MC68HC711D3_05 Datasheet, PDF (61/138 Pages) Freescale Semiconductor, Inc – Microcontrollers

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 7
6
5
4
3
2
1
Bit 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.: PAI
OC2
OC3
OC4 IC4/OC5 IC1
IC2
IC3
And/Or: OC1
OC1
OC1
OC1
OC1
—
—
—
1. This pin is not bonded in the 40-pin version.
Figure 5-1. Port A Data Register (PORTA)
MC68HC711D3 Data Sheet, Rev. 2.1
Freescale Semiconductor
61