Datasheet

30 MC68331TS/D
3.5.2 Pin Assignment Registers
The pin assignment registers (CSPAR0 and CSPAR1) contain pairs of bits that determine the function
of chip-select pins. The pin assignment encodings used in these registers are shown below.
CSPAR0 contains seven 2-bit fields that determine the functions of corresponding chip-select pins.
CSPAR0[15:14] are not used. These bits always read zero; writes have no effect. CSPAR0 bit 1 always
reads one; writes to CSPAR0 bit 1 have no effect.
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.
Table 12 Pin Assignment Encodings
Bit Field Description
00 Discrete Output
01 Alternate Function
10 Chip Select (8-Bit Port)
11 Chip Select (16-Bit Port)
CSPAR0 —Chip Select Pin Assignment Register 0 $YFFA44
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 CSPA0[6] CSPA0[5] CSPA0[4] CSPA0[3] CSPA0[2] CSPA0[1] CSBOOT
RESET:
0 0 DATA2 1 DATA2 1 DATA2 1 DATA1 1 DATA1 1 DATA1 1 1 DATA0
Table 13 CSPAR0 Pin Assignments
CSPAR0 Field Chip Select Signal Alternate Signal Discrete Output
CSPA0[6] CS5
FC2 PC2
CSPA0[5] CS4
FC1 PC1
CSPA0[4] CS3
FC0 PC0
CSPA0[3] CS2
BGACK —
CSPA0[2] CS1
BG —
CSPA0[1] CS0
BR —
CSBOOT
CSBOOT ——
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
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
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