22. Serial I/O with FIFO (SIOF)
Rev.1.00 Jan. 10, 2008 Page 1121 of 1658
REJ09B0261-0100
Bit Bit Name
Initial
Value R/W Description
7 to 5 RFWM[2:0] 000 R/W Receive FIFO Watermark
000: Issue a transfer request when 1 stage or more of
the receive FIFO are valid.
001: Setting prohibited
010: Setting prohibited
011: Setting prohibited
100: Issue a transfer request when 4 or more stages of
the receive FIFO are valid.
101: Issue a transfer request when 8 or more stages of
the receive FIFO are valid.
110: Issue a transfer request when 12 or more stages
of the receive FIFO are valid.
111: Issue a transfer request when 16 stages of the
receive FIFO are valid.
A transfer request to the receive FIFO is issued by
the RDREQE bit in SISTR.
The receive FIFO is always used as 16 stages of
the FIFO regardless of these bit settings.
4 to 0 RFUA[4:0] 00000 R Receive FIFO Usable Area
These bits indicate the number of words that can be
transferred by the CPU or DMAC as B'00000 (empty) to
B'10000 (full).