EM78P813

8-bit OTP Micro-controller

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* This specification is subject to change without notice.

37

2004/8/19

(V1.6)

Bias

VC1

VC2

VC3

VC4

VC5

1/5

V1

4/5*V1

3/5*V1

2/5*V1

1/5*V1

1/6

V1

5/6*V1

4/6*V1

2/6*V1

1/6*V1

1/7

V1

6/7*V1

5/7*V1

2/7*V1

1/7*V1

Bit 2~Bit 3(LCD0~LCD1) : LCD operation function definition.

LCD1

LCD0

LCD operation

0

0

Disable

0

1

Blanking

1

0

Reserved

1

1

LCD enable

<Note 1> Key strobe and Key check functions should be normal operating whenever LCD is

enabled or disabled.

<Note 2> When LCD operation disable:

(1) Internal Voltage regulator will disable and VREF pin is into high impedance.

(2) Charge pump circuit disable.

(3) Internal non-Inverter OP Amp power off.

The controller can drive LCD directly. LCD block is made up of LCD driver, display RAM, segment output pins,

common output pins and LCD operating bias pins.

Duty is determined by

determined by LCD mode register RE PAGE2 Bit 0~ Bit 1.

When 16 LCD commons and 1/4 duty are used, LCD operating bias pins VC1, VC2, VC4 and VC5 need to be

connected 0.1uF capacitors to the ground (VC3 is not necessary). When 24 and 32 LCD common is used, all LCD

operating bias pins VC1 ~ VC5 need to be connected 0.1uF capacitors to the ground.

LCD driver can be controlled as different driving ability (refer to RD PAGE2 register).

The basic structure contains a timing control which uses the basic frequency 32.768kHz to generate the proper timing

for different duty and display access. RE PAGE2 register is a command register for LCD driver and display. The LCD

display (disable, enable, blanking) is controlled by RE PAGE0 Bit 2 ~ Bit 3 and the driving duty is decided by RE

PAGE2 Bit 0 ~ Bit 1. LCD display data is stored in data RAM which address and data access controlled by registers

R9, RA PAGE1 and RB PAGE1.

User can regulate the contrast of LCD display by RD PAGE2 (BIAS4..BIAS0). Up to 32 levels contrast is convenient

for better display. And the internal voltage follower can afford large driving source.

Bit 4 (KEYSCAN) : Key scan function enable control bit

0/1

disable/enable

If you enable key scan function LCD waveform will has a small pulse within a period like fig.23