USB on-the-go full-speed (OTG_FS) RM0402
1100/1163 RM0402 Rev 6
space availability in the receive FIFO, non-isochronous OUT tokens receive a NAK
handshake response, and the core ignores isochronous OUT data packets
2. The core writes the Global OUT NAK pattern to the receive FIFO. The application must
reserve enough receive FIFO space to write this data pattern.
3. When the application pops the Global OUT NAK pattern word from the receive FIFO,
the core sets the GONAKEFF interrupt (OTG_GINTSTS).
4. Once the application detects this interrupt, it can assume that the core is in Global OUT
NAK mode. The application can clear this interrupt by clearing the SGONAK bit in
OTG_DCTL.
Application programming sequence:
1. To stop receiving any kind of data in the receive FIFO, the application must set the
Global OUT NAK bit by programming the following field:
– SGONAK = 1 in OTG_DCTL
2. Wait for the assertion of the GONAKEFF interrupt in OTG_GINTSTS. When asserted,
this interrupt indicates that the core has stopped receiving any type of data except
SETUP packets.
3. The application can receive valid OUT packets after it has set SGONAK in OTG_DCTL
and before the core asserts the GONAKEFF interrupt (OTG_GINTSTS).
4. The application can temporarily mask this interrupt by writing to the GONAKEFFM bit in
the OTG_GINTMSK register.
– GONAKEFFM = 0 in the OTG_GINTMSK register
5. Whenever the application is ready to exit the Global OUT NAK mode, it must clear the
SGONAK bit in OTG_DCTL. This also clears the GONAKEFF interrupt
(OTG_GINTSTS).
– CGONAK = 1 in OTG_DCTL
6. If the application has masked this interrupt earlier, it must be unmasked as follows:
– GONAKEFFM = 1 in OTG_GINTMSK
• Disabling an OUT endpoint
The application must use this sequence to disable an OUT endpoint that it has enabled.
Application programming sequence:
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