4- 36
MC68341 USER’S MANUAL
MOTOROLA
Ordering Information and Mechanical Data. Section 2 Signal Descriptions shows a
block diagram of the port control circuits.
4.3.5.1 PORT A PIN ASSIGNMENT REGISTER 1 (PPARA1). PPARA1 selects between
an address and discrete I/O function for the port A pins. Any set bit defines the
corresponding pin to be an I/O pin, controlled by the port A data and data direction
registers. Any cleared bit defines the corresponding pin to be an address bit as defined in
the following register diagram. Bits set in this register override the configuration setting of
PPARA2. The $FF reset value of PPARA1 configures port A as an input port. This register
can be read or written at any time.
PPARA1
$015
76543210
PRTA7
(A31)
PRTA6
(A30)
PRTA5
(A29)
PRTA4
(A28)
PRTA3
(A27)
PRTA2
(A26)
PRTA1
(A25)
PRTA0
(A24)
RESET:
11111111
Supervisor Only
4.3.5.2 PORT A PIN ASSIGNMENT REGISTER 2 (PPARA2). PPARA2 selects between
an address and IACK≈ function for the port A pins. Any set bit defines the corresponding
pin to be an IACK≈ output pin. Any cleared bit defines the corresponding pin to be an
address bit as defined in the register diagram. Any set bits in PPARA1 override the
configuration set in PPARA2. Bit 0 has no function in this register because there is no
level 0 interrupt. This register can be read or written at any time.
PPARA2
$017
76543210
IACK7
(A31)
IACK6
(A30)
IACK5
(A29)
IACK4
(A28)
IACK3
(A27)
IACK2
(A26)
IACK1
(A25)
0
RESET:
00000000
Supervisor Only
The IACK≈ signals are asserted if a bit in PPARA2 is set and the CPU32 services an
external interrupt at the corresponding level. IACK≈ signals have the same timing as
address strobes.
4.3.5.3 PORT A DATA DIRECTION REGISTER (DDRA). DDRA controls the direction of
the pin drivers when the pins are configured as I/O. Any set bit configures the
corresponding pin as an output. Any cleared bit configures the corresponding pin as an
input. This register affects only pins configured as discrete I/O. This register can be read
or written at any time.
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Freescale Semiconductor, Inc.
For More Information On This Product,
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