Datasheet

Liquid Crystal Display Driver (LCD)
Technical Data MC68HC908LJ12 — Rev. 2.1
318 Liquid Crystal Display Driver (LCD) Freescale Semiconductor
16.2 Introduction
This section describes the liquid crystal display (LCD) driver module.
The LCD driver module can drive a maximum of 27 frontplanes and 4
backplanes, depending on the LCD duty selected.
16.3 Features
Features of the LCD driver module include the following:
• Software programmable driver segment configurations:
– 26 frontplanes × 4 backplanes (104 segments)
– 27 frontplanes × 3 backplanes (81 segments)
– 27 frontplanes × 1 backplane (27 segments)
• LCD bias voltages generated by internal resistor ladder
• Software programmable contrast control
16.4 Pin Name Conventions and I/O Register Addresses
Three dedicated I/O pins are for the backplanes, BP0–BP2, eighteen
dedicated I/O pins are for the frontplanes, FP1–FP18, and the eight
frontplanes, FP19–FP26, are shared with port C pins. FP0 and BP3
shares the same pin and configured by the DUTY[1:0] bits in the LCD
clock register.
The full names of the LCD output pins are shown in Table 16-1. The
generic pin names appear in the text that follows.
Table 16-1. Pin Name Conventions
LCD Generic Pin Name Full MCU Pin Name Pin Selected for LCD Function by:
FP0/BP3 FP0/BP3 —
BP0–BP2 BP0–BP2 —
FP1–FP18 FP1–FP18 —
FP19–FP22 PTC0/FP19–PTC3/FP22 PCEL in CONFIG2
FP23–FP26 PTC4/FP23–PTC7/FP26 PCEH in CONFIG2