Application of OLED display based on single chip microcomputer

1 Introduction

Organic Light Emitting Display (OLED) is a new type of light-emitting and display device. OLED is essentially a thin-film device, and its light-emitting layer is an organic material layer. When current passes through, these organic materials will emit light. Compared with traditional liquid crystal displays (LCDs), in addition to not requiring a backlight source, OLED displays can achieve a thickness of less than 1mm, which makes it possible to realize soft display. In addition, the viewing angle is larger, the brightness is higher, and the colors are richer. OLED can be widely used in handheld devices, communication terminals, instrumentation and other fields.

2 Module Structure

The following uses Visionox VGG12864E-S001 module as an example to introduce the module structure of OLED.

2.1 Module Block Diagram

The OLED display screen of the VGG12864E-S001 module has a structure of 128 columns and 64 rows. It uses two column driver controllers, each with 64 outputs, to drive columns 1-64 and 65-128 respectively; it uses a row driver with 64 row outputs. Figure 1 is a block diagram of the module logic circuit and interface circuit.

2.2 Pin Description

Table 1 is the pin function description of VGG12864E-S001.

Table 1 VGG12864E-S001 pin function table

3 Application Examples

In practical applications, there are two ways to connect the VGG12864E-S001 module to the microprocessor, one is direct access and the other is indirect access. The following takes the direct access method as an example to introduce the connection circuit with 8031.

3.1 Design of driving power conversion circuit

In most embedded systems, only a single +5V power supply is provided externally, so a driving power conversion circuit must be provided for the OLED. LTC3459 is a boost chip launched by Linear Technology. Its input voltage is +1.5V to +5.5V, and its output voltage is +2.5V to +10V. Its maximum quiescent current is 20mA, and when the converter is in shutdown mode, its remaining operating current is less than 1mA. Figure 2 shows its typical circuit, with an output voltage of +10V, which meets the driving voltage input requirements of the VGG12864E-S001 module of +9V to +11V.

3.2 Interface Circuit

The direct access mode is to directly hang the module interface on the computer bus as a memory or I/O device, and the computer operates the module in the same way as accessing a memory or I/O device. Figure 3 is a practical circuit diagram of the direct access mode interface.

3.3 Application Program Example

This program displays the characters "Tel:62780866"

ORG 0000H
AJMP MAIN
COM EQU 20H ; instruction register
DAT EQU 21H ; data register
PAGE EQU 31H ; page address register D2, D1, D0
; the following read and write address allocation is omitted
MAIN: MOV SP, #60H
ACALL INT
ACALL CLEAR
MOV PAGE, #85H
MOV COLUMN, #30H ; the starting column is the 48th column
MOV CODE, #00H ; T
ACALL CWPR
MOV PAGE, #85H
MOV COLUMN, #01H ; e
MOV CODE, #45H
ACALL CWPR
MOV PAGE, #85H
MOV COLUMN, #02H
MOV CODE, #4CH ; l
ACALL CWPR
MOV PAGE, #85H
MOV COLUMN, #03H
MOV CODE, #1AH ; :
ACALL CWPR
MOV R7,#00H
MOV R6,#60H
LOOP: MOV A,R7
MOV DPTR,#TAB
MOVC A,@A+DPTR
MOV CODE,A
MOV PAGE,#05H
MOV COLUMN,R6
ACALL CWPR
INC R7
MOV A,#06H
ADD A,R6
MOV R6,A
CJNE R7,#08,LOOP
SJMP $
TAB: DB 04H,0 5H,06H,07H,08H,07H,09H,09H
; Subroutine