78M6612-IMSLASHFSLASHP datasheet(13/46 Pages) MAXIM

13 / 46 page

DS_6612_001

78M6612 Data Sheet

Rev 2

1.5.6 Optical Interface

The device includes an interface to implement an IR/optical port on UART1. The pin TX1 is designed to

directly drive an external LED for transmitting data on an optical link. The pin RX1 is designed to sense

the input from an external photo detector used as the receiver for the optical link. The IR/optical interface

is not supported in all firmware libraries. Contact Maxim support for more information.

1.5.7 Digital I/O

The device includes up to 18 pins (QFN 68 package) or 16 pins (LQFP 64 package) of general purpose

digital I/O. These pins are compatible with 5V inputs (no current-limiting resistors are needed). Some of

them are dedicated DIO (DIO3), some are dual-function that can alternatively be used as LCD drivers

(DIO4-11, 14-17, 19-21) and some share functions with the optical port (DIO1, DIO2). On reset or

power-up, all DIO pins are inputs until they are configured for the desired direction under MPU control.

The pins are configured by the DIO registers and by the five bits of the LCD_NUM register (located in I/O

RAM). Once declared as DIO, each pin can be configured independently as an input or output with the

DIO_DIRn bits. A 3-bit configuration word, DIO_Rx, can be used for certain pins, when configured as

DIO, to individually assign an internal resource such as an interrupt or a timer control. Table 2 lists the

direction registers and configurability associated with each group of DIO pins. Table 3 shows the con-

figuration for a DIO pin through its associated bit in its DIO_DIR register.

Tables showing the relationship between LCD_NUM and the available segment/DIO pins can be found in

Section 3.5 Connecting LCDs and in Section 4.3 I/O Description under LCD_NUM[4:0].

78M6612-IM/F/P Datasheet(PDF) 13 Page - Maxim Integrated Products