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Section 20 USB Function Module
Rev. 4.00 Sep. 14, 2005 Page 763 of 982
REJ09B0023-0400
Bit Bit Name
Initial
Value R/W Description
0 EP1DMAE 0 R/W Endpoint 1 DMA Transfer Enable
When this bit is set, DMA transfer is enabled from the
endpoint 1 receive FIFO buffer to memory. If there is
at least one byte of receive data in the FIFO buffer, a
transfer request is asserted for the DMA controller. In
DMA transfer, when all the received data is read, EP1
is read automatically and the completion trigger
operates.
Also, as EP1-related interrupt requests to the CPU
are not automatically masked, interrupt requests
should be masked as necessary in the interrupt
enable register.
20.3.21 USB Endpoint Stall Register (USBEPSTL)
The bits in USBEPSTL are used to forcibly stall the endpoints on the application side. While a bit
is set to 1, the corresponding endpoint returns a stall handshake to the host. The stall bit for
endpoint 0 (EP0STL) is cleared automatically on reception of 8-bit command data for which
decoding is performed in this function module. When the SETUPTS flag in USBIFR0 is set,
writing 1 to the EP0STL bit is ignored. For details, see section 20.6, Stall Operations. When
ASCE = 1 is specified, the EPxSTL bit is automatically cleared.
USBEPSTL can be initialized to H'00 by a power-on reset.
Bit Bit Name
Initial
Value R/W Description
7 to 5 All 0 R Reserved
The write value should always be 0.
4 ASCE 0 R/W Auto-Stall Clear Enable
When this bit is set to 1, the stall setting bit
(USBEPSTLR/ESxSTL) of the USB endpoint is
automatically cleared after a stall handshake is
returned to the host. This bit cannot be set for each
endpoint.
3 EP3STL 0 R/W EP3 Stall
When this bit is set to 1, endpoint 3 is placed in the
stall state.