RAiO
RA8806
Two Layers
Character/Graphic
LCD Controller
FAQ
Preliminary Version 1.0
June 24, 2009
RAiO Technology Inc.
©Copyright RAiO Technology Inc. 2009
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
Update History
Version
1.0
Date
June 24, 2009
RAiO TECHNOLOGY INC.
Description
Preliminary Version
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RA8806
Preliminary Version 1.0
Chapter
Two Layers Character/Graphic LCD Controller
Contents
Page
1. General Functions .................................................................................... 5
1-1 Basic Functions Introduction.............................................................................. 5
1-2 How to Design RA8806 Application Circuit on LCM ? ...................................... 6
1-3 Fail to Display on by RA8806 .............................................................................. 7
1-4 How to Display Text on LCD ? ............................................................................ 8
1-5 How to Use 「Continuous-Data-Writing」Function ? ....................................... 8
1-6 How to Adjust the Frame Rate ? ....................................................................... 10
1-7 Frame Rate Setting Between Gray Scale Mode and Monochrom Mode ........ 10
1-8 Contrast Adjustment to Improve the Display Quality ..................................... 10
2. Eliminating Flicker Mode ....................................................................... 11
2-1 What is “Flicker”? .............................................................................................. 11
2-2 The Limits in Eliminating Flicker Mode ............................................................ 11
2-3 The Recommendations when Using Eliminating Flicker Mode...................... 11
3. Touch Panel Mode.................................................................................. 12
3-1 How to Use RA8806 Embedded Touch Panel Controller ? ............................. 12
3-2 The Difference between Manual Mode and Auto Mode................................... 13
3-3 How to Detect Touch Event ?............................................................................ 13
3-4 The Settings with Flowchart in Auto Mode ...................................................... 13
3-5 The Settings with Flowchart in Manual Mode.................................................. 15
4. Gray Scale Mode .................................................................................... 18
4-1 RA8806 Gray Scale Application and Characteristic ........................................ 18
4-2 The Required Memory in 320x240 Gray Scale Image...................................... 18
4-3 How to Display a 320x240 Gray Scale Image?................................................. 18
4-4 How to Display a 240x160 Gray Scale Image at Coordinate (5,5) ? ............... 18
4-5 How to Display Text or Symbol in Gray Scale Mode?..................................... 19
5. Other Technical Questions.................................................................... 20
5-1 Missing Display Dot when Display Text or Image ........................................... 20
5-2 Text Shift or Image Shift .................................................................................... 20
5-3 How to Prevent the Crash Occurred ?.............................................................. 20
5-4 How to Prevent the IC Damage ? ...................................................................... 21
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
5-5 Display Performance with“Crosstalk”or Bad Quality ..................................... 21
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
1. General Functions
1-1 Basic Functions Introduction
RA8806 is a strong and easy to use STN LCD controller.Additionally, excepting the STN LCD
display functions, it also contains the function of BIG5 (or GB) and ASCII font ROM、smart ADC
touch controller and smart key-scan controller. Users can save lots of time and cost on system
hardware and software development. The system block diagram of RA8806 as below for the
reference:
LCD
LCD
Driver
Driver
Font
ROM
Display
RAM
CPU
CPU
1
2
3
4
5
6
7
8
9
*
0
#
LCD
LCD Panel
Panel
LCD
LCD
Driver
Driver
LCD
Controller
(128x64
(128x64 ~~ 640x240)
640x240)
Touch Panel
ADC
Key-Scan
Touch
Controller
RA8806
Figure 1-1
Basically RA8806 accepts commands from MCU then send the data that what RA8806 received
from MCU to LCD driver and via the connection between LCD drivers and STN LCD to display
texts or images on the screen. Therefore, RA8806 is the control IC between MCU and LCD driver.
There are two modes in real application:One is designed RA8806 on LCD modules that become
LCD modules are embedded with RA8806 controller and please refer the block diagram as below:
LCD 模組
其他元件
其他元件
升壓電路
升壓電路
LCD
LCD
Driver
Driver
LCD
LCD
Controller
Controller
CPU
CPU
LCD
LCD
Driver
Driver
LCD
LCD Panel
Panel
(128x64
(128x64 ~~ 640x240)
640x240)
RA8806
Figure 1-2
Another one is designed RA8806 on the system side to collocate various LCD modules that
without controllers and please refer the block diagram as below:
LCD 模組
其他元件
其他元件
CPU
CPU
升壓電路
升壓電路
LCD
LCD
Driver
Driver
LCD
LCD
Driver
Driver
LCD
LCD
Controller
Controller
LCD
LCD Panel
Panel
(128x64
(128x64 ~~ 640x240)
640x240)
RA8806
Figure 1-3
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
1-2
-2 How to Design RA8806 Application Circuit on LCM ?
If you were LCM suppliers and who wants to designed RA8806 on LCD modules with LCD
controller, please download the latest RA8806 datasheet first. For the complete RA8806 datasheet,
you could contact with our agent or directly log on to our website ((www.raio.com.tw).
www.raio.com.tw). Before you
designing your application circuit, please refer RA8806 datasheet pin definition、description of
LCD driver interface in section 6-2 and the reference application circuit in appendix A. We
especially highlight some common oversight points as below to be noticed:
There is a bit different application circuit design between 3V LCM and 5V LCM,
please refer to section 6-7 of RA8806 datasheet.
When RA8806 is operating in 5V system, users must connect capacitor 1µF and
0.1µF between VDD to the ground for the VDD stability. The reference figure as
below or refer to section 6-7-3 of RA8806 datasheet.
5V
MCU
RA8806
5V
VDDP
VDD
~3V
VDD
VDDH
0.47uH
AVDD
GNDP
(Option)
10u 0.1u
1u 0.1u
GND
0.1u
AGND
GND
I/O
MCU I/F
Figure 1-4
RA8806 oscillator circuit is generated by external crystal and two capacitors which
are between XG and XD pins. We suggest the crystal range is from 4MHz to 12MHz
(even though RA8806 is pin to pin compatible with RA8803/RA8822 but the crystal of
RA8803/RA8822 is fixed to 32768Hz, totally different with RA8806). The reference
figure as below:
RA8806
XG
15pF
X’tal
XD
15pF (4~12MHz)
Figure 1-5
RA8806 supports 8080 and 6800 interface modes and pin “MI” defines which
interface is going to use (MI:0 Æ 8080 interface；MI:1 Æ 6800 interface). User’s
software protocol must follow the hardware setting to make sure RA8806 receive
correct commands from MCU.
Due to it is unpredictable what environment the system developer is using in, so we
strongly recommend the users to connect a capacitor 50~150pF between ZCS1、
ZRD and ZWR to the ground. Please refer the figure below or figure 6-1、6-2 of
RA8806 datasheet.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
8080
MPU
RA8806
A0
A1-A7
IORQ
RS
ZCS1
Decoder
CS2
MI
D0-D3(D0 -D7)
DATA0-3(DATA0-7)
RD
ZRD
WR
ZWR
RES
ZRST
Figure 1-6
To use touch panel function, users except connect XL、XR、YU and YD to RA8806
who still need to connect capacitor 0.01µF with these 4 wires to the ground and a
pull-high resistor 39Kohm to pin YU. Please refer the figure below or figure 6-18 of
RA8806 datasheet.
VDD
RA8806
39Kohm
X1
Touch Panel
XL
X2
XR
Y1
YU
Y2
YD
0.01μF x 4
Figure 1-7
Besides RA8806, LCM designers must make sure other devices and circuits correct, like booster
circuit、OP bias circuit and LCD driver circuit. For LCM designers or system developers, it is
available to refer our sample program and download directly from RAiO website
(www.raio.com.tw). We provide two sample programs of 320x240 and which are
RA8806_320x240-EX1.rar and RA8806_320x240-EX2.rar.
1-3 Fail to Display on by RA8806
If you were LCM suppliers, below are the debug and analyze steps when fail to display on LCD by
RA8806 :
1. Make sure the power(3V or 5V) is correct supplying to RA8806、booster circuit、OP
bias circuit and LCD driver circuit.
2. Make sure VLCD (which is generated by booster circuit) and V0~V4(which are
generated by OP bias circuit) are correct supplying to LCD driver.
3. Make sure RA8806 oscillator circuit is operating correctly. Users could measure pin XD
and pin XG by oscilloscope to check the oscillating is happened or not.
4. Make sure RA8806 ZRST receive the reset signal from MCU during the power on. After
reset, ZRST should keep at Hi level.
5. Make sure RA8806 hardware connection and pin definition are correctly connecting with
MCU.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
6. Make sure the timing is generated from MCU that matches with RA8806 requirement
and hardware settings are the same with RA8806 modules. Please refer to figure 6-3、
6-4 of RA8806 datasheet.
7. Make sure the commands are generated from MCU that match with RA8806 setting
steps and requirement.
8. Make sure the signals (YD、FR、LP、XCK、LD[3:0]) to LCD driver are generated
correctly.
Assume the signals to LCD driver are generated correctly, the LCD should be displayed on. If the
LCD fails to display on, normally reason is the booster circuit. It is either no VLCD generating by
booster circuit or V0~V4 from OP bias circuit are not correctly supplying to LCD driver.
If you were system developers, the modules you get that usually after the test by LCM suppliers.
So if users fail to display on by RA8806, normally reasons are as item 5~7 above. If users design
RA8806 on the system side to collocate various LCD modules that without controllers, then must
check straight item 3~8 as above.
1-4 How to Display Text on LCD ?
For writing data into Display Memory to display texts or images on LCD screen, users need to
send memory write command (0xB0) first before the display data write to avoid the failure display.
The register [00h] bit-3 is defined which mode is in using : 1Æ text mode ; 0 Æ graphic mode.
For example : show letter A on LCD screen
LCD_Text();
LCD_CmdWrite(0xB0)；
LCD_DataWrite(0x41)；
// set the Register [00h] Bit3 to 1
// Character Code of A (Font Code) is 41h
1-5 How to Use 「Continuous-Data-Writing」Function ?
RA8806 supports “Continuous-data-writing” function. Users can continuous write text-data or
image-data into memory after the coordinate and memory write command (0xB0) set.
For example : show letters ABC on LCD screen
LCD_Text();
LCD_SetXY(5,10)；
LCD_CmdWrite(0xB0)；
LCD_DataWrite(0x41)；
LCD_DataWrite(0x42)；
LCD_DataWrite(0x43)；
// set the Register [00h] Bit3 to 1
// set address X = 5，Y = 10
// Font Code A : 41h
// Font Code B : 42h
// Font Code C : 43h
Please note that the memory write command (0xB0) must re-send when other commands are
executing during the continuous data writing. Users usually forget to re-send memory write
command (0xB0) after setting display data in another coordinate. And it will cause the afterward
display data fail to display.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
For example: show letters ABCDE at coordinate(0,0) on LCD screen
ABCDE
ABCDE
Figure 1-8
Common incorrect setting :
LCD_Text();
// set the Register [00h] Bit3 to 1
LCD_SetXY(0,0)；
// set address X = 0，Y = 0
LCD_CmdWrite(0xB0)；
for(i = 0 ; i < 5 ; i++)
{
LCD_DataWrite(0 x 41 + i)；// data write : ABCDE
}
LCD_SetXY(0,16)；
// set address X = 0，Y = 16
for(i = 0 ; i < 5 ; i++)
{
LCD_DataWrite(0 x 41 + i)；// data write : ABCDE
}
The incorrect setting above will cause the second line ABCDE fail to display. As the memory write
command (0xB0) re-send after the coordinate set, the situation is solved.
Correct setting :
LCD_Text();
// set the Register [00h] Bit3 to 1
LCD_SetXY(0,16)；
// set address X = 0，Y = 16
LCD_CmdWrite(0xB0)；
for(i = 0 ; i < 5 ; i++)
{
LCD_DataWrite(0x41 + i)； // continue write ABCDE
}
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
1-6 How to Adjust the Frame Rate ?
RA8806 provides a register ITCR (Idle Time Counter Register) for users adjusting the frame
rate.The ITCR is used to determine every LCD COM scan time.Please refer the figure below :
XCLK
LP
COM_SCAN
ITCR
T_COM
Figure 1-9
Assume the panel resolution is 320x240 and driver data bus is 4-Bit, the formulate between the
frame rate and ITCR as below :
Frame Rate =
System Freq.
( ITCR +320 / 4 ) × 240
For example:what ITCR will be if the system clock is 4 MHz and frame rate is 70Hz ?
ITCR =
4 × 10
6
240 × 70
− 80 = 158
1-7 Frame Rate Setting Between Gray Scale Mode and Monochrom Mode
The frame rate is different in gray scale mode and monochrom mode. For the best display
performance, we suggest the frame rate is set to 70Hz in monochrom mode and 120Hz ~ 140Hz
in gray scale mode to avoid the flickering.
1-8 Contrast Adjustment to Improve the Display Quality
After the contrast adjustment,the display quality is still poor and dark.It usually related to the frame
rate.When the frame rate ＞ 90Hz in monochrom mode,the display quality is getting worst. For the
similar issues, users must adjust the frame rate between 70Hz ~ 80Hz. Regarding to the frame
rate in different system clock, users could refer appendix B of RA8806 datasheet.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
2. Eliminating Flicker Mode
2-1 What is “Flicker”?
The flicker means when RA8806 internal logic circuit is doing the scan task, at the meantime MPU
is doing the data access to RA8806 DDRAM.The error will be occurred by the interfering scan
data and it will cause unexpected flicker. RA8806 embedded eliminating flicker function, users
only need to set the register MISC [01h] bit-7 to 1 to enable this function.
2-2 The Limits in Eliminating Flicker Mode
The eliminating flicker function is not available in text mode and memory clear mode. It is
available only in graphic mode.
Memory clear means the data is going to be set (ex : to clear the screen is set to 0x00) into the
register PNTR[E0h], enable this function and the screen will be automatically clear by
hardware.
While switching the text/graphic mode, users must beware of the eliminating flicker function is
active or not, because it will effect the display performance.
2-3 The Recommendations when Using Eliminating Flicker Mode
Users could have the better display performance who is following recommendations when using
eliminating flicker mode.
Disable eliminating flicker function in text mode.
Enable eliminating flicker function in graphic mode.
Disable eliminating flicker function before to active memory clear function and enable
eliminating flicker function after the screen clear is done by memory clear function.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
3. Touch Panel Mode
3-1 How to Use RA8806 Embedded Touch Panel Controller ?
Hardware control :
Users only need to connect the touch panel control pins – XL、XR、YU and YD to RA8806.
For the stable signal output, we suggest to connect capacitor 0.01uF between each control
pins (XL、XR、YU and YD) and ground. Please refer the figure below :
VDD
RA8806
39Kohm
Touch Panel
X1
XL
X2
XR
Y1
YU
Y2
YD
0.01μF x 4
Figure 3-1
Software control :
Register TPCR1 [C0h] bit-7 to enable touch panel function then users could depend on what
application you need to choose the related functions :
Table 3-1
Reg.
Bit_Num
Description
Reference
TPCR1
Bit 7
Enable Touch Panel function
REG[C0h]
Bit 7
“Auto-Mode” or “Manual Mode” selection bit
Bit 1~0
Mode selection for TP manual mode
Bit 4
Touch Panel Hardware Interrupt enable bit.
TPCR2
INTR
Bit 3
Touch event detect bit
( use in Manual Mode only).
REG[C4h]
REG[0Fh]
Bit 0
Touch Panel Detect Status bit
TPXR
Bit 7~0
Touch Panel X Data Bit [9:2] (Segment)
REG[C1h]
TPYR
Bit 7~0
Touch Panel Y Data Bit [9:2] (Common)
REG[C2h]
Bit 3~2
Touch Panel Y Data Bit [1:0]. (Common)
Bit 1~0
Touch Panel X Data Bit [1:0]. (Segment)
TPZR
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REG[C3h]
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
3-2 The Difference between Manual Mode and Auto Mode
The manual mode means that whole process from detect touch event to latch X、Y data and
read X、Y coordinate is finished by software engineer in manual mode.
When enable touch panel function in auto mode, users do not need to do anything till the touch
event happen and the X、Y coordinate will be automatically read.
The advantage of auto mode is easy to use and manual mode is much flexible for users.
3-3 How to Detect Touch Event ?
Users could detect the touch event by external interrupt or polling touch status. Description as
below :
(一)
Detect by external interrupt :
By hardware, users must connect RA8806 interrupt pin to MCU interrupt input pin.
By software, users must enable register INTR[0Fh] bit-4 to detect the touch event happen.
When detect the touch event happen, RA8806 will send interrupt signal to MCU.
The program will jump to ISR(interrupt service routine).
Executing corresponding functions.
(二)
Detect by polling touch status :
Polling touch status means that keep checking register INTR[0Fh] bit-0 to detect there is
touch event happened or not.
When detect touch event happen, register INTR[0Fh] bit-0 will be set to 1 and after XY
coordinate read、corresponding functions are finished, users must clear this bit to 0 to
detect the next touch event happen.
3-4 The Settings with Flowchart in Auto Mode
(一) The required settings in auto mode as following table (symbol * means required settings,
others are depend on applications)
Table 3-2
Reg.
Bit_Num
Bit 7
TPCR1
TPCR2
INTR
Description
Reg._Num
Enable Touch Panel function
Bit 6~4
Touch scan sampling time adjust bit
Bit 2~0
Touch scan frequency conversion speed bit
Bit 7
“Auto Mode” or “Manual Mode” selection bit
Bit 4
Touch Panel Hardware Interrupt bit
Bit 0
Touch Panel Detect Status bit
＊
REG[C0h]
＊
＊
REG[C4h]
＊
REG[0Fh]
Note: For detail descriptions, please refer to page 18 、27、28 of RA8806 datasheet.
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
In above table, there is the specific rule between touch scan sampling time and touch scan
frequency conversion speed from register TPCR1[C0h]. For the stable ADC output coordinate,
please follow the recommendations as the table below :
Table 3-3
System
CLK
4 MHz
6 MHz
8 MHz
10 MHz
12 MHz
ADC
Conversion
Clock Control
REG[C0][2:0]
000
001
010
000
001
010
011
100
000
001
010
011
100
000
001
010
011
100
000
001
010
011
100
Conversion
Frequency
(KHz)
1000
500
250
1500
750
375
188
94
2000
1000
500
250
125
2500
1250
625
313
156
3000
1500
750
375
188
Touch scan
Sampling wait
time
REG[C0][6:4]
000
000
000
000
000
000
001
010
000
000
000
001
010
000
000
000
001
010
000
000
000
001
010
Sampling
wait time
REG[C0]
Suggested
data
50
50
50
50
50
50
100
200
50
50
50
50
100
50
50
50
50
100
50
50
50
50
100
0x80
0x81
0x82
0x80
0x81
0x82
0x93
0xA4
0x80
0x81
0x82
0x83
0x94
0x80
0x81
0x82
0x83
0x94
0x80
0x81
0x82
0x83
0x94
Note: The above recommendations are not 100% guarantee users will get the stable ADC
output coordinate under the different touch panel modules or indefinite touch status (ex: tap).
And this is still needed the users to enhance by the program.
(一) There are three steps to be followed in auto mode
(1) Define the parameters(included choosing auto mode、enable touch panel function、touch
scan sampling time、touch scan frequency conversion speed and other settings)
(2) Detect touch event (included external interrupt and polling touch status, please refer to
FAQ item 3-3 description)
(3) Read X,Y coordinate (there are 10-bit each of X 、 Y and which is separate in
register[C1h]、[C2h] and [C3h], please refer to FAQ item 3-1 description)
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
The flowchart as below is using external interrupt in auto mode :
Start
Enable Touch Panel
ISR
( REG[C0h] B7 = 1 )
Set Auto Mode
Check INT Status
( REG[C4h] B7 = 0 )
0
( REG[0Fh] B0 = ? )
1
Enable TP INT Mask
( REG[0Fh] B4 = 1 )
Read X, Y-axis
( Read REG[C1h],
Ext. INT Event
REG[C2h], REG[C3h] )
Execute Function
Other Functions
Clear TP INT Status
( REG[0Fh] B0 = 0 )
ISR Termination
Figure 3-2
3-5 The Settings with Flowchart in Manual Mode
The required settings in manual mode as following table (symbol * means required settings, others
are depend on applications)
Table 3-4
Reg.
Bit_Num
Bit 7
TPCR1
TPCR2
Touch scan sampling time adjust bit
Bit 2~0
Touch scan frequency conversion speed bit
Bit 7
Bit 1~0
Bit 3
Bit 0
Reference
Enable Touch Panel function
Bit 6~4
Bit 4
INTR
Description
TP Manual mode enable
Mode selection for TP manual mode
＊
REG[C0h]
REG[C4h]
＊
＊
Touch Panel Interrupt Mask
Touch Panel Detect Status bit (use in manual
mode only).
REG[0Fh]
Touch Panel Detect status bit
Note: For detail descriptions, please refer to page 18 、27、28 of RA8806 datasheet.
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Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
There are six steps to be followed by polling touch status in manual mode :
(1) Define the parameters (included choosing manual mode、enable touch panel function and
other settings).
(2) Set register TPCR2[C4h] bit[1:0]=01 to wait touch event.
(3) Check the touch event is the valid touch or not (it will be treated as the valid touch if
register INTR[0Fh] bit-3 always equal the same value in enough checking times).Latch X
data in manual mode (it means set register TPCR2[1:0]=10b and wait enough time for the
stable data latch).(*)
(4) Latch Y data in manual mode (it means set register TPCR2[1:0]=11b and wait enough time
for the stable data latch).(*)
(5) Read X,Y coordinate (there are 10-bit each of X 、 Y and which is separate in
register[C1h]、[C2h] and [C3h], please refer to FAQ item 3-1 description)
(*)We suggest the waiting time at least equal to 50 ADC clock and ADC clock conversion
speed is depend on register TPCR1[C0h] bit[2:0]. Now we assume system clock is 4MHz
and there is the reference table as below of register TPCR1[C0h] bit[2:0] with the
different settings
Table 3-5
REG[C0h][2:0]
ADC clock
conversion
speed
ADC clock
cycle
suggested wait
time
（50 ADC Clock）
000
1 MHz
1 μs
50 μs
001
500 KHz
2 μs
100 μs
010
250 KHz
4 μs
200 μs
011
125 KHz
8 μs
400 μs
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
The flowchart as below is using polling touch status in manual mode :
Start
Enable Touch Panel
Latch X Data
( REG[C0h] B7 = 1 )
( REG[C4h][1:0] = 10 )
Set Auto Mode
Delay enough time
( REG[C4h] B7 = 1 )
Latch Y Data
Wait for TP event Mode
( REG[C4h][1:0] = 11 )
( REG[C4h][1:0] = 01 )
Delay enough time
Check TP Event
0
Read X, Y-axis
( REG[0Fh] B3 = ? )
( Read REG[C1h],
1
REG[C2h], REG[C3h] )
Check TP Event
valid
Execute Function
100 times ?
invalid
Clear TP INT Status
( REG[0Fh] B0 = 0 )
Other Function
Figure 3-3
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RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
4. Gray Scale Mode
4-1 RA8806 Gray Scale Application and Characteristic
RA8806 supports 4-gray-scale display.
To perform the gray scale that the users only need to set register MAMR[12h] bit[6:4] to 000b.
RA8806 supports 4-gray-scale function in images display and texts display. Regarding the
texts display, please refer to FAQ item 4-5 description.
4-2 The Required Memory in 320x240 Gray Scale Image
In gray scale mode, each display pixel needs 2 bits memory space to save into. For example: How
many display memory spaces are going to use if the display image is 320x240 ?
320 x 240 x 2 = 153600 bits = 19200 bytes (about 19K bytes)
4-3 How to Display a 320x240 Gray Scale Image?
Users must enable gray scale mode first (it means to set register MAMR[12h] bit[6:4] to 000b) then
write the image data into display memory from coordinate(0,0). Below is the sample program for
the reference :
LCD_GrayScale_Mode()；
// enable gray scale function
// set coordinate at X = 0，Y = 0
LCD_SetXY(0,0)；
// memory write command
LCD_CmdWrite(0xB0)；
for(i = 0 ; i < 19200 ; i ++)
// write data 19200 bytes
{
LCD_DataWrite(320x240_Gray_pic[ i ])；
}
4-4 How to Display a 240x160 Gray Scale Image at Coordinate (5,5) ?
Now if the active window is setting to 320x240；users need to write total 160 rows and 60 bytes
per row(240*2/8) data into display memory by the program in double loop method. Due to it is
unable to change row automatically, users must re-send coordinate before per row starting to write
data. Sample program as below for the reference :
for(i = 0 ; i < 160 ; i ++)
// 160 rows
{
LCD_SetXY(5, 5 + i)；
// set coordinate at X = 5，Y = 5
// memory write command
LCD_CmdWrite(0xB0)；
for(j = 0 ; j < 60 ; j ++)
// 60 bytes per row data
{
LCD_DataWrite(240x160_Gray_pic[ j + i ＊ 60 ])；
}
}
RAiO TECHNOLOGY INC.
18/21
www.raio.com.tw
RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
4-5 How to Display Text or Symbol in Gray Scale Mode?
We provide two program codes for customer reference and which are rotate 90 degrees display
and normal(non-rotate) display applications. If the users want to perform the GB/BIG-5 fonts under
the gray scale mode, all you need is only to set related parameters in what program code you are
using of two program codes.
XX : X coordinate value of the text who want to display, the data length is 8 bits.
YY : Y coordinate value of the text who want to display, the data length is 8 bits.
*ptr : text strings pointer address, the data length is 8 bits.
gray_level : define the text gray scale.
font_inverse : font inverse function.
Users must note that there are two steps need to set befor using the program code :
Switch the display mode into gray scale mode.
Set Register WCCR[10h] bit-3 to 1 in rotate 90 degrees display application.
Sub-routine for displaying font
in the gray-scale mode
Main Program
Start
Reset LCD
Initialize LCD
Setup Display
Page1
Turn on LCD
Enable character
mode
Clear display
memory
Rotate 90° on the
screen
Setup RA8806 to
access Page1
Write a full-size font
on the specified
coordinate
Setup RA8806 to
display Page1
Setup graphic
input mode
Enable graphic
mode
Read 32 byte
display data from
RA8806
Enable gray-scale
mode
Enable gray-scale
mode
Enable Eliminating
flicker mode
Transfer the 32 byte read
back data and write them
into the display memory of
RA8806
Display 4-grayscale image
Show font on grayscale image
End
No
Is it the 32nd data ?
Yes
No
Is it the last font ?
End
RAiO TECHNOLOGY INC.
19/21
www.raio.com.tw
RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
5. Other Technical Questions
5-1 Missing Display Dot when Display Text or Image
There are two possibilities:
1. Unstable DC-DC from RA8806 Æ When RA8806 operates in 5V system (VDDP=5V), VDD
should connect a capacitor ＞1µF to the ground. Please refer section 6-7-3 of RA8806
datasheet.
2. MCU data access is too faster than RA8806 data process Æ Please add Delay into the
program or by check Busy to make sure RA8806 has already finished processing the last
data.
5-2 Text Shift or Image Shift
Here are four possibilities:
1. RA8806 display window setting and active window setting are different with LCD resolution.
The table below is listing the common LCD resolution with the related register settings for
the reference:
Table 5-1
Panel
Resolution
Segment Common
REG[21h]
DWWR
REG[31h]
DWHR
160*80
160
80
13h
4Fh
160*128
160
128
13h
7Fh
160*160
160
160
13h
9Fh
240*64
240
64
1Dh
3Fh
240*128
240
128
1Dh
7Fh
240*160
240
160
1Dh
9Fh
320*240
320
240
27h
EFh
2. MCU data transfer is too faster than RA8806 data process Æ Please add Delay into the
program or by check Busy to make sure RA8806 has already finished processing the last
data.
3. The timing is generated from MCU that not matches RA8806 requirement Æ To avoid
insufficient Set-up time or Hold time, please refer to figure 6-3、6-4 of RA8806 datasheet.
4. The text shift or image shift phenomenon could be caused by the bad system
environment 、serious noise effect or the long connection between module and system Æ
Even though RA8806 is using Schmitt Trigger on MCU input interface to avoid the noise
effect, but RA8806 still might work incorrectly by the serious noise effect. To reduce
connections between MCU and RA8806 effect or system environment effect, users could
connect a capacitor 50~150pF between ZCS1 、 ZRD and ZWR to the ground. If it is
caused by the MCU weak signal or the heavy loading, users could connect a pull-high
resistor 1K~4.7Kohm on ZCS1、ZRD 、ZWR and DATA[7:0].
5-3 How to Prevent the Crash Occurred ?
The possible reasons are because the bad system environment and serious noise effect Æ Please
refer to item 4 of the previous section 5-2. Besides, please avoid the long connection between
module and system.
RAiO TECHNOLOGY INC.
20/21
www.raio.com.tw
RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
5-4 How to Prevent the IC Damage ?
RA8806 ESD protection could reach to ±8KV, it is much higher than industrial standard 4KV
requirement. But users still must especially notice the PCB layout and add the protection devices
to avoid the IC damage for the special and bad system environment usage.
And the too high sudden power pulse or supply over 5.5V voltage for a long time will cause the IC
damage as well Æ Users could connect a capacitor 470µF or the surge absorber between VDD to
the ground to avoid the IC or LCM damage.
Power
LCD Module
7V
VDD
6V
5V
Driver
470uF
Driver
Driver
RA8806
Driver
Driver
GND
t
Time
Figure 5-1
Another reason will cause the IC damage is because the EOS(Electrically Over Stress). The better
way to avoid it is to reduce the cable length as short as possible or connect a resistor
200ohm~1Kohm between the system and LCMs.
System Board
LCD Module
MCU
:
:
:
Driver
Driver
Driver
RA8806
Driver
Driver
Figure 5-2
5-5 Display Performance with“Crosstalk”or Bad Quality
There are four possibilities:
1. LC quality or polarizer is poor.
2. Booster ability (VLCD) or driving ability is insufficient.
3. Incorrect bias (V0~V4).
RA8806 frame rate setting is too high to cause the crosstalk or bad display quality. Please
refer to frame rate setting table in appendix B of RA8806 datasheet. The ITCR[90h] setting
is defined by what LCD resolution in using and system clock. Too high frame rate will
cause the driver with the high power consumption and then effect the booster ability (VLCD)
or driving ability is insufficient.
RAiO TECHNOLOGY INC.
21/21
www.raio.com.tw