Rev. 1.00

13

November 22, 2011

HT16C21

Segment Driver Outputs

The LCD drive section includes 20 segment outputs SEG0 ~ SEG19 or 16 segment outputs SEG4 ~ SEG19 which

should be connected directly to the LCD panel. The segment output signals are generated in accordance with the

multiplexed column signals and with the data resident in the display latch. The unused segment outputs should be

left open-circuit when less than 20 or 16 segment outputs are required.

Column Driver Outputs

The LCD drive section includes 4 column outputs COM0~COM3 or 8 column outputs COM0~COM7 which

should be connected directly to the LCD panel. The column output signals are generated in accordance with

the selected LCD drive mode. The unused column outputs should be left open-circuit if less than 4 or 8 column

outputs are required.

Address Pointer

The addressing mechanism for the display RAM is implemented using the address pointer. This allows the loading

of an individual display data byte, or a series of display data bytes, into any location of the display RAM. The

sequence commences with the initialization of the address pointer by the Address pointer command.

Blinker Function

The device contains versatile blinking capabilities. The whole display can be blinked at frequencies selected by

the Blink command. The blinking frequency is a subdivided ratio of the system frequency. The ratio between

the system oscillator and blinking frequencies depends on the blinking mode in which the device is operating, as

shown in the following table:

Blinking Mode

Operating Mode Ratio

Blinking Frequency (Hz)

0

0

Blink off

1

2

2

1

3

0.5

Frame Frequency

The HT16C21 device provides two frame frequencies selected with Mode set command known as 80Hz and

160Hz respectively.