Preliminary
Protocol Description(s)
www.ti.com
•
The following bits of HOST_TXCSR register should be set as:
–
Set the MODE bit (bit 13) to 1 to ensure the FIFO is enabled (only necessary if the FIFO is
shared with an Rx endpoint).
–
Set the DMAEN bit (bit 12) to 1 if a DMA request is required for this endpoint
–
The FRCDATATOG bit (bit 11) is ignored for isochronous transactions.
–
Set the DMAMODE bit (bit 10) to 1 when DMA is enabled.
For more details in using DMA, consult CPPI DMA section within this document.
20.3.2.4.2.2 Isochronous OUT Transfer Operation: Host Mode
The operation starts when the software writes to the FIFO and sets TXPKTRDY bit of HOST_TXCSR
(bit 0). This triggers the controller to send an OUT token followed by the first data packet from the
FIFO.
An interrupt is generated whenever a packet is sent and the software may use this interrupt to load the
next packet into the FIFO and set the TXPKTRDY bit in the HOST_TXCSR register (bit 0) in the same
way as for a Bulk Tx endpoint. As the interrupt could occur almost any time within a frame, depending
on when the host has scheduled the transaction, this may result in irregular timing of FIFO load
requests. If the data source for the endpoint is coming from some external hardware, it may be more
convenient to wait until the end of each frame before loading the FIFO as this will minimize the
requirement for additional buffering. This can be done by using the SOF_PULSE signal from the
controller to trigger the loading of the next data packet. The SOF_PULSE is generated once per
frame(/microframe). The interrupts may still be used to set the TXPKTRDY bit in HOST_TXCSR.
1794
Universal Serial Bus (USB)
SPRUGX9 – 15 April 2011
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
Страница 2: ...Preliminary 2 SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 92: ...92 Read This First SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1122: ...1122 Multichannel Audio Serial Port McASP SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1562: ...1562 Real Time Clock RTC SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1658: ...1658 Timers SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1750: ...1750 UART IrDA CIR Module SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1984: ...1984 Universal Serial Bus USB SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...