MC68340AB16E Datasheet, PDF (113/441 Pages) Motorola, Inc – Integrated Processor with DMA User’s Manual

Freescale Semiconductor, Inc.
4.2.5.2 PORT B. Port B pins can be independently programmed to function as chip
selects, IRQ≈ and MODCK pins, or discrete I/O pins. These pins are multiplexed as
shown in Figure 4-7. Selection of a pin function is accomplished by a combination of the
port B pin assignment register (PPARB) and the FIRQ bit of the MCR. See Table 4-5 for
port B combinations. By changing the value of the FIRQ bit and the corresponding bits in
the PPARB for a particular signal, the port B pins can be configured for different pin
functions. Upon reset, port B is configured as MODCK, IRQ7, IRQ6, IRQ5, IRQ3, and
CS3–CS0.
INTERRUPT
PORT
LOGIC
IRQ4/PORT B4
IRQ2/PORT B2
IRQ1/PORT B1
AVEC
CS3
CHIP-
CS2
SELECT
CS1
MODULE
CS0
MODCK/PORT B0
IRQ7/PORT B7
IRQ6/PORT B6
IRQ5/PORT B5
IRQ3/PORT B3
FULL IRQ
MUX
CS3/IRQ4/PORT B4
CS2/IRQ2/PORT B2
CS1/IRQ1/PORT B1
CS0/AVEC
FIRQ
Figure 4-7. Full Interrupt Request Multiplexer
Table 4-5. Port B Pin Assignment Register
Pin Function
Signal
FIRQ = 0
FIRQ = 0
FIRQ = 1
PPARB = 0
PPARB = 1
PPARB = 0
IRQ7
PORTB7
IRQ7
PORTB7
IRQ6
PORTB6
IRQ6
PORTB6
IRQ5
PORTB5
IRQ5
PORTB5
IRQ3
PORTB3
IRQ3
PORTB3
CS3
CS3
CS3
PORTB4
CS2
CS2
CS2
PORTB2
CS1
CS1
CS1
PORTB1
CS0
CS0
CS0
AVEC
MODCK
PORTB0
MODCK
PORTB0
NOTE: MODCK has no function after reset.
FIRQ = 1
PPARB = 1
IRQ7
IRQ6
IRQ5
IRQ3
IRQ4
IRQ2
IRQ1
AVEC
MODCK
4-16
MC68340 USER’S MANUAL
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