ST7038 datasheet(22/63 Pages) SITRONIX

22 / 63 page

ST7038

Ver 1.3

22/63

2008/05/27

Character Generator RAM (CGRAM)

The Character Generator RAM is reserved for customers to rewrite character patterns by program. Total 8 character patterns

(each one is 5x8-dot) can be stored in CGRAM. Each byte of CGRAM has 5 bits and a character pattern (5x8-bit) uses 8

bytes to store its pattern. Refer to Table 6 for the relationship among DDRAM data, CGRAM addresses and CGRAM data.

Areas that are not used for display can be used as general data RAM (* only 5-bit per byte).

To display the CGRAM Data (customized Character Pattern), write the Character Code (light green part in Table 6) into

DDRAM (be sure the OPR2 & OPR1 settings are correct… refer to Table 7).

Display CGRAM Pattern

Generate CGRAM Pattern

Character Code

(DDRAM Data)

CGRAM Address

(Instruction)

Character Pattern

(CGRAM Data)

Table 6

Relationship among CGRAM Address, Character Code (DDRAM Data) & Character Pattern (CGRAM Data)

Notes:

Character code bits 2 to 0 are identical with CGRAM address bits 5 to 3 (the red block and red arrow).

These 3 bits indicate there are maximum 8 character patterns can be generated by CGRAM.

CGRAM address bits 2 to 0 point to the character pattern line position. The 8th line is the cursor position and its display

is formed by a logical OR with the cursor. Try to keep the 8th line data at 0. Otherwise, those pixels with 1 in the 8th line

will be turned ON no matter the cursor is ON or OFF.

Character pattern row positions correspond to CGRAM data bits 4 to 0 (bit 4 is on the left side).

As shown in Table 6, character patterns in CGRAM are selected when character code bits 7 to 4 are all 0 (assume

OPR2 & OPR1 setting are correct). However, since character code bit 3 is not used, the “R” pattern in Table 6 can be

selected by either character code 01H or 09H.

In CGRAM data, “1” corresponds to display selection, “0” to non-selection while “-” indicates no effect.

Different CGRAM size can be selected by instruction (OPR2 & OPR1). Please refer to Table 7 and instruction

description.

ST7038 Datasheet(PDF) 22 Page - Sitronix Technology Co., Ltd.