DMA Controller

12-70

Figure 12–48. DMA Timing When Destination is an STRB, STRB0, STRB1, MSTRB Bus
Cycles
(H1) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Rate
Source
on chip R1R2R3R4R5
Destination
STRB,
STRB0,
W1W1W1W1W2W2W2W2W3W3W3W3W4W4W4W4. . .
(1 + 2 +
C
w)
T
STRB1,
MSTRB
bus CwCwCwCw
Source
STRB,
STRB0
R1R1R1I R2R2R2I
STRB0
,
STRB1
bus CrCr(2 +
C
r + 2 +
C
w)
T
+ 0.5 (
T
– 1)
Destination
STRB
,
W1W1W1W1W2W2W2W2. . .
STRB
,
STRB0,
STRB1
bus CwCw(3.5 +
C
r + 2 +
C
w)
T
+ .5 (
T
– 1)
(’C30 only)
Source
R1R1R1R1I R2R2R2R2I R3R3R3R3I R4R4R4R4
Source
IOSTRB CrCrCrCr(3 + Cr + 2 + Cw) + (2 + Cw + max[1, Cr – Cw + 1])
(
T
1)
Destination W1W1W1W1W2W2W2W2W3W3W3W3
(
T
–1)
STRB bus CwCwCw
Legend:
T = Number of transfers W = Single-cycle writes
Cr= Source-read wait states R
n
= Multicycle reads
Cw= Destination-write wait states W
n
= Multicycle writes
R = Single-cycle reads I = Internal register cycle
Write followed by read incurs in one extra half-cycle.