Datasheet

MC68HC711D3 Data Sheet, Rev. 2.1
Freescale Semiconductor 61
Chapter 5
Input/Output (I/O) Ports
5.1 Introduction
The MC68HC711D3 has four 8-bit input/output (I/O) ports; A, B, C, and D. In the 40-pin version, port A
bits 4 and 6 are not bonded. Port functions are controlled by the particular mode of operation selected, as
shown in Table 1-1. Port Signal Functions.
In the single-chip and bootstrap modes, all the ports are configured as parallel input/output (I/O) data
ports. In expanded multiplexed and test modes, ports B, C, and lines D6 (AS) and D7 (R/W
) are
configured as a memory expansion bus, with:
• Port B as the high-order address bus
• Port C as the multiplexed address and data bus
• AS as the demultiplexing signal
•R/W
as data bus direction control
The remaining ports are unaffected by mode changes.
• Ports A and D can be used as general-purpose I/O ports, though each has an alternate function.
• Port A bits handle the timer functions.
• Port D handles serial peripheral interface (SPI) and serial communications interface (SCI)
functions in addition to its bus direction control functions.
5.2 Port A
Port A shares functions with the timer system and has:
• Three input only pins
• Three output only pins
• Two bidirectional I/O pins
Pins PA6 and PA4 are not bonded in the 40-pin dual in-line package (DIP), and their OC output functions
are unavailable, but their software interrupts are available.
Address: $0000
Bit 7654321Bit 0
Read:
PA7 PA6
(1)
PA5 PA4
(1)
PA3 PA2 PA1 PA0
Write:
Reset: Hi-Z 0 0 0 Hi-Z Hi-Z Hi-Z Hi-Z
Alt. Func.:
And/Or:
PAI
OC1
OC2
OC1
OC3
OC1
OC4
OC1
IC4/OC5
OC1
IC1
—
IC2
—
IC3
—
1. This pin is not bonded in the 40-pin version.
Figure 5-1. Port A Data Register (PORTA)