GENERAL DESCRIPTIONThe 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.
FEATURES1. 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 capacity 3072 x 16 bits.
RAM capacity 384 x 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 IOA 4 pins (with internal pull-low), muxed with SEG24~SEG27.
Port IOB 4 pins (with internal pull-low). muxed with SEG28~SEG31
Port IOC 4 pins (with internal pull-low, low-level-hold), muxed with SEG32
~ SEG35. IOC port had built in the input signal chattering prevention
circuitry.
Port IOD 4 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 factors 4 (INT pin, Port IOC, IOD & KI input).
Internal factors 4 (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.