GENERAL DESCRIPTION

The TM8725 is an embedded high-performance 4-bit microcomputer with LCD driver. It contains all the necessary functions, such as 4-bit parallel processing ALU, ROM, RAM, I/O ports, timer, clock generator, dual clock operation, Resistance to Frequency Converter(RFC), EL panel driver, LCD driver, look-up table, watchdog timer and key matrix scanning circuitry in a single chip.

BLOCK DIAGRAM

FEATURE

1.Low power dissipation

2.Powerful instruction set (178 instructions).

• Binary addition, subtraction, BCD adjust, logical operation in direct and index addressing mode.

• Single-bit manipulation (set, reset, decision for branch).

• Various conditional branch.

• 16 working registers and manipulation.

• Table look-up.

• LCD driver data transfer.

3.Memory capacity

• ROM capacity3072x 16 bits.

• RAM capacity384x 4 bits.

4.LCD driver output

• 6 common outputs and 40 segment outputs (up to drive 240 LCD segments).

• 1/2 Duty, 1/3 Duty, 1/4 Duty, 1/5 Duty or 1/6Duty is selected by MASK option.

• 1/2 Bias or 1/3 Bias is selected by MASK option.

• Single instruction to turn off all segments.

• COM5~6, SEG1~40 could be defined as CMOS or P_open drain type output by mask option.

5.Input/output ports

• Port IOA4 pins (with internal pull-low), muxed with SEG24~SEG27.

• Port IOB4 pins (with internal pull-low). muxed with SEG28~SEG31

• Port IOC4 pins (with internal pull-low, low-level-hold), muxed with SEG32~SEG35. IOC port had built in the input signal chattering prevention circuitry.

• Port IOD4 pins (with internal pull-low), muxed with SEG36~SEG39. IOD port had built in the input signal chattering prevention circuitry.

6.8 level subroutine nesting.

7.Interrupt function.

• External factors4(INT pin, Port IOC, IOD & KI input).

• Internal factors4(Pre-Divider, Timer1, Timer2 & RFC).

8.Built-in EL-light driver

• ELC, ELP (Muxed with SEG28, SEG29).

9.Built in Alarm, clock or single tone melody generator

• BZB, BZ (Muxed with SEG30, SEG31).

10.Built-in resistance to frequency converter

• CX, RR, RT, RH (Muxed with SEG24 ~ SEG27)

11.Built in key matrix scanning function

• K1~K16 (Shared with SEG1~SEG16).

12.KI1~KI4 (Muxed with SEG32 ~ SEG35)

13.Two 6-bit programmable timer with programmable clock source.

14.Watch dog timer.

15.Built-in Voltage doubler, halver, tripler charge pump circuit.

16.Dual clock operation

• slow clock oscillation can be defined as X’tal or external RC type oscillator by mask option.

• fast clock oscillation can be defined as 3.58MHz ceramic resonator, internal R or external R type oscillator by mask option.

17.HALT function.

18.STOP function.