Section 36 USB Function Controller (USBF)
Rev. 1.00 Oct. 01, 2007 Page 1575 of 1956
REJ09B0256-0100
Figure 36.15 shows the normal operation of the USB function and firmware in isochronous-in
transfer.
EP5 has two up to 64-byte FIFOs, but the user can perform data transmission and write transmit
data without being aware of this dual-FIFO configuration.
In isochronous transfer, transfer is occurred only once per one frame (1 ms). So, when SOF is
received, the FIFO buffer is switched automatically with hardware.
FIFO buffers are switched over by the SOF reception. Therefore, the FIFO buffer in which the
USB function transmits the data and the FIFO buffer in which the firmware writes the transmit
data have different buffers, and a read and write of FIFO buffer are not competed. Accordingly,
the data written by the firmware is the data transmitted in one frame after. The buffers of FIFOs
are switched over automatically by the SOF reception, so writing of data must be completed
within the frame.
The USB function transmits data to the host, and the internal TR flag is set to 1, when data to be
transmitted to the host exists in FIFO after an in-token is received. If there is no data in the FIFO
buffer, set the internal TR flag to 1 and transmit 0-byte data to the host.
In firmware, first, the processing routine of the isochronous transfer is called by SOF interrupt to
check the time stamp. Then one packet data is written to FIFO. This written data is transmitted to
the host in the next frame.
SOF happens to be broken because of external cause during transmission from the host. In this
case, an operation flow is different from that in figure 36.15. As an example, figure 36.16 shows
the operation flow of a broken frame and a subsequent frame when SOF is broken once. When
SOF is broken, the FIFO buffer is not switched in corresponding frame, and a time out interrupt is
occurred after time set by user has been elapsed.
The firmware detects the SOF break by the time out interrupt. In this case, the FIFO buffer
connected to the CPU has the data to be transmitted in the current frame. If this data is transmitted
in the next frame, the data which is not current one is transmitted. Therefore, the firmware writes
the EP5 CPU clear (FCLR1/EP5 CCLR) to 1. When the SOF interrupt is occurred in the
subsequent frame, the processing routine of the isochronous transfer is called and the time stamps
are compared. The time stamps do not much since the SOF break occurred in the previous frame.
One packet of data is written by the firmware according to the transmitted time stamp.
In the frame in which the SOF is broken, the FIFO buffer is not switched and there in no data to be
transmitted to the host. Therefore, USB function controller transmits 0-byte data to the host. Since
the data to be transmitted is cleared by firmware, 0-byte data is transmitted to the host.
Содержание SH7763
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Страница 122: ...Section 2 Programming Model Rev 1 00 Oct 01 2007 Page 56 of 1956 REJ09B0256 0100 ...
Страница 144: ...Section 3 Instruction Set Rev 1 00 Oct 01 2007 Page 78 of 1956 REJ09B0256 0100 ...
Страница 170: ...Section 4 Pipelining Rev 1 00 Oct 01 2007 Page 104 of 1956 REJ09B0256 0100 ...
Страница 282: ...Section 7 Caches Rev 1 00 Oct 01 2007 Page 216 of 1956 REJ09B0256 0100 ...
Страница 378: ...Section 9 Interrupt Controller INTC Rev 1 00 Oct 01 2007 Page 312 of 1956 REJ09B0256 0100 ...
Страница 514: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Oct 01 2007 Page 448 of 1956 REJ09B0256 0100 ...
Страница 630: ...Section 13 PCI Controller PCIC Rev 1 00 Oct 01 2007 Page 564 of 1956 REJ09B0256 0100 ...
Страница 686: ...Section 14 Direct Memory Access Controller DMAC Rev 1 00 Oct 01 2007 Page 620 of 1956 REJ09B0256 0100 ...
Страница 710: ...Section 16 Clock Pulse Generator CPG Rev 1 00 Oct 01 2007 Page 644 of 1956 REJ09B0256 0100 ...
Страница 732: ...Section 17 Watchdog Timer and Reset WDT Rev 1 00 Oct 01 2007 Page 666 of 1956 REJ09B0256 0100 ...
Страница 752: ...Section 18 Power Down Mode Rev 1 00 Oct 01 2007 Page 686 of 1956 REJ09B0256 0100 ...
Страница 772: ...Section 19 Timer Unit TMU Rev 1 00 Oct 01 2007 Page 706 of 1956 REJ09B0256 0100 ...
Страница 824: ...Section 21 Compare Match Timer CMT Rev 1 00 Oct 01 2007 Page 758 of 1956 REJ09B0256 0100 ...
Страница 1060: ...Section 23 Gigabit Ethernet Controller GETHER Rev 1 00 Oct 01 2007 Page 994 of 1956 REJ09B0256 0100 ...
Страница 1062: ...Section 24 IP Security Accelerator SECURITY Rev 1 00 Oct 01 2007 Page 996 of 1956 REJ09B0256 0100 ...
Страница 1124: ...Section 26 I 2 C Bus Interface IIC Rev 1 00 Oct 01 2007 Page 1058 of 1956 REJ09B0256 0100 ...
Страница 1184: ...Section 27 Serial Communication Interface with FIFO SCIF Rev 1 00 Oct 01 2007 Page 1118 of 1956 REJ09B0256 0100 ...
Страница 1350: ...Section 30 SIM Card Module SIM Rev 1 00 Oct 01 2007 Page 1284 of 1956 REJ09B0256 0100 ...
Страница 1484: ...Section 33 Audio Codec Interface HAC Rev 1 00 Oct 01 2007 Page 1418 of 1956 REJ09B0256 0100 ...
Страница 1560: ...Section 35 USB Host Controller USBH Rev 1 00 Oct 01 2007 Page 1494 of 1956 REJ09B0256 0100 ...
Страница 1720: ...Section 37 LCD Controller LCDC Rev 1 00 Oct 01 2007 Page 1654 of 1956 REJ09B0256 0100 ...
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Страница 2026: ...SH7763 Hardware Manual ...