RAiO
RA8815 /RA8816
圖形/文字
LCD 驅動控制器
常見使用問題及說明
Version 1.0
July 13, 2009
RAiO Technology Inc.
@Copyright RAiO Technology Inc. 2009
RAiO TECHNOLOGY INC.
www.raio.com.tw
RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
Update History
Version
1.0
Date
July 13, 2009
RAiO TECHNOLOGY INC.
Description
Preliminary Version
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RA8815/RA8816
Preliminary Version 1.0
文字/图形 LCD 驅動控制器
Basic Information
Question 1:
As the Figure 1, why can not press SW0 and SW1 at the same time?
問題 1. 參考圖 1，為何 SW0 和 SW1 無法同時動作？
Question 2:
What is the duration of reset pulse after power-on with RA8816?
問題 2. 在 RA8816 被 Power-on 後，Reset pulse 需要維持多長的時間？
Question 3:
Datasheet doesn't specifies if RST is standard logic input pin or if it has some hysteresis included (e.g.
Schmitt trigger input) to allow to input slow rise and falling edges on RST signal. Can RA8816 be reset by
simple RC circuit?
問題3. 在datasheet中並未規範RST Pin是一邏輯的輸入腳或內含遲滯線路(如Schmitt trigger input)，去允許輸
入正緣或負緣的RST 信號。
Question 4:
Why did we get a failure output when we made an auto-scroll function to the picture which is greater than 48
display lines?
問題 4. 為何在做 auto-scroll function 時，當圖片超過 48 條顯示線時，我們會得到一個錯誤的顯示輸出？
Question 5:
Is there any software command to reset RA8815/RA8816 instead of hardware reset (RST)?
問題 5.
Question 6:
How to choose the resistor value for the internal RC oscillator of RA8815 which be connected between pins
RA and RB of RA8815?
問題 6. 如何選用 RA8815 的內部 RC 振盪器的電阻值，其是被接在 RA8815 的 RA 與 RB 上的？
Question 7:
How to choose the capacitor value for the bias circuit of RA8815/RA8816?
問題 7. 如何選用 RA8815/RA8816 的高壓電路電容值？
Question 8:
For RA8815, between the issues of two different commands or data, is it necessary to add a delay time and
how long is the delay time will be recommended to use?
問題 8. 以 RA8815 為例，在不同需求的兩個 commands 或 data 之間，其是須要加入一個延遲時間的嗎？還
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RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
有多長的 delay time 是被建議採用的？
Question 1: As the Figure 1, why can not press SW0 and SW1 at the same time?
VDD
KIN0
10KΩ
short
KST0
SW0
(Logical “High”)
SW1
(Logical “Low”)
KST1
Figure-1
Answer: Please be noted that using the 2x strobes and 1x input mode, pressed SW 0 and SW 1 at the same
time could lead to a short circuit. Due to the KST0 and KST1 are scan signals and different logical level at the
same time, so could not be pressed the 2 keys together simultaneously. We would like to suggest user to
change the application circuit to 1x strobe and 2x inputs, or refer to the following 2x strobe and 1x input circuit
which is the suggested circuits to avoid the above failure problem.
回覆：請注意，在使用 2x strobes and 1x input mode 時，同時按下 SW0 以及 SW1 可能導致短路的現象發生，
這是由於 KST0 以及 KST1 等掃瞄信號在同一時間內是屬於不同的邏輯準位，因此不可以同步地一起按下兩個
按鍵。我們會建議使用者修改上述的電路為 1x strobe and 2x inputs(Figure-2-3)，或參考下述建議的 2x strobe
and 1x input circuit 去避免前述的錯誤問題。
2X STROBES AND 1X INPUT
SUGGESTED CIRCUIT(1)
2X STROBES AND 1X INPUT
SUGGESTED CIRCUIT(2)
VDD
KIN0
10KΩ
SW0
SW1
VDD
10KΩ
KST0
KIN0
KST0
SW0
KST1
SW1
VDD
SW0
10KΩ
VDD
VDD
10KΩ
SW1
KIN1
74AC125
RAiO TECHNOLOGY INC.
VDD
KIN0
KST1
Figure-2-1
1X STROBE AND 2X INPUTS
CIRCUIT
Figure-2-2
※It is recommended to use this circuit
Figure-2-3
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KST0
RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
Question 2: What is the duration of reset pulse after power-on with RA8816?
Answer: The duration of reset pulse after power-on should be more than 5ms.
回覆：Power-on 後的 Reset pulse 週期必須大於 5ms。
Question 3: Datasheet doesn't specifies if RST is standard logic input pin or if it has some hysteresis included
(Schmitt trigger input) to allow slow rise and falling edges on RST signal. Can RA8816 be reset by simple RC
circuit?
Answer: The /RST pin of RA8815 and RA8816 is a Schmitt trigger reset input and active low, it can be reset
by a simple external RC circuit as the Figure-3.
回覆：RA8815以及RA8816的/RST pin為低準位輸入的Schmitt trigger架構，如下圖三，其可被reset經由一個
簡單的外部RC電路。
VDD
/RST
Figure-3
Question 4: Why did we get a failure output when we made an auto-scroll function to the picture which is
greater than 48 display lines?
Answer: If the register “MWMR” of RA8816［Memory Write Mode Register］ is only set to “normal display
range”, then the auto-scroll function will be worked well. But depend on the design for RA8816, if the “MWMR”
is set to “display range + scroll-buffer” or “scroll-buffer” will cause a wrong display pattern when the scrolling
range is greater than 48 pixels in vertical direction. In this case, please refer to the following program to solve
above application issue.
回覆：如果 RA8816 的暫存器”MWMR”單純被設定為” normal display range”，則自動捲動功能可正常顯示。但
依照 RA8816 的設計，若”MWMR”是被設定為“display range + scroll-buffer”或“scroll-buffer”，當其的捲動範圍
是大於 48 個垂直顯示 pixel，將會造成錯誤的顯示畫面。在此類的情況下，請參考以下的程式來排除上述的應
用問題。
void display_scroll-buffer(void)
{
uchar temp, i, j;
//the following related functions please refer to the demo-code of RA8816 from RAiO’s website
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RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
LCD_Initial();
LCD_Clear();
Delay100ms(1);
LCD_ON();
LCD_CmdWrite(SWSXR, B0000_0000);
LCD_CmdWrite(SWSYR, B0000_0000);
LCD_CmdWrite(SWRXR, 17);
LCD_CmdWrite(SWRYR, 63);
LCD_CmdWrite(ASCR, B0011_0000);
LCD_CmdWrite(SCCR, B0010_1110);
//Set Scroll Range
LCD_CmdWrite(MWMR, B0011_0011);
//set normal display range (menory range of write)
LCD_CmdWrite(SCCR, B0110_1110);
LCD_GotoXY(0, 0);
LCD_PrintStr(sRAiO28, 2);
Delay100ms(10);
//write data to show
LCD_GotoXY(0, 16);
LCD_PrintStr(sRAiO29, 4);
Delay100ms(10);
LCD_GotoXY(0, 32);
LCD_PrintStr(sRAiO30, 6);
Delay100ms(10);
LCD_GotoXY(0, 48);
LCD_PrintStr(sRAiO31, 8);
Delay100ms(10);
LCD_GotoXY(0, 0x40);
//write data in display+buffer memory
LCD_PrintStr(sRAiO32, 10);
Delay100ms(10);
LCD_CmdWrite(MWMR, B0111_0011);
//set display+scroll-buffer (menory range of write)
LCD_CmdWrite(SCCR, B1111_1010);
j = 0;
while(1)
{
LCD_GotoXY(0, 0);
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//(A)write data in buffer memory
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RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
LCD_DataWrite(0xa3);
LCD_DataWrite(0x41 + j);
j++;
//(1)
LCD_CmdWrite(SCCR, B0001_1100);
for(i=0; i<64 ; i++)
//set direction
//(B)scroll 64 lines
{
LCD_CmdWrite(SCOR, i);
Delay100ms(2);
}
//(2)
LCD_CmdWrite(SCCR, B0001_1000);
for(i=16; i>0 ; i--)
//(C)scroll 16 lines
{
LCD_CmdWrite(SCOR, i);
Delay100ms(2);
}
}
Delay100ms(200);
}
Question 5: Is there any software command to reset RA8815/RA8816 instead of hardware reset (RST)?
Answer: Yes, RA8815/RA8816 provides software reset function instead of hardware reset circuit (SRST: bit 7
of PWRR). Set SRST bit to 1, all of the register will be initialed again except the display memory. Once this bit
is set to 1 then RA8815/RA8816 has to take 50us for operation and cannot accept any new command from
MCU. If the SRST bit is cleared to 0, then RA8816 will do its normally display operation.
回覆：是的，RA8815/RA8816提供一軟體重置功能以取代硬體的重置電路 (SRST: bit 7 of PWRR)。將SRST
這個位元設定為1，除了顯示記憶體之外，全部的暫存器將被重新初始化。一旦這個位元被設定為1之後，
RA8815/RA8816必須經過50微秒來完成重置的動作，在這一段其間其不能接受任何來自於MCU的指令。若將
SRST位元清除為0，則RA8816將會進行其一般地顯示工作。
Question 6: How to choose the resistor value for the internal RC oscillator of RA8815 which be connected
between pins RA and RB of RA8815?
Answer: The system clock of RA8815 is generated by the internal oscillation circuitry and it needs an external
resistor which is connected between pin RA and RB. Normally, the resistor value is 270Kohm and generated
frequency is around 45 KHz.
RAiO TECHNOLOGY INC.
www.raio.com.tw
RA8815/RA8816
文字/图形 LCD 驅動控制器
Preliminary Version 1.0
回覆：RA8815 的系統頻率是產生自內部的振盪電路，但其需要一個接在 RA 與 RB pin 之間的外部電阻。一般
來說，在電阻值為 270Kohm 的情況下，其產生的振盪頻率大約是 45KHz。
Question 7: How to choose the capacitor value for the bias circuit of RA8815/RA8816?
Answer: All of the capacitors at the Figure-4 are recommended to use 1uF.
回覆：如圖 4，所有的電容值是建議使用 1uF。
VLCD
C1
C2M
C1
C2P
C1M
C1P
C1
C2
C2
C2
VREF
V0
V1
C2
V2
C2
V3
C2
V4
VSS
Figure-4 (3X Set-up Voltage Circuit)
Question 8: For RA8815, between the issues of two different commands or data, is it necessary to add a delay
time and how long is the delay time will be recommended to use?
Answer:Because of the system clock of RA8815 is generated by the internal circuit and external resister, the
resistor is connected between pin RA and RB. Normally the resistance is recommended to use 270Kohm and
the clock frequency will be around 45 KHz. When the serial interface is using, user has to heed that the data
access speed to RA8815 can not be to fast, that’s because the RA8815 needs a little time to process the
received command or data. To access RA8815, we would like to suggest user to add a delay time between
two sequential commands or data to avoid the wrong access problem. The recommended delay times are
following below.
1. The delay time is recommended more than 2T (2 x (1/system clock)) when writing the sequential
commands or data to RA8815. For example, If system clock = 55 KHz, then the delay time has to be more
than 35us.
2. The delay time is recommended more than 17T (17 x (1/system clock)) when accessing the 8x8/8x16 Half
Size Font from RA8815. For example, If system clock = 55 KHz, then the delay time has to be more than
0.35ms.
3. The delay time is recommended more than 33T (33 x (1/system clock)) when accessing the 16x16 Full Size
Chinese Font from RA8815. For example, If system clock = 55 KHz, then the delay time has to be more than
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RA8815/RA8816
Preliminary Version 1.0
文字/图形 LCD 驅動控制器
0.7ms.
回覆：由於 RA8815 內部 RC 所產生的 system clock，以外部電阻為 270KΩ 而言，system clock 只有 45KHz
左右，若外部的 MCU 給 command/data 間隔太近的話，將可能導致 RA8815 無法確實接收來自 MCU 的指令
或資料。所以我們會建議在相關的條件下，增加一 delay time，以避免 RA8815 出現錯誤存取的問題。
以 System clock=45KHz 為例:
1. 連續兩筆 Command read/write 的 delay time 建議大於 2T(兩倍的 RA8815 system clock cycle), delay time
的建議值為大於 35uS。
2. 連續兩筆讀取 8x8/8x16 Half Size Font 的 delay time 建議大於 17T(17 倍的 RA8815 system clock cycle),
delay time 的建議值為大於 0.35mS
3. 連續兩筆讀取 16x16 Full Size Chinese Font 的 delay time 建議大於 33T(33 倍的 RA8815 system clock
cycle), delay time 的建議值為大於 0.7mS
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