Datasheet

841
SAM9G45 [DATASHEET]
Atmel-6438O-ATARM-SAM9G45-Datasheet_08-Dec-15
Figure 37-12. Autovalid with DMA
Note: In the illustration above Autovalid validates a bank as full, although this might not be the case, in order to continue processing
data and to send to DMA.
Isochronous IN
Isochronous-IN is used to transmit a stream of data whose timing is implied by the delivery rate. Isochronous
transfer provides periodic, continuous communication between host and device.
It guarantees bandwidth and low latencies appropriate for telephony, audio, video, etc.
If the endpoint is not available (TX_PK_RDY = 0), then the device does not answer to the host. An ERR_FL_ISO
interrupt is generated in the UDPHS_EPTSTAx register and once enabled, then sent to the CPU.
The STALL_SNT command bit is not used for an ISO-IN endpoint.
High Bandwidth Isochronous Endpoint Handling: IN Example
For high bandwidth isochronous endpoints, the DMA can be programmed with the number of transactions
(BUFF_LENGTH field in UDPHS_DMACONTROLx) and the system should provide the required number of
packets per microframe, otherwise, the host will notice a sequencing problem.
Bank 0
Bank 1
Bank 0Bank (usb)
Write write bank 0 write bank 1 write bank 0
Bank 0Bank (system) Bank 1 Bank 0 Bank 1
Virtual TX_PK_RDY Bank 0
Virtual TX_PK_RDY Bank 1
TX_PK_RDY
(Virtual 0 & Virtual 1)
bank 0 is full bank 1 is full bank 0 is full
IN data 0 IN data 1
IN data 0
Bank 1
Bank 1 Bank 0