ST STM32F40 Series Reference Manual page 1128

RM0090
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Isochronous OUT transactions
A typical isochronous OUT operation is shown in
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The sequence of operations is as follows:
a)
b)
c)
d)
e)
f)
g)
The application is attempting to send one packet every frame (up to 1 maximum
packet size), starting with an odd frame. (transfer size = 1 024 bytes).
The periodic transmit FIFO can hold one packet (1 KB).
Periodic request queue depth = 4.
Initialize and enable channel 1. The application must set the ODDFRM bit in
OTG_FS_HCCHAR1.
Write the first packet for channel 1.
Along with the last Word write of each packet, the OTG_FS host writes an entry to
the periodic request queue.
The OTG_FS host attempts to send the OUT token in the next frame (odd).
The OTG_FS host generates the XFRC interrupt as soon as the last packet is
transmitted successfully.
In response to the XFRC interrupt, reinitialize the channel for the next transfer.
Handling non-ACK responses
Doc ID 018909 Rev 4
USB on-the-go full-speed (OTG_FS)
Figure 372. The assumptions are:
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