Set workaround for anomaly [199] (USBD cannot receive tasks during DMA) permanently

[Jochen0x90h]

Hi!

Anomaly [199] states this workaround:

*(volatile uint32_t *)0x40027C1C = 0x00000082;

Is it ok to set it once in the initialization and therefore mermanently or is it required to set it to zero again as soon as all DMA transfers have stopped?
What is the side effect of setting it permanently?

Thanks and with kind regards,
Jochen

[Simonr]

Hi Jochen

No, you should indeed set this register to 0 again after all DMA transfers have stopped. I'm afraid I don't have much to say about the side effects of not doing so, except that undefined behavior and higher current consumption may occur. It is strongly recommended to follow the workaround instructions.

Best regards,

Simon

[Jochen0x90h]

Hi Simon,

thanks for the info. Is there a race condition, for example when I check DMA transfers and they are in progress, but stop just before I issue the next task?

[Simonr]

I'm sorry, but I don't have more details than how the function is commented in the workaround function in the SDK. This is an internal function to clear the flag informing about EasyDMA transfer pending. This function is/should always be called just after the finished EasyDMA transter. It marks that EasyDMA is free for use.

Best regards,

Simon