SH7280 Datasheet, PDF (1401/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 25 USB Function Module
25.9 DTC Transfer
This module allows DTC transfer for endpoints 1 and 2, excluding transfer of word and longword.
If endpoint 1 contains at least one byte of valid receive data, a DTC transfer request is issued to
endpoint 1. If there is no valid data in endpoint 2, a DTC transfer request is issued to endpoint 2.
When EP1DMAE in the USBDMA setting register is set to 1 to allow DTC transfer, 0-length data
received for endpoint 1 is ignored. When DTC transfer is set, it is unnecessary to write 1 to the
EP1 USBTRG/RDFN and EP2 USBTRG/PKTE bits. (1 must be written to the USBTRG/PKTE
bit for data that consists of the maximum number of bytes or less.) For EP1, the FIFO buffer
automatically becomes empty when all the received data is read. For EP2, the FIFO automatically
becomes full when the maximum number of bytes (64 bytes) is written to the FIFO and then the
data in the FIFO is transmitted. (See figures 25.21 and 25.24.)
25.9.1 DTC Transfer for Endpoint 1
If the received data for EP1 is transferred by DTC when the data on the currently selected FIFO
becomes empty, an equivalent processing of writing 1 to the USBTRG/RDFN bit is automatically
performed in the module. Therefore, do not write 1 to the EP1RDFN bit in USBTRG after reading
the data on one side of the FIFO. Correct operation cannot be guaranteed.
For example, if 150 bytes of data are received from the host, the equivalent processing of writing 1
to the USBTRG/RDFN bit is automatically performed internally in the three places in figure
25.21. This processing is done when the data on the currently selected FIFO becomes empty
meaning that the processing is to be automatically performed even if 64 bytes of data or less than
that are transferred.
64 bytes
64 bytes
22 bytes
RDFN
(automatically written)
RDFN
RDFN
(automatically written) (automatically written)
Figure 25.21 EP1 RDFN Operation
Rev. 1.00 Jun. 26, 2008 Page 1371 of 1692
REJ09B0393-0100