host_audio_task.h File Reference

#include "config.h"

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Defines
#define	AUDIO_AS_INTERFACE_CLASS   0x01
#define	AUDIO_AS_INTERFACE_SUB_CLASS   0x02
#define	SET_CUR   0x01
#define	CS_MUTE   0x0100
#define	PORT_A_RIGHT   0
#define	PORT_A_CPLX   1
#define	DAC_OUT   PORT_A_CPLX
#define	Dac_output_init()   (PORTA = 0x00, DDRA = 0xFF)
#define	MUTE_ON   TRUE
#define	MUTE_OFF   FALSE
#define	host_audio_set_cur(cs_mute)
Functions
void	host_audio_task_init (void)
	This function initializes the USB Host Audio application.
void	host_audio_task (void)
void	sof_action (void)
void	DAC_SendPort (U8)
Variables
volatile U8	audio_connected
volatile U8	audio_cpt_sof

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Detailed Description

This file contains the function declarations for USB Host Audio task application - Compiler: IAR EWAVR and GNU GCC for AVR

• Supported devices: AT90USB1287, AT90USB1286, AT90USB647, AT90USB646

  Author:

  Atmel Corporation: http://www.atmel.com
  Support and FAQ: http://support.atmel.no/

Definition in file host_audio_task.h.

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Define Documentation

#define AUDIO_AS_INTERFACE_CLASS   0x01

Definition at line 52 of file host_audio_task.h.

#define AUDIO_AS_INTERFACE_SUB_CLASS   0x02

Definition at line 53 of file host_audio_task.h.

#define SET_CUR   0x01

Definition at line 54 of file host_audio_task.h.

#define CS_MUTE   0x0100

Definition at line 55 of file host_audio_task.h.

#define PORT_A_RIGHT   0

Definition at line 59 of file host_audio_task.h.

#define PORT_A_CPLX   1

Definition at line 60 of file host_audio_task.h.

#define DAC_OUT   PORT_A_CPLX

Definition at line 65 of file host_audio_task.h.

 

#define Dac_output_init

(

)

(PORTA = 0x00, DDRA = 0xFF)

Definition at line 67 of file host_audio_task.h.

Referenced by host_audio_task_init().

#define MUTE_ON   TRUE

Definition at line 72 of file host_audio_task.h.

#define MUTE_OFF   FALSE

Definition at line 73 of file host_audio_task.h.

#define host_audio_set_cur

(

cs_mute

)

Value:

(data_stage[0] = cs_mute,             \
                                            usb_request.bmRequestType = USB_SETUP_SET_CLASS_INTER,     \
                                            usb_request.bRequest      = SET_CUR,  \
                                            usb_request.wValue        = CS_MUTE,  \
                                            usb_request.wIndex        = 0,        \
                                            usb_request.wLength       = 1,        \
                                            usb_request.uncomplete_read = FALSE,  \
                                            host_send_control(data_stage))

Definition at line 74 of file host_audio_task.h.

Referenced by host_audio_task().

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Function Documentation

void host_audio_task_init

(

void

)

This function initializes the USB Host Audio application.

Parameters:

none

Returns:

none

Definition at line 85 of file host_audio_task.c.

References audio_connected, Dac_output_init, Joy_init, and Leds_init.

{
   Leds_init();
   audio_connected = 0;
   Joy_init();
   
   // D/A converter output rate management
   // At 8 kHz, output should be updated every 125µs. But real-time issues may occur between both USB devices :
   // The Host send a token to the Device every millisecond, to get back a new samples frame.
   // On the Device side, this frame is loaded into endpoint every millisecond. So some frames may be missed in
   // the case where the endpoint is not yet validated while the token has been sent.
   // To decrease error cases and probability, the device sample rate has been fixed to 120µs.
   // The Host ouput rate is also set to 120µs.
   TCCR2A=0x02;         // Prescaler div8
   OCR2A=120;           // Reload value to count 8x120=960 for FOSC 8MHz =>120µS refresh rate
   TCCR2B=0x02;         // Timer 2 mode CTC
   TIMSK2|=(1<<OCIE2A); // Enable compare interrupt
   
   // D/A converter hardware configuration
   // In this case, user is free to do what he wants
   Dac_output_init();
}

void host_audio_task

(

void

)

This function manages the USB Host Audio application

Parameters:

none

Returns:

none

Definition at line 115 of file host_audio_task.c.

References AUDIO_AS_INTERFACE_CLASS, AUDIO_AS_INTERFACE_SUB_CLASS, audio_connected, audio_cpt_sof, audio_stream_empty, audio_stream_in, audio_stream_ptr_rd, audio_stream_ptr_wr, audio_stream_size, AUDIO_STREAM_SIZE, FALSE, Get_class, Get_ep_addr, Get_nb_ep, Get_nb_supported_interface, Get_subclass, Host_ack_all_errors, Host_ack_in_received, host_audio_set_cur, Host_continuous_in_mode, Host_data_length_U8, Host_enable_sof_interrupt, host_get_hwd_pipe_nb(), Host_read_byte, Host_select_pipe, Host_send_in, host_set_interface, Host_unfreeze_pipe, i, interf_audio_stream, Is_device_disconnection_event, Is_ep_addr_in, Is_host_in_received, Is_host_pipe_error, Is_host_ready, Is_host_stall, Is_joy_down, Is_new_device_connection_event, j, Led0_on, Led3_off, Led3_on, Leds_off, LOG_STR_CODE, mute, PIPE_AUDIO_IN, pipe_audio_in, and TRUE.

{
U8 i, j;

   // Audio Device Management
   // *********************
   if(Is_host_ready())
   {
      if(Is_new_device_connection_event())   // Device connection
      {
         for(i=0;i<Get_nb_supported_interface();i++)
         {
            // Audio Streaming Interface
            // Select the audio streaming interface that has an IN PIPE
            if((Get_class(i)==AUDIO_AS_INTERFACE_CLASS) && (Get_subclass(i)==AUDIO_AS_INTERFACE_SUB_CLASS) && (Get_nb_ep(i) != 0))
            {
               for (j=0 ; j<Get_nb_ep(i) ; j++)
               {
                 if (Is_ep_addr_in(Get_ep_addr(i,j)))
                 {
                   // Log in device
                   audio_connected=1;
                   audio_stream_ptr_wr = 0;
                   audio_stream_ptr_rd = 0;
                   audio_stream_empty = TRUE;
                   Led0_on();
                   Host_enable_sof_interrupt();
                   LOG_STR_CODE(log_audio_connect);
                   
                   // Select and enable ISOCHRONOUS pipe
                   pipe_audio_in = host_get_hwd_pipe_nb(Get_ep_addr(i,j));
                   Host_select_pipe(PIPE_AUDIO_IN);
                   Host_continuous_in_mode();
                   Host_unfreeze_pipe();
                   
                   // Set the Device in Mute mode
                   mute = TRUE;
                   Led3_on();   // LED3 is ON when device muted
                   host_audio_set_cur(mute);        // set device default state : muted
                   
                   // Enable alternate streaming interface
                   interf_audio_stream = i;                     // store interface number
                   host_set_interface(interf_audio_stream,1);   // enable streaming interface with "alternate 1" on Device
                   break;
                 }
               }
            }
         }
      }

      if (audio_connected)
      {
         // Check in AUDIO_PIPE_IN for incoming stream
         // ******************************************
         Host_select_pipe(PIPE_AUDIO_IN);
         
         // Error management : clear any error (time-out, CRC, etc...) and unfreeze pipe if error flag rises
         // Error flag rises after three errors. Errors can be identified in UPERRX register.
         if (Is_host_pipe_error())
         {
           Host_ack_all_errors();
           Host_unfreeze_pipe();
         }

         // Stream management
         if (Is_host_in_received() && (Is_host_stall()==FALSE))
         {
           // Pipe has received a new frame !
           Disable_interrupt();   // to avoid interrupt access to audio_stream_in[] buffer
           while ((Host_data_length_U8() != 0) && (audio_stream_ptr_wr != AUDIO_STREAM_SIZE))
           {
              audio_stream_in[audio_stream_ptr_wr] = Host_read_byte();
              audio_stream_ptr_wr++;
           }
           audio_stream_size = audio_stream_ptr_wr;
           audio_stream_empty = FALSE;
           Host_ack_in_received();  // all the pipe data has been read
           Host_send_in();
           Enable_interrupt();
         }
         
         // Mute control : toggle MUTE state with Joystick DOWN direction
         if (Is_joy_down())
         {
           audio_cpt_sof = 0;
           while (audio_cpt_sof != 10); // debounce
           if (mute == TRUE)
           {
             mute=FALSE;
             Led3_off();
           }
           else
           {
             mute=TRUE;
             Led3_on();
           }
           host_audio_set_cur(mute);
           while (Is_joy_down());
           audio_cpt_sof = 0;           // debounce
           while (audio_cpt_sof != 10);
         }
      }
   }

   // Device disconnection...
   if(Is_device_disconnection_event())
   {
      Leds_off();
      audio_stream_empty = TRUE;
      audio_stream_ptr_rd = 0;
      audio_stream_ptr_wr = 0;
      audio_stream_size = 0;
      audio_connected = 0;
   }
}

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void DAC_SendPort

(

U8

data_dac

)

Function that ouputs the 8-bits value to the R-2R ladder (2 configurations possibles) Refer to the "fig" folder that contains the schematics of the two R-2R ladder configurations

Note:

This function can also be modified to transmit the 8-bit sound sample to an external DAC (external peripheral, PWM, etc..)

Parameters:

none

Returns:

none

Definition at line 311 of file host_audio_task.c.

{
  U8   port_value;
  
  // DAC_OUT value must be set to the value specified by your external DAC ladder configuration
#if   (DAC_OUT==PORT_A_RIGHT)
  // In this configuration, see the R-2R ladder configuration on the "R2R_LADDER_RIGHT" schematic
  PORTA = data_dac;
#elif (DAC_OUT==PORT_A_CPLX)
  // In this configuration (easier to mount directly on EXPAND0 connector...), the connexions of the PORTA signals are not
  // the same that for the R2R_LADDER_RIGHT schematic. The resistor structure is the same, but the port connexions are differents :
  // see R2R_LADDER_CPLX schematic.
  port_value  = (data_dac&0x01);          // bit 0 : portA,0
  port_value |= (data_dac&0x02)<<(2-1);   // bit 1 : portA,2
  port_value |= (data_dac&0x04)<<(4-2);   // bit 2 : portA,4
  port_value |= (data_dac&0x08)<<(6-3);   // bit 3 : portA,6
  port_value |= (data_dac&0x10)<<(7-4);   // bit 4 : portA,7
  port_value |= (data_dac&0x20);          // bit 5 : portA,5
  port_value |= (data_dac&0x40)>>(6-3);   // bit 6 : portA,3
  port_value |= (data_dac&0x80)>>(7-1);   // bit 7 : portA,1
  PORTA = port_value;
#endif
}

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Variable Documentation

volatile U8 audio_connected

Definition at line 65 of file host_audio_task.c.

volatile U8 audio_cpt_sof

Definition at line 66 of file host_audio_task.c.

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