Interrupt Servicing Flow - NEC switch User Manual

8.7.2 Interrupt servicing flow

(1) USB token packet reception interrupt servicing
INTUSBRT occurrence
Receive error occurred?
No
Receive token is OUT?
No
Yes
Receive token is
SETUP?
Receive token is
unplanned token?
No
SETUP token
reception processing
IN token reception
processing to ENDPOINT 0
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CHAPTER 8
Yes
Yes
Waiting for OUT token?
No
Yes
OUT to ENDPOINT 1?
Yes
IN token reception
to ENDPOINT 1?
OUT token reception
processing when status stage
IN or data stage IN is received
IN token reception
processing to ENDPOINT 1
RETI
User's Manual U12978EJ3V0UD
USB FUNCTION
Yes
No
Yes
OUT token reception
No
processing to ENDPOINT 1
No
Token mismatch
processing
OUT token reception
processing