TMP91C824
91C824-85
(3) Wait
control
Bits 0 to 2 (<B0W0 to B0W2>, <B1W0 to B1W2>, <B2W0 to B2W2>, <B3W0 to B3W2>,
<BEXW0 to BEXW2>) of a chip select/wait control register specify the number of waits that are to
be inserted when the corresponding memory area is accessed.
The following types of wait operation can be specified using these bits. Bit settings other than those
listed in the table should not be made.
Table 3.6.3 Wait operation settings
<BxW2 ~ BxW0> No. of Waits
Wait Operation
000 2WAIT
Inserts a wait of 2 states, irrespective of the
WAIT
pin state.
001 1WAIT
Inserts a wait of 1 state, irrespective of the
WAIT
pin state.
010 1WAIT
+
N
Samples the state of the WAIT pin after inserting a wait of one state. If the
WAIT
pin is Low, the waits continue and the bus cycle is extended until the
pin goes high.
011 0WAIT
Ends the bus cycle without a wait, regardless of the
WAIT
pin state.
100 Reserved
Invalid
setting
101 3WAIT
Inserts a wait of 3 state, irrespective of the
WAIT
pin state.
110 4WAIT
Inserts a wait of 4 state, irrespective of the
WAIT
pin state.
111 8WAIT
Inserts a wait of 8 state, irrespective of the
WAIT
pin state.
A Reset sets these bits to “000” (2 waits).
(4) Bus width and wait control for an area other than CS0 to CS3
The chip select/wait control register BEXCS controls the bus width and number of waits when
memory locations which are not in one of the four user-specified address areas (CS0 to CS3) are
accessed. The BEXCS register settings are always enabled for areas other than CS0 to CS3.
(5) Selecting 16-Mbyte area/specified address area
Setting B2CS<B2M> (bit 6 of the chip select/wait control register for CS2) to “0” designates the
16-Mbyte area 000FE0H-000FFFH, 003000H-FFFFFFH as the CS2 area. Setting B2CS<B2M> to
“1” designates the address area specified by the start address register MSAR2 and the address mask
register MAMR2 as CS2 (i.e. if B2CS<B2M> = 1, CS2 is specified in the same manner as CS0, CS1
and CS3 are).
A Reset clears this bit to “0”, specifying CS2 as a 16-M bytes address area.