68HC705BD7 datasheet(45/85 Pages) FREESCALE

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SECTION 7: INPUT/OUTPUT PORTS

Page 35

MC68HC05BD7 Rev. 2.0

GENERAL RELEASE SPECIFICATION

Table 7-1: I/O Pin Functions

NOTE:

A “glitch” can be generated on an I/O pin when changing it from an input

to an output unless the data register is first pre-conditioned to the desired

state before changing the corresponding DDR bit from a zero to a one.

7.6

Port C and D Configuration Register

Port C and Port D are shared with PWM, ADC, DDC12AB, and SYNC Processor. The

configuration registers at $0A and $0B are used to configure those I/O pins. They are

default to zero after poWer-on reset. Setting these bits will set the corresponding pins to

the corresponding functions. For example, setting SCL and SDA bits of register $0B will

configure Port D pins 1 and 0 as DDC12AB pins, regardless of DDR1 and DDR0 settings.

When any PWM8-PWM15 bits of CR1 register are set, the corresponding pins of port C

become the PWM output if the corresponding bits in CR2 register are clear. When the pin

is defined as PWM channel, it become an output only pin. When any ADC3-ADC0 bits of

the CR2 register are set, the corresponding pins of port C become the ADC input channels.

When HSYNO or VSYNO is set, the PC2 or PC3 becomes the output of HSYNC or VSYNC

accordingly, see SECTION 10 for the detail description of HSYNO and VSYNO outputs.

When SCL and SDA bits of the CR2 register are set, the DDC12AB use these two pins as

clock and data pins. In summary, the configuration in the CR2 register has higher priority

than in the CR1 register.

R/W

DDR

I/O Pin Functions

The I/O pin is in input mode. Data is written into the output data latch.

Data is written into the output data latch and output to the I/O pin.

The state of the I/O pin is read.

The I/O pin is in output mode. The output data latch is read.

CR1

$000A

reset

⇒

PWM15

0000

3210

PWM14

PWM11

PWM10

PWM9

PWM8

PWM13

PWM12

CR2

$000B

reset

⇒

0000

3210

ADC2

SCL

SDA

ADC1

ADC0

HSYNO

VSYNO

ADC3

Freescale Semiconductor, Inc.

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