Renesas H8S/2158, User Manual

Page: 228 / 929

Section 8 RAM-FIFO Unit (RFU)
Rev. 3.00 Jan 25, 2006 page 174 of 872
REJ09B0286-0300
Bit Bit Name Initial Value R/W Description
2
1
0 BUD2
BUD1
BUD0 1
1
0 R/W
R/W
R/W Boundary 2 to 0
These bits select the FIFO size and the
existence of boundary overflow.
000: 32 bytes
001: 64 bytes
010: 128 bytes
011: 256 bytes
100: 512 bytes
101: 1024 bytes
110: 2048 bytes
111: Boundary is not set
Legend:
X: Don't care
Table 8.1 shows how to make settings for BAR, RAR, WAR, and TMP.
In BAR, the bits upper than the boundary become valid depending on the number of FIFO bytes
set in the BUD2 to BUD0 bits. Since the lower bits become invalid, 0 should be written to these
bits. In RAR, WAR, and TMP, the bits lower than the boundary become valid. Since the upper bits
become invalid, 0 should be written to these bits.
Table 8.1 Valid Bits in BAR, RAR, WAR, and TMP
Number of
FIFO Bytes BAR Valid
Section
BAR Invalid
Section
(Should be
set to 0) Invalid Sections
in RAR, WAR, and TMP
(Should be set to 0,
no carry)
Valid Sections
in RAR, WAR,
and TMP
32 bytes A19 to A5 A4 A10 to A5 A4 to A0
64 bytes A19 to A6 A5 and A4 A10 to A6 A5 to A0
128 bytes A19 to A7 A6 to A4 A10 to A7 A6 to A0
256 bytes A19 to A8 A7 to A4 A10 to A8 A7 to A0
512 bytes A19 to A9 A8 to A4 A10 and A9 A8 to A0
1024 bytes A19 to A10 A9 to A4 A10 A9 to A0
2048 bytes A19 to A11 A10 to A4 — A10 to A0