Interrupt Service Routine (ISR) Flowcharts
13-88
Figure 13–14. General USB Interrupt ISR Source Parsing Flowchart
Enter General USB
ISR
USB Device State
Changed Handler
IRQ_SRC.EP0_RX
=1?
EP0 RX
Handler
Return from General
USB ISR
Set
IRQ_SRC.
EP0_RX = 1
to clear the IT.
IRQ_SRC.EP0_TX
=1?
EP0 TX
Handler
Set
IRQ_SRC.
EP0_TX = 1
to clear the IT.
IRQ_SRC.
RXn_EOT =1?
Non-ISO RX DMA
End of Transfer
Handler
IRQ_SRC.
RXn_Cnt =1?
Non-ISO RX DMA
Transactions
Count Handler
IRQ_SRC.
TXn_Done =1?
Non-ISO TX DMA
Done Handler
The interrupt must
be cleared within the
device state changed
handler.
IRQ_SRC.Chg
=1?
Setup
Handler
DMA interrupts
are cleared within their
respective handlers.
Yes
No
No
No
Yes
No
Yes
No
Yes
No
Yes
Yes
IRQ_SRC.Setup
=1?
No
Yes
Yes
No