XR21B1420IL28-0A Datasheet, PDF (27/60 Pages) Exar Corporation – Enhanced 1-Ch Full-Speed USB UART

XR21B1420
Table 6: Standard Interrupt Packet Format
Offset
0
1
2
4
6
8
Field
bmRequestType
bNotification
wValue
wIndex
wLength
Data
Size
(Bytes)
1
1
2
2
2
2
Value
Description
8’b1010000
1
8’h20
16’h0000
16’h0000
16’h0002
Standard
int_status
See Table 7
D7 = Device-to-host direction
D6:5 = Class Type
D4:0 = Interface Recipient
Defined encoding for SERI-
AL_STATE
D15:8 = Reserved (0)
D7:0 = Interface number, 8’h00 for
the CDC Command Interface
2 bytes of transferred data
D15-7 = Reserved (0)
D6 = bOverRun
D5 = bParity
D4 = bFraming
D3 = bRingSignal (RI)
D2 = bBreak
D1 = bTxCarrier (DSR)
D0 = bRxCarrier (CD)
Table 7: Data Field of Standard Interrupt Packet
Bit
Field
Description
D15:7
Reserved (future use)
D6
bOverRun Received data has been discarded due to over-
run in the device.
D5
bParity
A parity error has occurred.
D4
bFraming
A framing error has occurred.
D3
bRingSignal State of ring signal detection of the device.
D2
bBreak
State of break detection mechanism of the
device.
D1
bTxCarrier State of transmission carrier. This signal corre-
sponds to V.24 signal 106 and RS-232 signal
DSR.
D0
bRxCarrier State of receiver carrier detection mechanism
of device. This signal corresponds to V.24 sig-
nal 109 and RS-232 signal DCD.
If the Exar vendor specific packet mapping is enabled then the interrupt packet format is as shown in Table 8.
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