MC68HC908MR8 Datasheet, PDF (279/372 Pages) Motorola, Inc – Microcontrollers

Technical Data — MC68HC908MR8
Section 14. Input/Output (I/O) Ports
14.1 Contents
14.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .279
14.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281
14.3.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .281
14.3.2 Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . .282
14.4 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .284
14.4.1 Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .284
14.4.2 Data Direction Register B . . . . . . . . . . . . . . . . . . . . . . . .285
14.5 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .286
14.5.1 Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .287
14.5.2 Data Direction Register C . . . . . . . . . . . . . . . . . . . . . . . .288
14.2 Introduction
Fourteen bidirectional input-output (I/O) pins, two input pins, and six
output pins form three parallel ports.
When using the 28-pin package versions of the MC68HC908MR8, set
the data direction register bits in DDRA such that bits 6, 5, and 4 are
written to a logic 1 (along with any other output bits on PORTA). Setting
PORTA’s data direction register bits 6, 5, and 4 will terminate the input
buffers on that port.
NOTE:
Connect any unused I/O pins to an appropriate logic level, either V_DD or
V_SS. (PWM6–PWM1 pins require no termination). Although the I/O ports
do not require termination for proper operation, termination reduces
excess current consumption and the possibility of electrostatic damage.
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Input/Output (I/O) Ports
Technical Data
279