Errata nRF52840 - USBD: USBD cannot receive tasks during DMA

This anomaly applies to Revision 2, build codes CKAA-Dx0, QIAA-Dx0.

It was inherited from the previous IC revision Engineering D.

Symptoms

The USBD does not perform incoming tasks.

The USBD is performing a DMA transfer.

If any EasyDMA transfer is in progress, USB tasks cannot be used.

To enable incoming tasks when using DMA, use the following code when starting a DMA transfer:


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

After the DMA transfer is completed, use:


*(volatile uint32_t *)0x40027C1C = 0x00000000;