HT16514 datasheet(25/39 Pages) HOLTEK

25 / 39 page

Character Generator RAM (CGRAM)

The CGRAM stores the pixel information (1=pixel on, 0=pixel off) for the eight user-define 5

´8 characters. Valid

CGRAM addresses are 00H to 3FH. CGRAM not used to defined characters can be used as general purpose RAM.

Character codes 00H~07H (or 08H~0FH) are assigned to the user-defined characters (see section 5.0 character font

tables). The table below shows the relationship between the character codes, CGRAM addresses, and CGRAM data

for each user-defined character.

Relationship between CGRAM address and character code (DDRAM) and 5

´7 (with cursor) dot character patterns

(CGRAM)

Note:

²X² means don¢t care

Character code bits 0~2 correspond to CGRAM address bits 3~5 (3 bits: 8 types)

CGRAM address bits 0~2 designate character pattern line position. The 8th line is the cursor position and its

display is formed by a logical OR with the cursor. Maintain the 8th line data, corresponding to the cursor display

position at 0 as the cursor display. If the 8th line data is 1, 1 bit will light up the 8th line regardless of the cursor

presence.

Character pattern row position corresponds to CGRAM data bits 0~4 (bit 4 being at the left).

CGRAM character patterns are selected when character code bits 4~7 are all 0. However, since character

code bit 3 has no effect, the N display example above can be selected by either character code 00H or 08H.

1 for CGRAM data corresponds to display selection and 0 to no selection.

Timing Generation Circuit

Timing generation circuit generates timing signals for the operation of internal circuit such as DDRAM, CGRAM and

CGROM. The RAM reads the timing for display and the internal operation timing by MPU access are generated sepa-

rately to avoid interfering with each other. Therefore, when writing data to DDRAM, for example, there will be no unde-

sirable interference, such as flickering, in areas other than the display area.

HT16514

Rev. 1.00

October 4, 2006

D 7 D 6 D 5 D 4 D 3 D 2 D 1 D 0

H i g h O r d e r B i t

L o w O r d e r B i t

A 5 A 4 A 3

H i g h O r d e r B i t

A 2 A 1 A 0

L o w O r d e r B i t

D 7 D 6 D 5 D 4 D 3 D 2 D 1 D 0

H i g h O r d e r B i t

L o w O r d e r B i t

C u r s o r P o s i t i o n

C h a r a c t e r

P a t t e r n ( 1 )

C h a r a c t e r

P a t t e r n ( 2 )

C h a r a c t e r

P a t t e r n ( 8 )

C h a r a c t e r C o d e ( R A M D a t a )

C G R A M A d d r e s s

C G R A M D a t a

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