Expansion Bus Registers
8-8
8.3.2
Expansion Bus Global Control Register
The expansion bus global control register (shown in Figure 8–3, and de-
scribed in Table 8–4) configures parameters of the expansion bus common to
all interfaces.
Figure 8–3. Expansion Bus Global Control Register
31
16
15
14
13
12
11
10
0
Reserved
FMOD
XFCEN
XFRAT
XARB
Reserved
R, +0
R,+x
RW,+0
RW,+00
R,+x
RW,+x
Table 8–4. Expansion Bus Global Control Register Field Description
Field
Description
FMOD
FIFO mode set by boot-mode selection.
FMOD = 0: Glue is used for FIFO read interface in all XCE spaces operating in FIFO mode
FMOD = 1: Glueless read FIFO interface. If XCE3 is selected for FIFO mode, then XOE acts
as FIFO output enable and XCE3 acts as FIFO read enable.
XOE is disabled in all other XCE
spaces regardless of MType setting.
XFCEN
FIFO clock enable
XFCEN = 0: XFCLK held high
XFCEN = 1: XFCLK enabled to clock.
The FIFO clock enable cannot be changed while a DMA request to XCE space is active.
XFRAT
FIFO clock rate
XFRAT = 00: XFCLK = 1/8 CPU clock rate
XFRAT = 01: XFCLK = 1/6 CPU clock rate
XFRAT = 10: XFCLK = 1/4 CPU clock rate
XFRAT = 11: XFCLK = 1/2 CPU clock rate
The FIFO clock setting cannot be changed while a DMA request to XCE space is active.
XARB
Arbitration mode, set by boot-mode selection
XARB=0:
internal arbiter disabled
XARB=1:
internal arbiter enabled