LPC54608: artf44835 ROM USB stack workaround

[belmontbob59]

I am using SDK 2.4.1.

rom_dev_hid_generic_bm\hid_main.c\#147 reads:

/*    WORKAROUND for artf44835 ROM driver BUG:

        Code clearing STALL bits in endpoint reset routine corrupts memory area

        next to the endpoint control data. For example When EP0, EP1_IN, EP1_OUT,

        EP2_IN are used we need to specify 3 here. But as a workaround for this

        issue specify 4. So that extra EPs control structure acts as padding buffer

        to avoid data corruption. Corruption of padding memory doesn’t affect the

        stack/program behaviour.

     */

    usb_param.max_num_ep = 2 + 1;

    usb_param.mem_base = (uint32_t)&g_memUsbStack;

    usb_param.mem_size = USB_STACK_MEM_SIZE;

I have 3 questions:

1)

I read “For example When EP0, EP1_IN, EP1_OUT, EP2_IN are used we need to specify 3 here” as the value 3 referring to the number of Logical endpoints and NOT physical endpoints. Is this correct?

assuming that the workaround refers to logical endpoints this explains that “2 + 1” because of EP0 and EP1_IN (HID).

2)

why is this workaround missing from other ROM USB Stack based examples ?

For example, rom_dev_audio_bm\sources\audio_main.c\#99 reads:

usb_param.max_num_ep = 2;

2.a) this does not mention WORKAROUND for artf44835?

2.b) The example is using EP0,EP1_IN,EP1_OUT;so shouldn't this be 2+1 as well to address artf44835?

With the discrepancy mentioned above in [2.a], is artf44835 still relevant to LPC546xx or should it be dismissed?

Thank you

[jeremyzhou]

Hi Bob,

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
1) Yes, it means the logical endpoint.
2) I think all ROM USB demo should add the corresponding workaround for artf44835 ROM driver bug, I'll contact the SDK library team for confirming, and inform you ASAP after I get some clarifications.

Have a great day,
TIC

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