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22.8.2
DTC Transfer for Endpoint 1
When the data received at EP1 is transferred by the DTC, the USB function module automatically
performs the same processing as writing 1 to the RDFN bit in TRG if the currently selected FIFO
becomes empty. Accordingly, in DTC transfer, do not write 1 to the RDFN bit in TRG. If the user
writes 1 to the RDFN bit in DTC transfer, correct operation cannot be guaranteed.
To end the DTC transfer, write 0 to the EP1FULL bit in IFR0, after clearing the EP1DMAE bit in
DMA to 0 within the processing routine for a DTC transfer end interrupt. If this procedure is
omitted, the DTC transfer end interrupt is not cleared. To perform the DTC transfer again, in
addition to the said procedure, set the number of transfers in the DTC, set the interrupt source, and
then set the EP1DMAE bit in DMA to 1.
Figure 22.20 shows an example of receiving 150 bytes of data from the host. In this case, internal
processing which is the same as writing 1 to the RDFN bit in TRG is automatically performed
three times. This internal processing is performed when the currently selected data FIFO becomes
empty. Accordingly, this processing is automatically performed both when 64-byte data is sent
and when data less than 64 bytes is sent.
64 bytes
RDFN
(Automatically
performed)
Figure 22.20 RDFN Bit Operation for EP1
Section 22 USB Function Module (USB)
64 bytes
22 bytes
RDFN
(Automatically
performed)
Rev. 1.00 Mar. 12, 2008 Page 887 of 1178
RDFN
(Automatically
performed)
REJ09B0403-0100
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