RAiO
RA8835
Dot Matrix
LCD Controller
Q&A
Preliminary Version 1.2
July 13, 2009
RAiO Technology Inc.
©Copyright RAiO Technology Inc. 2009
RAiO TECHNOLOGY INC.
www.raio.com.tw
RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
Update History
Version
1.0
Date
July 13, 2009
RAiO TECHNOLOGY INC.
Description
Preliminary Version
www.raio.com.tw
RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
問題一：如何避免 RA8835 寫入或讀出資料問題？例如 RA8835 無法正確顯示，或者是 MCU 無法從 display
memory 讀回一個正確的資料？
Q1: How to avoid the writing or the reading problem of RA8835, e.g. RA8835 can not correctly display on LCM or
MCU can not read from display memory an un-correct data.
回覆一：LCM 的顯示系統上，通常在 PCB 上會有一個連接 MCU 以及 RA8835 的 bus line 架構，為了避免錯誤
顯示或錯誤讀寫，我們會建議在 bus line 上加一 1K~3.3KΩ的 pull-up resister 來穩定 bus 信號。或者，MCU interface
的 cable 儘量勿長於 30 公分。
Ans. 1: LCM display system ordinary have a bus line configuration on printed circuit boards for data communication
between MCU and RA8835. To avoid the display/ the access error, we suggest that bus signals might be better
stabilized by pulling up to VCC using the resistors around 1k-3.3 k
or keeping the length of MCU interface less then
30CM.
請參考下列相關圖示說明：
Please refer to the following picture.
VDD
1K~3.3KΩ
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
RA8835
MCU
/CS
A0
/RD
/WR
/CS
A0
/RD
/WR
1K~3.3KΩ
VDD
Figure 1 Pull-up resister
MCU
≦30CM is
recommendedd
RA8835
Figure 2 MCU interface wire length
RAiO TECHNOLOGY INC.
www.raio.com.tw
RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
問題二. RA8835/RA8835A 暫存器的初值為何?
Q2: What are the register default values of the RA8835/RA8835A?
回覆二：請參考下列圖表說明：
Ans2: Please refer to the following table.
Class
System control
Display control
Command
System Set
Display
Hex
40
58/59
ON/OFF
SCROLL
CSRFORM
CGRAM ADR
Drawing
44
5D
5C
Default value
RA8835
RA8835A
P1
00H
00H
P2
00H
00H
P3
00H
00H
P4
00H
00H
P5
40H
40H
P6
F0H
F0H
P7
00H
00H
P8
00H
00H
P1
OFF(0)
ON(1)
P1
00H
00H
P2
00H
00H
P3
00H
00H
P4
00H
00H
P5
00H
00H
P6
00H
00H
P7
00H
00H
P8
00H
00H
P9
00H
00H
P10
00H
00H
P1
00H
00H
P2
00H
00H
P1
00H
00H
P2
00H
00H
NONE
4CH
4CH
CSRDIR
4C to 4F
HDOT SCR
5A
P1
00H
00H
OVLAY
5B
P1
00H
1CH
CSRW
46
P1
00H
00H
P2
00H
00H
NONE
00H
00H
control
CSRR
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Parameter
47
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
問題三. RA8835/RA8835A 的 ESD/Latch up 特性為何?
Q3: What are the ESD and Latch up features of the RA8835/RA8835A?
回覆三：請參考下列圖表說明：
Ans3: Please refer to the following table.
RA8835
ESD Sensitivity
RA8835A
+4KV/-5KV,
+/-6.5KV,
Pass(HBM)
V Class-3
V Class-3
Latch-up
+/-200mA,
+/-600mA,
IT Class-3
IT Class-3
問題四.在 RA8835 Data sheet 版本 2.0 的 82 和 83 頁，這裡有兩個不同的 8080 時序圖，何時為其各別的使用時
機。
Q4: There are two different 8080 timing diagrams in the page 82 and 83 of the Datasheet Rev. 2.0. of RA8835. When
does each one apply?
回覆四：就 8080 系列的介面而言，在 datasheet 2.0 的 timing-1 以及 timing-2 是有些許的不同。以 timing-2 來說，
資料存取的週期必須要大於 write pulse(/WR 保持在低準位的期間)。在 timing-1 則不需要如同 timing-2 的動作，
但是在存取 RA8835 之前，data bus 必須要先預設為 00H 或者是 FFH。相關的圖示說明，請參照下方的時序圖。
Ans4: In 8080 family interface, there is a little bit difference between timing-1 and timing-2 of the Datasheet Rev. 2.0.
In the case of timing-2, the data access period has to be longer than the write pulse (/WR keeps in logic low). The
timing-1 need not to be like that, but the data bus should be set to 00H/FFH before accessing RA8835. The related
timing charts are shown below, please have a look.
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
問題五.使用 RA8835 如何減少顯示畫面上的雪花現象？
Q5: How to reduce the flicker/snow effect with RA8835?
回覆五：當 RA8835 內部的掃瞄線路在處理掃瞄任務時，若同時經由 MPU 來做存取 DDRAM 的動作，那麼掃
瞄資料將被強迫的到一個錯誤的值而造成閃爍或雪花現象。當閃爍或雪花現象太嚴重時，其將使影響整體的顯
示畫面。我們會建議使用使用者在寫入資料到 DDRAM 之前，做一個 check busy 的動作來減少閃爍或雪花的現
象。相關的程式說明如下：
Ans5: When the scan logic of RA8835 is processing scan task at the same time the DDRAM is accessed by the MPU,
the scan data will be forced to get a wrong one and it might cause the flicker or the snow effect. When the flicker or
snow is too much, it will infect the display appearance. To reduce the flick/snow effect, it is suggested that user can use
a check busy subroutine before writing data into DDRAM. The related demo program is described as below.
void lcd_datawrite(unsigned char datax)
{
lcd_chkbusy();
//It is recommended that execute check busy subroutine before accessing display
memory
lcd_SEL1 = 0;
lcd_A0 = 0;
lcd_DATA = datax;
lcd_CS = 0;
lcd_WR = 0;
lcd_WR = 1;
lcd_CS = 1;
lcd_A0 = 1;
}
unsigned char lcd_cmdread(void)
{
unsigned char address_cmd;
lcd_DATA=0xff;
lcd_SEL1 = 0;
lcd_A0 = 0;
lcd_CS = 0;
lcd_RD = 0;
address_cmd = lcd_DATA;
lcd_RD = 1;
lcd_CS = 1;
lcd_A0 = 0;
return(address_cmd);
}
void lcd_chkbusy(void)
{
unsigned char busy;
do {
busy =(lcd_cmdread() & 0x40);
}while(busy);
}
問題六.如何在 RA8835 外部的 CG-ROM 上自建一個新的字型？
Q6: How to create a new character (symbol/pattern) on the CG-ROM of RA8835?
回覆六：請參考下列範例程式。
Ans6: Please refer to the following sample program.
RAiO TECHNOLOGY INC.
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
void main(void)
{
lcd_reset();
lcd_initial();
lcd_clear();
// initial setting
// Clear memory
//===============================================================
// Display a 8x8 / 8x16 char (External CG-ROM)
//--------------------------------------------------------------// M0 = 1 for External CG-ROM
// M1 = 1 for D6 correction, 0 for N0 D6 correction
// M2 = 1 for 8x16, 0 for 8x8
//===============================================================
lcd_cmdwrite(0x40);
//SYSTEM SET
lcd_datawrite(0x35);
//p1 ==> 8x16 , No D6 Correction, External CG-ROM
lcd_cmdwrite(0x59);
//DISP ON, NOTE ===> this command is always following
//SYSTEM SET CMD
char_generate_EX_CGROM(0xF050, Ext_char1);
char_generate_EX_CGROM(0xF060, Ext_char2);
lcd_cursorxy(0x00,0x00);
lcd_cmdwrite(0x42);
lcd_datawrite(0x05);
lcd_datawrite(0x06);
}
void lcd_reset(void)
{
lcd_RES = 1;
delay1ms(2);
lcd_SEL1 = 0;
lcd_A0 = 0;
lcd_WR = 1;
lcd_RD = 1;
lcd_CS = 1;
lcd_RES = 0;
delay1ms(100);
lcd_RES = 1;
delay1ms(500);
}
void lcd_initial(void)
{
lcd_cmdwrite(0x40);
lcd_datawrite(0x30);
lcd_datawrite(0x87);
lcd_datawrite(0x0F);
lcd_datawrite(0x27);
lcd_datawrite(0x30);
lcd_datawrite(0xef);
lcd_datawrite(0x28);
lcd_datawrite(0x00);
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//SYSTEM SET
//p1 ==> single panel, no screen top-line
//p2 ==> Font Width = 8
//p3 ==> Font Height = 15
//p4 ==> Set the address range covered by one display line.
//p5 ==> line length = 48 bytes = TC/R = 48 = 30h
//p6 ==> L/F
//p7 ==> Horizontal address range = 28h = 40
//p8
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
lcd_cmdwrite(0x44);
lcd_datawrite(0x00);
lcd_datawrite(0x00);
lcd_datawrite(0xf0);
//SCROLL
//sa1-L
//sa1-H
//sL1
0xf0
lcd_datawrite(0x80);
lcd_datawrite(0x25);
lcd_datawrite(0xf0);
//sa2-L
//sa2-H
//sL2
lcd_datawrite(0x00);
lcd_datawrite(0x70);
//sa3-L
//sa3-H
lcd_datawrite(0x00);
lcd_datawrite(0x80);
//sa4-L
//sa4-H
lcd_cmdwrite(0x5a);
lcd_datawrite(0x00);
//HDOT SCR
// 0x00
lcd_cmdwrite(0x58);
lcd_datawrite(0x54);
//DISP OFF
lcd_cmdwrite(0x5d);
lcd_datawrite(0x07);
lcd_datawrite(0x07);
//CSR FORM
//CRX
//CRY
lcd_cmdwrite(0x59);
lcd_datawrite(0x54);
//DISP ON
lcd_cmdwrite(0x5b);
lcd_datawrite(0x01);
lcd_cmdwrite(0x4c);
// Cursor direction ==> Right
}
void lcd_clear(void)
{
unsigned int i;
lcd_cmdwrite(0x4c);
// Direction ==> Right
lcd_cursorxy(0x00,0x00);
lcd_cmdwrite(0x42);
for(i=0;i<0xffff;i++)
{
lcd_datawrite(0x00);
}
}
//==========================================================
//This subroutine is for creating a new character on external CG-ROM
//Note：The address of CGRAM_SA must be set at F000H to FFFFH）
//==========================================================
void char_generate_EX_CGROM(unsigned int CGRAM_SA, char code *char_data)
{
int a, pos_H, pos_L;
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
pos_H = CGRAM_SA >> 8;
pos_L = CGRAM_SA & 0x00ff;
lcd_cmdwrite(0x4c);
lcd_cmdwrite(0x46);
lcd_datawrite(pos_L);
lcd_datawrite(pos_H);
lcd_cmdwrite(0x42);
for(a=0;a<16;a++)
{
lcd_datawrite(*char_data);
char_data++;
}
}
char code Ext_char1[]=
{
0x00,0x03,0x3f,0x1d,0x01,0x01,0x01,0x0f,0x07,0x03,0x01,0x01,0x01,0x07,0x7f,0x38,
};
char code Ext_char2[]=
{
0x38,0xfc,0xc0,0x00,0x80,0x80,0x80,0xe0,0xf0,0xe0,0x80,0x80,0x9c,0xfe,0xff,0x00,
};
問題七.如何在 RA8835 內部的 CG-RAM 上自建一個新的字型？
Q7: How to create a new character (symbol/pattern) on the internal CG-RAM of RA8835?
回覆七：請參考下列範例程式。
Ans7: Please refer to the following sample program.
void main(void)
{
lcd_reset();
lcd_initial();
lcd_clear();
// initial setting
// Clear memory
//===============================================================
// Display a 8x8 / 8x16 / 16x16 char (Internal CG-RAM)
//--------------------------------------------------------------// M0 = 0 for Internal CG-RAM,
// M1 = 1 for D6 correction, 0 for N0 D6 correction
// M2 = 1 for 8x16, 0 for 8x8
//===============================================================
lcd_cmdwrite(0x40);
//SYSTEM SET
lcd_datawrite(0x34);
//p1 ==> 8x16 , No D6 Correction, Internal CG-RAM
lcd_cmdwrite(0x59);
//DISP ON, NOTE ===> this command is always following
//SYSTEM SET CMD
char_generate(0x4800, Ext_char1);
char_generate(0x4810, Ext_char2);
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
lcd_cursorxy(0x00,0x00);
lcd_cmdwrite(0x42);
lcd_datawrite(0x80);
lcd_datawrite(0x81);
}
void lcd_reset(void)
{
lcd_RES = 1;
delay1ms(2);
lcd_SEL1 = 0;
lcd_A0 = 0;
lcd_WR = 1;
lcd_RD = 1;
lcd_CS = 1;
lcd_RES = 0;
delay1ms(100);
lcd_RES = 1;
delay1ms(500);
}
void lcd_initial(void)
{
lcd_cmdwrite(0x40);
lcd_datawrite(0x30);
lcd_datawrite(0x87);
lcd_datawrite(0x0F);
lcd_datawrite(0x27);
lcd_datawrite(0x30);
lcd_datawrite(0xef);
lcd_datawrite(0x28);
lcd_datawrite(0x00);
//SYSTEM SET
//p1 ==> single panel, no screen top-line
//p2 ==> Font Width = 8
//p3 ==> Font Height = 15)
//p4 ==> Set the address range covered by one display line.
//p5 ==> line length = 48 bytes = TC/R = 48 = 30h
//p6 ==> L/F
//p7 ==> Horizontal address range = 28h = 40
//p8
lcd_cmdwrite(0x44);
lcd_datawrite(0x00);
lcd_datawrite(0x00);
lcd_datawrite(0xf0);
//SCROLL
//sa1-L
//sa1-H
//sL1
0xf0
lcd_datawrite(0x80);
lcd_datawrite(0x25);
lcd_datawrite(0xf0);
//sa2-L
//sa2-H
//sL2
lcd_datawrite(0x00);
lcd_datawrite(0x70);
//sa3-L
//sa3-H
lcd_datawrite(0x00);
lcd_datawrite(0x80);
//sa4-L
//sa4-H
lcd_cmdwrite(0x5a);
lcd_datawrite(0x00);
//HDOT SCR
// 0x00
lcd_cmdwrite(0x58);
lcd_datawrite(0x54);
//DISP OFF
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
lcd_cmdwrite(0x5d);
lcd_datawrite(0x07);
lcd_datawrite(0x07);
//CSR FORM
//CRX
//CRY
lcd_cmdwrite(0x59);
lcd_datawrite(0x54);
//DISP ON
lcd_cmdwrite(0x5b);
lcd_datawrite(0x01);
lcd_cmdwrite(0x4c);
// Direction ==> Right
void lcd_clear(void)
{
unsigned int i;
lcd_cmdwrite(0x4c);
// Direction ==> Right
}
lcd_cursorxy(0x00,0x00);
lcd_cmdwrite(0x42);
for(i=0;i<0xffff;i++)
{
lcd_datawrite(0x00);
}
}
//==========================================================
// This subroutine is used for creating a new character on the internal CG-RAM
//==========================================================
void char_generate(unsigned int CGRAM_SA, char code *char_data)
{
int a, pos_H, pos_L;
pos_H = CGRAM_SA >> 8;
pos_L = CGRAM_SA & 0x00ff;
lcd_cmdwrite(0x5c);
lcd_datawrite(0x00);
lcd_datawrite(0x40);
// Set the start address at the 4000h
lcd_cmdwrite(0x4c);
lcd_cmdwrite(0x46);
lcd_datawrite(pos_L);
lcd_datawrite(pos_H);
lcd_cmdwrite(0x42);
for(a=0;a<16;a++)
{
lcd_datawrite(*char_data);
char_data++;
}
}
char code Ext_char1[]=
{
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RA8835
Preliminary Version 1.0
Dot Matrix LCD Controller
0x00,0x03,0x3f,0x1d,0x01,0x01,0x01,0x0f,0x07,0x03,0x01,0x01,0x01,0x07,0x7f,0x38,
};
char code Ext_char2[]=
{
0x38,0xfc,0xc0,0x00,0x80,0x80,0x80,0xe0,0xf0,0xe0,0x80,0x80,0x9c,0xfe,0xff,0x00,
};
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