ST STM32F446 Series

RM0390 Rev 4 1229/1328
RM0390 USB on-the-go full-speed/high-speed (OTG_FS/OTG_HS)
1264
Figure 418. Normal bulk/control OUT/SETUP transactions - DMA
• NAK and NYET handling with internal DMA:
1. The OTG_HS host sends a bulk OUT transaction.
2. The device responds with NAK or NYET.
3. If the application has unmasked NAK or NYET, the core generates the corresponding
interrupt(s) to the application. The application is not required to service these interrupts,
since the core takes care of rewinding the buffer pointers and re-initializing the Channel
without application intervention.
4. The core automatically issues a ping token.
5. When the device returns an ACK, the core continues with the transfer. Optionally, the
application can utilize these interrupts, in which case the NAK or NYET interrupt is
masked by the application.
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