8−22
8.23 Isochronous Transmit Interrupt Event Register
The isochronous transmit interrupt event set/clear register reflects the interrupt state of the isochronous transmit
contexts. An interrupt is generated on behalf of an isochronous transmit context if an OUTPUT_LAST* command
completes and its interrupt bits are set to 1. Upon determining that the isochTx (bit 6) interrupt has occurred in the
interrupt event register at OHCI offset 80h/84h (see Section 8.21), software can check this register to determine which
context(s) caused the interrupt. The interrupt bits are set to 1 by an asserting edge of the corresponding interrupt
signal, or by writing a 1 in the corresponding bit in the set register. The only mechanism to clear a bit in this register
is to write a 1 to the corresponding bit in the clear register. See Table 8−17 for a complete description of the register
contents.
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Name Isochronous transmit interrupt event
Type RRRRRRRRRRRRRRRR
Default 0000000000000000
Bit 15 14 13 12 11 109876543210
Name Isochronous transmit interrupt event
Type R R R R R R R R RSC RSC RSC RSC RSC RSC RSC RSC
Default 0 0 0 0 0 0 0 0 X X X X X X X X
Register: Isochronous transmit interrupt event
Offset: 90h set register
94h clear register [returns the contents of the isochronous transmit interrupt event
register bit-wise ANDed with the isochronous transmit interrupt mask register
when read]
Type: Read/Set/Clear, Read-only
Default: 0000 00XXh
Table 8−17. Isochronous Transmit Interrupt Event Register Description
BIT FIELD NAME TYPE DESCRIPTION
31−8 RSVD R Reserved. Bits 31−8 return 0s when read.
7 isoXmit7 RSC Isochronous transmit channel 7 caused the interrupt event register bit 6 (isochTx) interrupt.
6 isoXmit6 RSC Isochronous transmit channel 6 caused the interrupt event register bit 6 (isochTx) interrupt.
5 isoXmit5 RSC Isochronous transmit channel 5 caused the interrupt event register bit 6 (isochTx) interrupt.
4 isoXmit4 RSC Isochronous transmit channel 4 caused the interrupt event register bit 6 (isochTx) interrupt.
3 isoXmit3 RSC Isochronous transmit channel 3 caused the interrupt event register bit 6 (isochTx) interrupt.
2 isoXmit2 RSC Isochronous transmit channel 2 caused the interrupt event register bit 6 (isochTx) interrupt.
1 isoXmit1 RSC Isochronous transmit channel 1 caused the interrupt event register bit 6 (isochTx) interrupt.
0 isoXmit0 RSC Isochronous transmit channel 0 caused the interrupt event register bit 6 (isochTx) interrupt.