17
OUT Payload Greater than 64 Bytes
The CPU loads the SNDFIFO with 64 bytes of data, then writes SNDBC = 64. If SNDBAVIRQ
= 1, it can load the second portion of the data packet into the SNDFIFO, after which it again
writes the SNDBC register with the byte count. To launch the transfer it loads HXFR register
with 0110eeee.
As a FIFO becomes available, the SIE continues to assert SNDBAVIRQ, asking for the next
chunk of ISO OUT data. The double-buffering allows the SIE to send OUT data from one FIFO
while the CPU loads the other one.
The SIE terminates the ISO OUT transfer by updating the HRSLT bits and asserting the
HXFRDNIRQ. An ISO OUT transfer terminates after the SIE transmits the last byte of a FIFO
with an associated SNDBC<64, or when the CPU loads SNDBC = 0.