GENERAL DESCRIPTIONThe TM8957 is an embedded high-performance 4-bit microcontroller with LCD
driver on a chip. 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 etc. on a
signal chip.
FEATURES1. Low power dissipation.
1.5V/3V operating voltage range.
2. Powerful instruction set.
Binary addition, subtraction, BCD adjustment. BCD can be performed
directly in addition/ subtraction operations.
4 bits x 4 bits Multiplier
Single-bit manipulation (set, reset, decision for branch).
Various conditional branches.
16 initial working registers and manipulators. (can be extended to all RAM
with Page Mode)
Look-up Table.
LCD driver data transfer.
3. ROM Capacity. 24K x 16 bits.
Instruction ROM Max. Capacity 24K x 16 bits.
Table ROM Max. Capacity 32K / 16K x 8 / 16 bits.
4. RAM Capacity. 6K / 3K / 1.5K x 4 / 8 / 16 bits.
LCD Max. Capacity 256 / 128 / 64 x 4 / 8 / 16 bits.
STACK Max. Capacity 16 x 16 bits.
HL/ZR store Max. Capacity 16 / 16 x 16 bits.
5. With direct/index addressing mode in data RAM access.
6. LCD driver output.
16common outputs and 64 segment outputs.
1/4 ~ 1/16 Duty can be selected by mask option.
1/3 ~ 1/5 Bias can be selected by mask option.
Single instruction to turn off all segments.
COM5 ~ 16 can be defined as CMOS or P_open drain type output port by
mask option.
External regulator mode for VL1/2 by mask option.
7. Input/output ports.
Port IOA 4 pins (with internal pull-low, input signal chattering prevention
circuitry), and can be defined as CX and RFC0 ~ 2 by mask option.
Port IOB 4 pins (with internal pull-low), and can be defined as ELC, ELP,
BZB, BZ by mask option.
Port IOC 4 pins (with internal pull-low, low-level-hold, input signal
chattering prevention circuitry).
Port IOD 4 pins (with internal pull-low, input signal chattering prevention
circuitry), and can be defined as SEG61~64 by mask option.
Port IOE 4 pins (with internal pull-low), and can be defined as RFC3 ~ 5
and CX2 by mask option.
8. Interrupt function.
External factors 5 (INT pin, Port IOA, IOC, IOD & KI input).
Internal factors 5 (Pre-Divider, Timer1, Timer2, Timer3 & RFC).
9. Built-in EL-light driver.
ELC, ELP. Can be defined as IOB1 and IOB2 by mask option.
10. Built-in Alarm, clock or single tone melody generator.
BZB, BZ. Can be defined as IOB3 and IOB4 by mask option.
11. Built-in resistance to frequency converter.
CX, RFC0 ~ 5 CX2,. Can be defined as IOA1 ~ 4 and IOE1 ~ 4 by mask
option.
12. Built-in key matrix scanning function.
KO1 ~ KO16 (Shared with SEG1 ~ 16)
KI1 ~ KI4 (Can be defined as IOB1 ~ 4 by mask option)
13. Three 6-bit programmable timer with programmable clock source.
Read the content at any time
Merge 2 or 3 timers into one 12-bit or 18-bit timer.
Used as a counter for RFC
14. Watchdog timer.
15. Built-in voltage charge halver & 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.
APPLICATIONTimer / Calendar / Calculator / Thermometer