MC68332 Datasheet, PDF (32/88 Pages) Freescale Semiconductor, Inc – 32-Bit Modular Microcontroller

Freescale Semiconductor, Inc.
CSPAR1 —Chip Select Pin Assignment Register 1
$YFFA46
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
CSPA1[4]
CSPA1[3]
CSPA1[2]
CSPA1[1]
CSPA1[0]
RESET:
0
0
0
0
0
0 DATA7 1 DATA 1 DATA 1 DATA 1 DATA 1
[7:6]
[7:5]
[7:4]
[7:3]
CSPAR1 contains five 2-bit fields that determine the functions of corresponding chip-select pins.
CSPAR1[15:10] are not used. These bits always read zero; writes have no effect.
CSPAR0 Field
CSPA1[4]
CSPA1[3]
CSPA1[2]
CSPA1[1]
CSPA1[0]
Table 14 CSPAR1 Pin Assignments
Chip Select Signal
CS10
CS9
CS8
CS7
CS6
Alternate Signal
ADDR23
ADDR22
ADDR21
ADDR20
ADDR19
Discrete Output
ECLK
PC6
PC5
PC4
PC3
At reset, either the alternate function (01) or chip-select function (11) can be encoded. DATA pins are
driven to logic level one by a weak interval pull-up during reset. Encoding is for chip-select function un-
less a data line is held low during reset. Note that bus loading can overcome the weak pull-up and hold
pins low during reset. The following table shows the hierarchical selection method that determines the
reset functions of pins controlled by CSPAR1.
Table 15 Reset Pin Function of CS[10:6]
DATA7
1
1
1
1
1
0
Data Bus Pins at Reset
DATA6 DATA5 DATA4
1
1
1
1
1
1
1
1
0
1
0
X
0
X
X
X
X
X
Chip-Select/Address Bus Pin Function
DATA3 CS10/ CS9/ CS8/ CS7/ CS6/
ADDR23 ADDR22 ADDR21 ADDR20 ADDR19
1
CS10 CS9
CS8
CS7
CS6
0
CS10 CS9
CS8
CS7 ADDR19
X
CS10 CS9
CS8 ADDR20 ADDR19
X
CS10 CS9 ADDR21 ADDR20 ADDR19
X
CS10 ADDR22 ADDR21 ADDR20 ADDR19
X ADDR23 ADDR22 ADDR21 ADDR20 ADDR19
A pin programmed as a discrete output drives an external signal to the value specified in the port C
pin data register (PORTC), with the following exceptions:
1. No discrete output function is available on pins BR, BG, or BGACK.
2. ADDR23 provides E-clock output rather than a discrete output signal.
When a pin is programmed for discrete output or alternate function, internal chip-select logic still func-
tions and can be used to generate DSACK or AVEC internally on an address match.
Port size is determined when a pin is assigned as a chip select. When a pin is assigned to an 8-bit port,
the chip select is asserted at all addresses within the block range. If a pin is assigned to a 16-bit port,
the upper/lower byte field of the option register selects the byte with which the chip select is associated.
MOTOROLA
32
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MC68332
MC68332TS/D