Datasheet

4−22

4.25 Isochronous Receive Interrupt Event Register

The isochronous receive interrupt event set/clear register reflects the interrupt state of the isochronous receive

contexts. An interrupt is generated on behalf of an isochronous receive context if an INPUT_* command completes

and its interrupt bits are set to 1. Upon determining that the isochRx (bit 7) interrupt in the interrupt event register at

OHCI offset 80h/84h (see Section 4.21, Interrupt Event Register) has occurred, 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 4−19 for a complete

description of the register contents.

Type: Read/Set/Clear, Read only

Offset: A0h set register

A4h clear register (returns the contents of isochronous receive interrupt event register

bit-wise ANDed with the isochronous receive mask register when read)

Default: 0000 000Xh

Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16

Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Default 0 0 0 0 0 0 0 0 0 0 0 0 X X X X

Table 4−19. Isochronous Receive Interrupt Event Register Description

BIT FIELD NAME TYPE DESCRIPTION

31−4 RSVD R Reserved. Bits 31−4 return 0s when read.

3 isoRecv3 RSC Isochronous receive channel 3 caused the interrupt event register bit 7 (isochRx) interrupt.

2 isoRecv2 RSC Isochronous receive channel 2 caused the interrupt event register bit 7 (isochRx) interrupt.

1 isoRecv1 RSC Isochronous receive channel 1 caused the interrupt event register bit 7 (isochRx) interrupt.

0 isoRecv0 RSC Isochronous receive channel 0 caused the interrupt event register bit 7 (isochRx) interrupt.

4.26 Isochronous Receive Interrupt Mask Register

The isochronous receive interrupt mask set/clear register enables the isochRx interrupt source on a per-channel

basis. Reads from either the set register or the clear register always return the contents of the isochronous receive

interrupt mask register. In all cases, the enables for each interrupt event align with the isochronous receive interrupt

event register bits detailed in Table 4−19.