TMS320C55x5 plain/simple Isochronous example

Hi Christos,

What kind of application you are developing with ISOC end points. As far as I know there is no simple isoc example in the CSL.

Have you tried modifying the USB example1 to 3(CCS3) or CSL_USB_PollExample, CSL_USB_IntcExample, CSL_USB_DmaExample(CCS4) to use isoc end points?. This needs some effort and again it depends on your application.

Pratap

Hi Pratap,

There is already an application having highspeed bulk endpoints, on top of the CSL_USB_DmaExample for CCS4 and it works very well.

All CSL examples do work ok. Even the fullspeed audio class example is working here.

Yet when I tried to change the config descriptor and the relevant endpoint setup commands of the DmaExample in order to have simple isoc endpoints it does not even enumerate.

The application is a high bandwidth data reading/writing similar eg to usb audio. It is ok with bulk endpoints but due to re-transmissions that create some issues I need to investigate the isoc method.

Any hints?

Regards,

Christos

Hi Christos,

Do you have any infomation on at which point USB host-target communication is failing when you try with DmaExample.

Pratap.

Its ok,

After quite some investigation it was a malformed descriptor that created the non-enumeration.

Specifically the total number of configuration descriptor bytes wTotallength was specified different than what the actual length is.

I think there is a Murfy's law that only the silly mistakes can give you real headache  !!


It does enumerate after that.

I've started to test the isoc endpoints now, yet after some first tests, their bandwidth behaviour looks a bit weird, it fluxuates significantly and it has not the bandwidth (~20MB/sec) that the bulk endpoints had, just a 20% of it most of the times.

I've checked for the double buffering and did not found a specific flag, yet from a search in the cslVC5505 ibrary/project it looks to me that it is enabled by default, only in isoc transfers, could this be an issue for some reason?

Regards,

Christos

These are the changes that I did in CSL_USB_DmaExample in order to enumerate with isoc endpoints

Config Descriprions

========================================================================

Uint16    deviceDesc[9] = {0x0112, 0x0200, 0x0000, 0x4000, 0x0451,
                           0x9010, 0x0100, 0x0201, 0x0103};

Uint16    cfgDesc[40] = {0x0209, 0x003C, 0x0101, 0xC001, 0x0928,    // configure descriptor
                         0x0004, 0x0600, 0x0000, 0x0000,             // interface descriptor

                         0x0507, 0x0581, 0x0200, 0x0701,            //endpoint 1 IN descriptor  isoc
                         0x0105, 0x0005, 0x0102,                     //endpoint 1 OUT descriptor isoc
                         0x0507, 0x0582, 0x0200, 0x0701,            //endpoint 2 IN descriptor isoc
                         0x0205, 0x0005, 0x0102,                    //endpoint 2 OUT descriptor isoc

                         0x0507, 0x0283, 0x0200, 0x0700,             //endpoint 3 IN descriptor bulk
                         0x0305, 0x0002, 0x0002,                    //endpoint 3 OUT descriptor bulk
                         0x0507, 0x0284, 0x0200, 0x0700,             //endpoint 4 IN descriptor bulk
                         0x0405, 0x0002, 0x0002                        //endpoint 4 OUT descriptor bulk
                         };
========================================================================

Isoc Endpoints initialization commands within the main()

========================================================================

    /* Initialize the Isoc Endpoint IN 1 */
    eventMask = (CSL_USB_EVENT_RESET | CSL_USB_EVENT_EOT);
    status = USB_initEndptObj(CSL_USB0, hEpObjArray[2], CSL_USB_IN_EP1,
                              CSL_USB_ISO, CSL_USB_EP1_PACKET_SIZE_HS,
                              eventMask, NULL);
    if(status != CSL_SOK)
    {
        printFunction(1, "USB Endpoint init");
        return;
    }

    /* Initialize the Isoc Endpoint OUT 2 */
    status = USB_initEndptObj(CSL_USB0, hEpObjArray[3], CSL_USB_OUT_EP2,
                              CSL_USB_ISO, CSL_USB_EP2_PACKET_SIZE_HS,
                              CSL_USB_EVENT_EOT, NULL);
    if(status != CSL_SOK)
    {
        printFunction(1, "USB Endpoint init");
        return;
    }

========================================================================

No other changes than these.

The behaviour of the isoc endpoints though is not stable and with low bandwidth compared to the bulk endpoints.

Is there anything else that might be needed to change in the CSL_USB_DmaExample in order to work for isochronous?

Could be something in the isr interrupt handling or in the endpoint initialization?

Christos

Ok,

I'll need some help here.

Having the CSL_USB_DmaExample With the above changes and enumerating ok with isochronous highspeed endpoints.

This is what I get with usbview

=======================================================================================

Device Descriptor:
bcdUSB:             0x0200
bDeviceClass:         0x00
bDeviceSubClass:      0x00
bDeviceProtocol:      0x00
bMaxPacketSize0:      0x40 (64)
idVendor:           0x0451 (Texas Instruments)
idProduct:          0x9010
bcdDevice:          0x0100
iManufacturer:        0x01
iProduct:             0x02
iSerialNumber:        0x03
bNumConfigurations:   0x01

ConnectionStatus: DeviceConnected
Current Config Value: 0x01
Device Bus Speed:     High
Device Address:       0x02
Open Pipes:              6

Endpoint Descriptor:
bEndpointAddress:     0x81  IN
Transfer Type: Isochronous
wMaxPacketSize:     0x0200 (512)
bInterval:            0x01

Endpoint Descriptor:
bEndpointAddress:     0x01  OUT
Transfer Type: Isochronous
wMaxPacketSize:     0x0200 (512)
bInterval:            0x01

Endpoint Descriptor:
bEndpointAddress:     0x82  IN
Transfer Type: Isochronous
wMaxPacketSize:     0x0200 (512)
bInterval:            0x01

Endpoint Descriptor:
bEndpointAddress:     0x02  OUT
Transfer Type: Isochronous
wMaxPacketSize:     0x0200 (512)
bInterval:            0x01

Endpoint Descriptor:
bEndpointAddress:     0x83  IN
Transfer Type:        Bulk
wMaxPacketSize:     0x0200 (512)
bInterval:            0x00

Endpoint Descriptor:
bEndpointAddress:     0x03  OUT
Transfer Type:        Bulk
wMaxPacketSize:     0x0200 (512)
bInterval:            0x00

=======================================================================================

Exercizing the endpoints showed that there are no interrupts for IN or OUT requests in the isochronous interrupts.

Is there something that I miss in configuring the isoc endpoints?

Christos

Hi Christos,

Have you tried exercising the isoc end points in full speed mode. High speed mode audio class example in the CSL also does not work properly.

Pratap 

Hi Pratap,

The full speed isoc audio class example  does work here.

I've seen some posts mentioning that the Audio class in high speed did not produce interrupts. I expected though that this would be because of the DSP/BIOS usage.

It seems this highspeed isochronous problem is a more generic one and not only for the Audio class with DSP/BIOS.

Is there any TI opinion on this?

Christos

I've waited for a couple of weeks but there has been no TI response on this.

Iτ seems that no news is not-good-news in that case.

I would realy want to know if the C55x5 can have isochronous highspeed endpoints operating properly in the current silicon revision.

Can someone from TI shed some light here?

Christos

Hi,

Is there any help that can be given here?

This is open for so long without any TI response.

Christos