EZ-USB Datasheet, PDF (149/334 Pages) Cypress Semiconductor – The EZ-USB USB Integrated Circuit

Registers Associated with an ISO OUT endpoint
(EP15OUT shown as example)
Initialization
Data transfer
OUTISOVAL 15 14 13 12 11 10 9 8
Endpoint Valid (1=valid)
OUT15DATA 7 6 5 4 3 2 1 0
Data from USB
OUT15ADDR A9 A8 A7 A6 A5 A4 0 0
FIFO Start Address (see text)
USBIEN 7 6 5 4 3 2 1 0
SOFIE (1=enabled)
USBIRQ 7 6 5 4 3 2 1 0
SOFIR (1=clear request)
OUT15BCH 7 6 5 4 3 2 9 8
Received Byte Count (H)
OUT15BCL 7 6 5 4 3 2 1 0
Received Byte Count (L)
ISOERR 15 14 13 12 11 10 9 8
OUT15 CRC Error (1=error)
Figure 8-3. Isochronous OUT Registers
8.3.1 Initialization
To initialize an isochronous OUT endpoint, the 8051:
• Sets the endpoint valid bit for the endpoint.
• Sets the endpoint’s FIFO size by loading a starting address (Section 8.4, "Setting
Isochronous FIFO Sizes").
• Enables the SOF interrupt. All isochronous endpoints are serviced in response to
the SOF interrupt.
8.3.2 OUT Data Transfer
When an SOF interrupt occurs, the 8051 is presented with FIFOs containing OUT data
sent from the host in the previous frame, along with 10-bit byte counts, indicating how
many bytes are in the FIFOs. The 8051 has 1 ms to transfer data out of these FIFOs before
the next SOF interrupt arrives.
Page 8-4
Chapter 8. EZ-USB CPU
EZ-USB TRM v1.9