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How to enable and use DMA for USB bulk IN endpoints

Hi,

I'm using uVision 4 with the MCB2300 development board. I'm developing a software that periodically transmits data (status information) from the device to the host (as first step, the data are sent without being explicitly requested by the host as soon as a connection has been established). Thereto I've modified the USBCDC example included with uVision. The software transmits 20 bytes periodically, using USB_WriteEP (in usbhw.c, which uses the register interface). This works fine so far. Now I would like to use the DMA engine to avoid copying the bytes word by word into the register. I've enabled DMA in the USB configuration for logical IN endpoint 2 (physical endpoint 5 which is called CDC_DEP_IN in the example), and I have managed to set up DMA descriptors. But how do I trigger a DMA transfer?
I've tried several combinations of USB_DMA_Setup and USB_DMA_Enable. Manually setting the appropriate bit in DMA_REQ_SET to trigger the interrupt results in an error state. What am I doing wrong?
Could anyone please give me some hints concerning USB DMA? Thanks a lot.
I'll be back in January, after my Christmas vacation. I wish everybody a merry Christmas and a happy new year!

Parents

0 Ola Melzig over 14 years ago in reply to Ola Melzig

voila it's WORKING Tsuneo.... I kicked all the stuff out of the endpoint isr and it works with 300Byte..

I made a small test example with 256 bytes so that I have to add a ZLP - but it still fails....I can't see anything with my software usb sniffer...

void SendDataToHost()
{
  USB_DMA_DESCRIPTOR DD;
  DD.BufAdr  = (unsigned int)pStartBufAddr;  /* DMA Buffer Address */
  DD.BufLen  = 256;                       /* DMA Packet-size */
  DD.MaxSize = 64;                        /* 64Byte for bulk-transfer */

  //DD.Cfg.Type.IsoEP = 0;
  //DD.Cfg.Type.ATLE = 0;
  DD.Cfg.Val = 0;                         /* Initial DMA Configuration */
  USB_DMA_Setup (CDC_DEP_IN, &DD);             /* Setup DMA */


  /* ************* ZLP **********/

  DD.BufLen  = 0;
  DD.MaxSize = 0;

  //DD.Cfg.Type.Link = 1;   ????
  DD.Cfg.Val = 0;
  USB_DMA_Setup (CDC_DEP_IN, &DD);

  USB_DMA_Enable(CDC_DEP_IN);                  /* Enable DMA */
  LPC_USB->USBDMARSet = 1 << EPAdr(CDC_DEP_IN);
}

My endpoint ISR is still empty. It seems that the ZLP is not yet recognized.... What does the DD.Cfg.Type.Link stand for???

Reply

0 Ola Melzig over 14 years ago in reply to Ola Melzig

voila it's WORKING Tsuneo.... I kicked all the stuff out of the endpoint isr and it works with 300Byte..

I made a small test example with 256 bytes so that I have to add a ZLP - but it still fails....I can't see anything with my software usb sniffer...

void SendDataToHost()
{
  USB_DMA_DESCRIPTOR DD;
  DD.BufAdr  = (unsigned int)pStartBufAddr;  /* DMA Buffer Address */
  DD.BufLen  = 256;                       /* DMA Packet-size */
  DD.MaxSize = 64;                        /* 64Byte for bulk-transfer */

  //DD.Cfg.Type.IsoEP = 0;
  //DD.Cfg.Type.ATLE = 0;
  DD.Cfg.Val = 0;                         /* Initial DMA Configuration */
  USB_DMA_Setup (CDC_DEP_IN, &DD);             /* Setup DMA */


  /* ************* ZLP **********/

  DD.BufLen  = 0;
  DD.MaxSize = 0;

  //DD.Cfg.Type.Link = 1;   ????
  DD.Cfg.Val = 0;
  USB_DMA_Setup (CDC_DEP_IN, &DD);

  USB_DMA_Enable(CDC_DEP_IN);                  /* Enable DMA */
  LPC_USB->USBDMARSet = 1 << EPAdr(CDC_DEP_IN);
}

My endpoint ISR is still empty. It seems that the ZLP is not yet recognized.... What does the DD.Cfg.Type.Link stand for???

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