isp1181 NXP Semiconductors, isp1181 Datasheet - Page 19

• Manufacturer Part Number: isp1181
• Description: Isp1181 Full-speed Universal Serial Bus Interface Device
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 08938
Product data
10.4.2 Isochronous endpoints
When reading from an OUT endpoint, reception of a short/empty packet at an OUT
token will stop the DMA operation after transferring the data bytes of this packet.
When writing to an IN endpoint, a short packet transferred at an IN token will stop the
DMA operation after all bytes have been transferred. If the number of bytes in the
buffer is zero, ISP1181 will automatically send an empty packet.
Table 10:
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A DMA transfer to/from an isochronous endpoint can be terminated by any of the
following conditions (bit names refer to the DMA Configuration Register, see
Table
Table 11:
EOT condition
EOT input
DMA Counter Register
Short packet
Empty packet
DMAEN bit in DMA
Configuration Register
EOT condition
EOT input active
DMA Counter Register zero
End-Of-Packet
•
•
•
•
An external End-Of-Transfer signal occurs on input EOT
The internal DMA Counter Register reaches zero (CNTREN = 1)
An End-Of-Packet (EOP) signal is detected
DMA operation is disabled by clearing bit DMAEN.
If short/empty packet EOT is enabled (SHORTP = 1 in DMA Configuration Register) and DMA
Counter Register is zero.
25):
Summary of EOT conditions for a bulk endpoint
Recommended EOT usage for isochronous endpoints
Rev. 04 — 30 October 2001
OUT endpoint
EOT is active
counter reaches zero
short packet is received and
transferred
empty packet is received and
transferred
DMAEN = 0
OUT endpoint
do not use
do not use
preferred
© Koninklijke Philips Electronics N.V. 2001. All rights reserved.
IN endpoint
EOT is active
counter reaches zero
counter reaches zero in the
middle of the buffer
empty packet is automatically
appended when needed
DMAEN = 0
IN endpoint
preferred
preferred
do not use
Full-speed USB interface
ISP1181
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