XC68HC705JB3 Motorola, XC68HC705JB3 Datasheet - Page 101

• Manufacturer Part Number: XC68HC705JB3
• Description: MICROCONTROLLER
• Manufacturer: Motorola

11.1
MC68HC05JB3
REV 1
The MC68HC05JB3 MCU has four pairs of Optical Interfaces, configured through
Port-A. This port has built-in optical coupler interface devices, which can be
directly connected to IR displacement encoders, such as in optical mouse and
optical joystick applications.
OVERVIEW
In practical designs, each axis requires two optical couplers to detect the displace-
ment. Hence, the eight optical interfaces on port-A are enabled in pairs, with each
pair enabled by a bit in the Optical Interface Enable Register ($0E). Figure 11-1
shows a one pair of the optical interface. Table 11-1 shows the port-A configura-
tion for the four pairs.
For optimal performance, the reference voltage used in the optical interface
module is selectable from eight predefined values, as shown in Figure 11-2. and
Table 11-2. This allows the optical interface to be easily configured by software to
match the IR displacement encoders. The reference voltage is selected using the
bits VREF0-VREF2 in the OIER.
Optical Coupler
Pair 1
Pair 2
Pair 3
Pair 4
Table 11-1. Port-A Optical Interface Pairs
OPTICAL INTERFACE
OPTICAL INTERFACE
November 5, 1998
SECTION 11
Port pin used
PA0 and PA1
PA2 and PA3
PA4 and PA5
PA6 and PA7
GENERAL RELEASE SPECIFICATION
Enable bit in OIER
OIE0
OIE1
OIE2
OIE3
MOTOROLA
11-1