+	0x24, 				// bDescriptorType = CS_INTERFACE
+	0x06, 				// bDescriptorSubType = FEATURE_UNIT
+	0x31, 				// bUnitID
+	0x03, 				// bSourceID (Input Terminal)
+	0x01, 				// bControlSize (each channel is 1 byte, 3 channels)
+	0x03, 				// bmaControls(0) Master: Volume & Mute
+	0x00, 				// bmaControls(1) Left: None
+	0x00, 				// bmaControls(2) Right: None
+	0x00,				// iFeature
 	// Output Terminal Descriptor
 	// USB DCD for Audio Devices 1.0, Table 4-4, page 40
 	9,					// bLength
 	//0x02, 0x03,				// wTerminalType, 0x0302 = Headphones
 	0x02, 0x06,				// wTerminalType, 0x0602 = Digital Audio
 	0,					// bAssocTerminal, 0 = unidirectional
-	3,					// bCSourceID, connected to input terminal, ID=3
+	0x31,				// bCSourceID, connected to feature, ID=31
 	0,					// iTerminal
 	// Standard AS Interface Descriptor
 	// USB DCD for Audio Devices 1.0, Section 4.5.1, Table 4-18, page 59

teensy3/usb_dev.c

 			return;
 		}
 		break;
-	  case 0x0122: // SET_CUR (wValue=0, wIndex=interface, wLength=len)
+	  case 0x0121: // SET FEATURE
+	  case 0x0221:
+	  case 0x0321:
+	  case 0x0421:
+	  	// handle these on the next packet. See usb_audio_set_feature()
 		return;
+	  case 0x81A1: // GET FEATURE
+	  case 0x82A1:
+	  case 0x83A1:
+	  case 0x84A1:
+	  	if (usb_audio_get_feature(&setup, reply_buffer, &datalen)) {
+	  		data = reply_buffer;
+	  	}
+	  	else {
+	  		endpoint0_stall();
+	  		return;
+	  	}
+		break;
+
 	  case 0x81A2: // GET_CUR (wValue=0, wIndex=interface, wLength=len)
 		if (setup.wLength >= 3) {
 			reply_buffer[0] = 44100 & 255;
 		}
 #endif
 #ifdef AUDIO_INTERFACE
-		if (setup.wRequestAndType == 0x0122 /* SET_CUR */) {
-			// TODO: actually check data, do something with it?
+		if (usb_audio_set_feature(&setup, buf)) {
 			endpoint0_transmit(NULL, 0);
 		}
 #endif