Datasheet
MOTOROLA MC68332
32 MC68332TS/D
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.
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.
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.
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
[7:6]
1 DATA
[7:5]
1 DATA
[7:4]
1 DATA
[7:3]
1
Table 14 CSPAR1 Pin Assignments
CSPAR0 Field Chip Select Signal Alternate Signal Discrete Output
CSPA1[4] CS10
ADDR23 ECLK
CSPA1[3] CS9
ADDR22 PC6
CSPA1[2] CS8
ADDR21 PC5
CSPA1[1] CS7
ADDR20 PC4
CSPA1[0] CS6
ADDR19 PC3
Table 15 Reset Pin Function of CS[10:6]
Data Bus Pins at Reset Chip-Select/Address Bus Pin Function
DATA7 DATA6 DATA5 DATA4 DATA3 CS10
/
ADDR23
CS9/
ADDR22
CS8/
ADDR21
CS7/
ADDR20
CS6/
ADDR19
11111CS10 CS9 CS8 CS7 CS6
11110 CS10 CS9 CS8 CS7 ADDR19
111
0 X CS10 CS9 CS8 ADDR20 ADDR19
11
0 X X CS10 CS9 ADDR21 ADDR20 ADDR19
1
0 X X X CS10 ADDR22 ADDR21 ADDR20 ADDR19
0XXXXADDR23 ADDR22 ADDR21 ADDR20 ADDR19
Fr
eescale S
emiconduct
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, I
Freescale Semiconductor, Inc.
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