usb asynchronous

The terms, Asynchronous / Synchronous / Adaptive on USB audio class mean the synchronization type.
It suggests the place where the original sampling clock sits on.

- Asynchronous: the sampling clock is generated on the device side.
- Synchronous: the clock derives from USB SOF by PLL
- Adaptive: the clock is generated on the host side.

For Asynchronous Sink (output) device, like a speaker,
the device has to notify to host on its sampling clock, to synchronize the host. For this purpose, a feedback endpoint (isoc IN) is associated to the isoc OUT endpoint of the audio stream, like above QB9

For Asynchronous Source (input) device, like a microphone,
The sampling rate on the device is shown as the number of the samples in each isoc packet on the audio stream. The number is relative to the SOF frequency. Therefore, any feedback endpoint is not required.

Tsuneo

I have changed it to

* Endpoint - Standard Descriptor */
  AUDIO_STANDARD_ENDPOINT_DESC_SIZE,    /* bLength */
  USB_ENDPOINT_DESCRIPTOR_TYPE,         /* bDescriptorType */
  USB_ENDPOINT_OUT(3),                  /* bEndpointAddress */
  //USB_ENDPOINT_TYPE_ISOCHRONOUS,        /* bmAttributes */
  0x05,
  WBVAL(64),                            /* wMaxPacketSize */
  0x01,                                 /* bInterval */
  0x00,                                 /* bRefresh */
  0x00,                                 /* bSynchAddress */

and it worked, I don't understand who ever wrote the bmAttributes in Endpoint Descriptor expected it to be wrote?

/* bmAttributes in Endpoint Descriptor */
#define USB_ENDPOINT_TYPE_MASK                 0x03
#define USB_ENDPOINT_TYPE_CONTROL              0x00
#define USB_ENDPOINT_TYPE_ISOCHRONOUS          0x01
#define USB_ENDPOINT_TYPE_BULK                 0x02
#define USB_ENDPOINT_TYPE_INTERRUPT            0x03
#define USB_ENDPOINT_SYNC_MASK                 0x0C
#define USB_ENDPOINT_SYNC_NO_SYNCHRONIZATION   0x00
#define USB_ENDPOINT_SYNC_ASYNCHRONOUS         0x04
#define USB_ENDPOINT_SYNC_ADAPTIVE             0x08
#define USB_ENDPOINT_SYNC_SYNCHRONOUS          0x0C
#define USB_ENDPOINT_USAGE_MASK                0x30
#define USB_ENDPOINT_USAGE_DATA                0x00
#define USB_ENDPOINT_USAGE_FEEDBACK            0x10
#define USB_ENDPOINT_USAGE_IMPLICIT_FEEDBACK   0x20
#define USB_ENDPOINT_USAGE_RESERVED            0x30

of the keil code working

0 bLength 1 09h
1 bDescriptorType 1 05h Endpoint
2 bEndpointAddress 1 03h 3 Out
3 bmAttributes 1 05h Isochronous, Asynchronous, Data
 1..0: Transfer Type  ......01  Isochronous
 3..2: Sync Type  ....01..  Asynchronous
 5..4: Usage Type  ..00....  Data
 7..6: Reserved  00......
4 wMaxPacketSize 2 0040h 64 bytes
6 bInterval 1 01h 1 ms
7 bRefresh 1 00h
8 bSynchAddress 1 00h

Because of stuff like the above, I can not figure out how to change the isoch transfer size,bytes buffer, bytes data. I can not understand the code of the person who wrote it.

>Did you add an isoc IN endpoint for feedback?

I believe so yes?

/* Audio Input Terminal */
  AUDIO_INPUT_TERMINAL_DESC_SIZE,       /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_CONTROL_INPUT_TERMINAL,         /* bDescriptorSubtype */
  0x01,                                 /* bTerminalID */
  WBVAL(AUDIO_TERMINAL_USB_STREAMING),  /* wTerminalType */
  0x00,                                 /* bAssocTerminal */
  0x01,                                 /* bNrChannels */
  WBVAL(AUDIO_CHANNEL_M),               /* wChannelConfig */
  0x00,                                 /* iChannelNames */
  0x00,                                 /* iTerminal */
/* Audio Feature Unit */
  AUDIO_FEATURE_UNIT_DESC_SZ(1,1),      /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_CONTROL_FEATURE_UNIT,           /* bDescriptorSubtype */
  0x02,                                 /* bUnitID */
  0x01,                                 /* bSourceID */
  0x01,                                 /* bControlSize */
  AUDIO_CONTROL_MUTE |
  AUDIO_CONTROL_VOLUME,                 /* bmaControls(0) */
  0x00,                                 /* bmaControls(1) */
  0x00,                                 /* iTerminal */
/* Audio Output Terminal */
  AUDIO_OUTPUT_TERMINAL_DESC_SIZE,      /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_CONTROL_OUTPUT_TERMINAL,        /* bDescriptorSubtype */
  0x03,                                 /* bTerminalID */
  WBVAL(AUDIO_TERMINAL_SPEAKER),        /* wTerminalType */
  0x00,                                 /* bAssocTerminal */
  0x02,                                 /* bSourceID */
  0x00,                                 /* iTerminal */
/* Interface 1, Alternate Setting 0, Audio Streaming - Zero Bandwith */
  USB_INTERFACE_DESC_SIZE,              /* bLength */
  USB_INTERFACE_DESCRIPTOR_TYPE,        /* bDescriptorType */
  0x01,                                 /* bInterfaceNumber */
  0x00,                                 /* bAlternateSetting */
  0x00,                                 /* bNumEndpoints */
  USB_DEVICE_CLASS_AUDIO,               /* bInterfaceClass */
  AUDIO_SUBCLASS_AUDIOSTREAMING,        /* bInterfaceSubClass */
  AUDIO_PROTOCOL_UNDEFINED,             /* bInterfaceProtocol */
  0x00,                                 /* iInterface */
/* Interface 1, Alternate Setting 1, Audio Streaming - Operational */
  USB_INTERFACE_DESC_SIZE,              /* bLength */
  USB_INTERFACE_DESCRIPTOR_TYPE,        /* bDescriptorType */
  0x01,                                 /* bInterfaceNumber */
  0x01,                                 /* bAlternateSetting */
  0x01,                                 /* bNumEndpoints */
  USB_DEVICE_CLASS_AUDIO,               /* bInterfaceClass */
  AUDIO_SUBCLASS_AUDIOSTREAMING,        /* bInterfaceSubClass */
  AUDIO_PROTOCOL_UNDEFINED,             /* bInterfaceProtocol */
  0x00,                                 /* iInterface */
/* Audio Streaming Interface */
  AUDIO_STREAMING_INTERFACE_DESC_SIZE,  /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_STREAMING_GENERAL,              /* bDescriptorSubtype */
  0x01,                                 /* bTerminalLink */
  0x01,                                 /* bDelay */
  WBVAL(AUDIO_FORMAT_PCM),              /* wFormatTag */
/* Audio Type I Format */
  AUDIO_FORMAT_TYPE_I_DESC_SZ(1),       /* bLength */
  AUDIO_INTERFACE_DESCRIPTOR_TYPE,      /* bDescriptorType */
  AUDIO_STREAMING_FORMAT_TYPE,          /* bDescriptorSubtype */
  AUDIO_FORMAT_TYPE_I,                  /* bFormatType */
  0x01,                                 /* bNrChannels */
  0x02,                                 /* bSubFrameSize */
  16,                                   /* bBitResolution */
  0x01,                                 /* bSamFreqType */
  B3VAL(32000),                         /* tSamFreq */
/* Endpoint - Standard Descriptor */
  AUDIO_STANDARD_ENDPOINT_DESC_SIZE,    /* bLength */
  USB_ENDPOINT_DESCRIPTOR_TYPE,         /* bDescriptorType */
  USB_ENDPOINT_OUT(3),                  /* bEndpointAddress */
  //USB_ENDPOINT_TYPE_ISOCHRONOUS,        /* bmAttributes */
  0x05,
  WBVAL(64),                            /* wMaxPacketSize */
  0x04,                                 /* bInterval */
  0x00,                                 /* bRefresh */
  0x00,                                 /* bSynchAddress */

I still am not sure how to change the isoch transfer with the keil code.

But I think it is 10 * 64 = 640. I did change WBVAL(64), to WBVAL(128), but it is still only 640

Interface 1 / Alt 1     Audio, 1 pipe
Endpoint 03h    3 Out, Isochronous 128 bytes

Endpoint 03h    3 Out, Isochronous

Bytes to Transfer       280h (640)

>> Did you add an isoc IN endpoint for feedback?
> I believe so yes?

Not yet.
Add a descriptor of the feedback EP,
Modify the standard / class-specific EP descriptors.
Your Type I descriptor declares PCM of 2 bytes (16bits), single channel, 32kHz sampling.
Therefore, wMaxPacketSize of the isoc OUT EP is 66 bytes.
2 bytes * 1 ch * (32 + 1) samples = 66 bytes

/* Endpoint - Standard Descriptor */
  AUDIO_STANDARD_ENDPOINT_DESC_SIZE,    /* bLength */
  USB_ENDPOINT_DESCRIPTOR_TYPE,         /* bDescriptorType */
  USB_ENDPOINT_OUT(3),                  /* bEndpointAddress */
  //USB_ENDPOINT_TYPE_ISOCHRONOUS,        /* bmAttributes */
  0x05,                    // <----- USB_ENDPOINT_TYPE_ISOCHRONOUS | USB_ENDPOINT_SYNC_ASYNCHRONOUS
  WBVAL(64),                            /* wMaxPacketSize */ // <----- WBVAL(66)
  0x04,                                 /* bInterval */      // <----- 0x01 (every 1ms)
  0x00,                                 /* bRefresh */
  0x00,                                 /* bSynchAddress */  // <----- 0x83 (IN 3)

/* Endpoint - Audio Streaming */
  AUDIO_STREAMING_ENDPOINT_DESC_SIZE,   /* bLength */
  AUDIO_ENDPOINT_DESCRIPTOR_TYPE,       /* bDescriptorType */
  AUDIO_ENDPOINT_GENERAL,               /* bDescriptor */
  0x00,                                 /* bmAttributes */
  0x00,                                 /* bLockDelayUnits */ // <----- 0x02 (Decoded PCM samples)
  WBVAL(0x0000),                        /* wLockDelay */

/* Endpoint - Standard Descriptor */                       // <-------- additional feedback EP
  AUDIO_STANDARD_ENDPOINT_DESC_SIZE,    /* bLength */
  USB_ENDPOINT_DESCRIPTOR_TYPE,         /* bDescriptorType */
  USB_ENDPOINT_IN(3),                   /* bEndpointAddress */
  USB_ENDPOINT_TYPE_ISOCHRONOUS,        /* bmAttributes */
  WBVAL(3),                             /* wMaxPacketSize */
  0x01,                                 /* bInterval */
  0x01,                                 /* bRefresh, every 2ms */
  0x00,                                 /* bSynchAddress */

/* Terminator */
  0                                     /* bLength */
};

With this addition of the feedback EP, the wTotalLength on the Config descriptor is modified, as follows

/* Configuration 1 */
  USB_CONFIGUARTION_DESC_SIZE,          /* bLength */
  USB_CONFIGURATION_DESCRIPTOR_TYPE,    /* bDescriptorType */
  WBVAL(                                /* wTotalLength */
    USB_CONFIGUARTION_DESC_SIZE         +
    USB_INTERFACE_DESC_SIZE             +
    AUDIO_CONTROL_INTERFACE_DESC_SZ(1)  +
    AUDIO_INPUT_TERMINAL_DESC_SIZE      +
    AUDIO_FEATURE_UNIT_DESC_SZ(1,1)     +
    AUDIO_OUTPUT_TERMINAL_DESC_SIZE     +
    USB_INTERFACE_DESC_SIZE             +
    USB_INTERFACE_DESC_SIZE             +
    AUDIO_STREAMING_INTERFACE_DESC_SIZE +
    AUDIO_FORMAT_TYPE_I_DESC_SZ(1)      +
    AUDIO_STANDARD_ENDPOINT_DESC_SIZE   +
    AUDIO_STREAMING_ENDPOINT_DESC_SIZE  +              // <----------
    AUDIO_STANDARD_ENDPOINT_DESC_SIZE                  // <----------
  ),

The feedback endpoint is supplied with the frequency ratio (master sampling / SOF frequency) in 10.10 fixed-point format on 3 bytes (left-justified, ie. 10.14 format).

In this example, 32kHz master clock derives from PCLK, divided by (VPB_CLOCK/DATA_FREQ) at Timer0.
To generate feedback value,
- Run another timer on PCLK in free run
- At USB_SOF_Event() (usbuser.c),
- - read this timer count.
- - Calculate this value
((current_timer_count - last_timer_count) << 14) / (VPB_CLOCK / DATA_FREQ)
- - Write the LSB 3 bytes of this calculated value (LSB first) into the IN 3 EP, using USB_WriteEP()
- - Save current_timer_count into last_timer_count

Tsuneo

>- Run another timer on PCLK in free run

Is this what you mean by free run, just leaving it blank? What is this (VPB_CLOCK) you talk of.

void TIMER1_IRQHandler(void)
{

LPC_TIM1->IR = 1;                         /* Clear Interrupt Flag */




LPC_SC->PCONP |= 1 << 2;     // Power on Timer'

  LPC_TIM1->MR0 = pclk/DATA_FREQ - 1;   /* TC0 Match Value 0 */
  LPC_TIM1->MCR = 3;                                    /* TCO Interrupt and Reset on MR0 */
  LPC_TIM1->TCR = 1;                                    /* TC0 Enable */
  NVIC_EnableIRQ(TIMER0_IRQn);


   }

>- At USB_SOF_Event() (usbuser.c),
> - - read this timer count.
> - - Calculate this value

I have been goolge but have not found out how to do this yet, I had a go at it.

uint32_t current_timer_count

uint32_t last_timer_count

#if USB_SOF_EVENT
void USB_SOF_Event (void) {
#if TIMER1_IRQHandler > 0
current_timer_count = TIMER1
else if
current_timer_count = TIMER1
TIMER1 = last_timer_count

#if USB_SOF_EVENT
void USB_SOF_Event (void) {
#if TIMER1_IRQHandler > 0
current_timer_count = TIMER1
else if
#if TIMER1_IRQHandler < 1000
TIMER1 = last_timer_count

LPC_TIM1->MR0 =  1000;

Unsure about LSB but is this close or not

#if USB_SOF_EVENT
void USB_SOF_Event (void) {
#if USB_DMA == 1


>Calculate this value, Write the LSB 3 bytes of this calculated value (LSB first) into the IN 3 EP, using USB_WriteEP()
if (USB_WriteEP(0x83,((current_timer_count - last_timer_count) << 14) / pclk/DATA_FREQ - 1;

> - - Save current_timer_count into last_timer_count

current_timer_count = last_timer_count


LPC_USB->USBDMARSet = 1 << EPAdr(0x83);

I put timer counter in main.c like this

void TIMER1_IRQHandler(void)
{

if TIMER1_IRQHandler > 0
current_timer_count = TIMER1
else if TIMER1_IRQHandler < 1000
TIMER1 = last_timer_count


LPC_TIM1->IR = 1;                         /* Clear Interrupt Flag */




  LPC_SC->PCONP |= 1 << 2;     // Power on Timer'

  LPC_TIM1->MR0 =  1000; // 1us


  LPC_TIM1->MCR = 3;                                    /* TCO Interrupt and Reset on MR0 */
  LPC_TIM1->TCR = 1;                                    /* TC0 Enable */
  NVIC_EnableIRQ(TIMER0_IRQn);

In above post, I've missed to pick up this mods to the streaming interface descriptor.

/* Interface 1, Alternate Setting 1, Audio Streaming - Operational */
  USB_INTERFACE_DESC_SIZE,              /* bLength */
  USB_INTERFACE_DESCRIPTOR_TYPE,        /* bDescriptorType */
  0x01,                                 /* bInterfaceNumber */
  0x01,                                 /* bAlternateSetting */
  0x01,                                 /* bNumEndpoints */    <----- 0x02 (plus one, for the feedback EP)
  USB_DEVICE_CLASS_AUDIO,               /* bInterfaceClass */
  AUDIO_SUBCLASS_AUDIOSTREAMING,        /* bInterfaceSubClass */
  AUDIO_PROTOCOL_UNDEFINED,             /* bInterfaceProtocol */
  0x00,                                 /* iInterface */

>> - Run another timer on PCLK in free run
> Is this what you mean by free run, just leaving it blank? What is this (VPB_CLOCK) you talk of.

Just enable the Timer1 on the default setting. No interrupt is required for the Timer1

current_timer_count is a readout of Timer1 register (T1TC), at the entry of USB_SOF_Event() callback.
It represents the SOF timing measured on the PCLK, which is also the master sampling clock for DAC.
Unfortunately, USB engines on LPC family don't have hardware SOF trigger to Timers. As a workaround, the timer value at the SOF timing is captured by the firmware at SOF (FRAME) interrupt.

> if (USB_WriteEP(0x83,((current_timer_count - last_timer_count) << 14) / pclk/DATA_FREQ - 1;

"- 1" is not required.
The example sets up Timer0 match register with "VPB_CLOCK/DATA_FREQ - 1"

demo.c
int main(void)
{
  ...
  /* Setup Timer Counter 0: Periodic Timer with Interrupt at DATA_FREQ Rate */
  T0MR0 = VPB_CLOCK/DATA_FREQ - 1;          /* TC0 Match Value 0 */

It's because the full-count of the timer is less than the total count by one
For the calculation of feedback value, the total count (VPB_CLOCK/DATA_FREQ) is applied.
Also, round bracket is recommended around (pclk/DATA_FREQ), to control the calculation order.

Tsuneo

Ah, the second parameter of USB_WriteEP() takes a buffer, not a value.

uint32_t feedback_value;
feedback_value = ((current_timer_count - last_timer_count) << 14) / (VPB_CLOCK/DATA_FREQ);
USB_WriteEP( 0x83, &feedback_value, 3 );

Tsuneo

>current_timer_count - last_timer_count

You have not explain why you have wrote this, I not sure how to read Timer and the examples don't have any values like the above, so if you could explain more it would help. Was the main.c I wrote correct of wrong?

On the startup section of the main(), just enable Timer1 on the default setting.

demo.c

/* Main Program */

int main (void) {
  ...
  ...
  /* Setup Timer Counter 0 Interrupt */
  VICVectAddr4 = (unsigned long)tc0_isr;    /* TC0 Interrupt -> Vector 4   */
  VICVectCntl4 = 0x02;                      /* TC0 Interrupt -> Priority 2 */
  VICIntEnable = 1 << 4;                    /* Enable TC0 Interrupt */

  /* Setup Timer1 for rate feedback */
  T1TCR = 1;                                /* TC1 Enable */

  lcd_init();
  ...

Here is mods for USB_SOF_Event(). For rate feedback, the extra code (in red) is inserted

usbuser.c

/*
 *  USB Start of Frame Event Callback
 *   Called automatically on USB Start of Frame Event
 */

DWORD last_timer_count;

#if USB_SOF_EVENT
void USB_SOF_Event (void) {
  DWORD current_timer_count;
  DWORD feedback_value;
                                                // feedback
  current_timer_count = T1TC;                   // capture current SOF timing on the Timer1
  if ( USB_AltSetting[1] == 1 ) {               // When interface 1 / alt 1 is enabled,
                                                // calculate master/SOF frequency ratio in 10.10 (10.14) format
    feedback_value = ((current_timer_count - last_timer_count) << 14) / (VPB_CLOCK/DATA_FREQ);
                                                // and send it to the feedback IN EP
    USB_WriteEP( 0x83, (BYTE*)&feedback_value, 3 );
  }
  last_timer_count = current_timer_count;       // update the last SOF timing

#if USB_DMA == 0
  ...

> current_timer_count - last_timer_count

This subtraction calculates SOF interval, on the tick of PCLK

Tsuneo

My friend come down and we test with his board, but the code is different.

So we make modifaction to his code, it's working but I am not sure if I have done it yet.

Was I supposed to change the Timer to 1 here

/*
 * Timer Counter 0 Interrupt Service Routine
 *   executed each 31.25us (32kHz frequency)
 */

void TIMER1_IRQHandler(void){

if (DataRun) {                            /* Data Stream is running */
    val = DataBuf[DataOut];                 /* Get Audio Sample */
    cnt = (DataIn - DataOut) & (B_S - 1);   /* Buffer Data Count */
    if (cnt == (B_S - P_C*P_S)) {           /* Too much Data in Buffer */
      DataOut++;                            /* Skip one Sample */

Unsure about if current_timer_count = LPC_TIM1->TCR timer control register is right or not? or should it be LPC_TIM1->CCR the capture control register?

uint32_t last_timer_count;

#if USB_SOF_EVENT
void USB_SOF_Event (void) {
uint32_t current_timer_count;
  uint32_t feedback_value;
  uint32_t pclk;
                                                // feedback
  current_timer_count = LPC_TIM1->TCR;                   // capture current SOF timing on the Timer1
  if ( USB_AltSetting[1] == 1 ) {               // When interface 1 / alt 1 is enabled,
                                                // calculate master/SOF frequency ratio in 10.10 (10.14) format
    feedback_value = ((current_timer_count - last_timer_count) << 14) / (pclk/DATA_FREQ);
                                                // and send it to the feedback IN EP
    USB_WriteEP( 0x83, (uint8_t *)&feedback_value, 3 );
  }
  last_timer_count = current_timer_count;       // update the last SOF timing
#if USB_DMA == 0

LPC_TIM1->MR0 = pclk/DATA_FREQ;   /* TC0 Match Value 0 */
  LPC_TIM1->MCR = 3;                                    /* TCO Interrupt and Reset on MR0 */
  LPC_TIM1->TCR = 1;                                    /* TC0 Enable */
  NVIC_EnableIRQ(TIMER1_IRQn);

/* Setup Timer1 for rate feedback */
  //T1TCR = 1;                                /* TC1 Enable */
  LPC_SC->PCONP |= 1 << 2;     // Power on Timer'
  //LPC_TIM1->TCR = 1;

Ok thanks for any help as I say code is different to my board.

We can not figure out how to increase the isoch tranfer size it's still 640, have to do all manaul with his board no easy configwizard

/* Audio Definitions */
#define DATA_FREQ 32000                 /* Audio Data Frequency */
#define P_S       32                    /* Packet Size */
#if USB_DMA
#define P_C       4                     /* Packet Count */
#else
#define P_C       1                     /* Packet Count */
#endif
#define B_S       (8*P_C*P_S)           /* Buffer Size */

/* USB RAM Definitions */
#define USB_RAM_ADR     0x20080000  /* USB RAM Start Address */
#define USB_RAM_SZ      0x00004000  /* USB RAM Size (4kB) */

/* DMA Endpoint Descriptors */
#define DD_NISO_CNT             16  /* Non-Iso EP DMA Descr. Count (max. 32) */
#define DD_ISO_CNT               8  /* Iso EP DMA Descriptor Count (max. 32) */
#define DD_NISO_SZ    (DD_NISO_CNT * 16)    /* Non-Iso DMA Descr. Size */
#define DD_ISO_SZ     (DD_ISO_CNT  * 20)    /* Iso DMA Descriptor Size */
#define DD_NISO_ADR   (USB_RAM_ADR + 128)   /* Non-Iso DMA Descr. Address */
#define DD_ISO_ADR    (DD_NISO_ADR + DD_NISO_SZ) /* Iso DMA Descr. Address */
#define DD_SZ                 (128 + DD_NISO_SZ + DD_ISO_SZ) /* Descr. Size */

/* DMA Buffer Memory Definitions */
#define DMA_BUF_ADR   (USB_RAM_ADR + DD_SZ) /* DMA Buffer Start Address */
#define DMA_BUF_SZ    (USB_RAM_SZ  - DD_SZ) /* DMA Buffer Size */

#if USB_DMA




#pragma arm section zidata = "USB_RAM"
uint32_t UDCA[USB_EP_NUM];                     /* UDCA in USB RAM */




uint32_t DD_NISO_Mem[4*DD_NISO_CNT];           /* Non-Iso DMA Descriptor Memory */
uint32_t DD_ISO_Mem [5*DD_ISO_CNT];            /* Iso DMA Descriptor Memory */
#pragma arm section zidata
uint32_t udca[USB_EP_NUM];                     /* UDCA saved values */




uint32_t DDMemMap[2];                          /* DMA Descriptor Memory Usage */




#endif

#if USB_DMA
uint32_t *InfoBuf = (uint32_t *)(DMA_BUF_ADR);
short *DataBuf = (short *)(DMA_BUF_ADR + 4*P_C);
#else
uint32_t InfoBuf[P_C];
short DataBuf[B_S];                         /* Data Buffer */
#endif

Not sure where to make the modification here, am I limited to a 640 transfer? ok thanks.

I check and it was TCR timer control register I needed so the above posted post code above was right then?