Display

Transcrição

Display

ET/IT & TI
Electronic Displays
Design and Driving
of Embedded
Displays Systems
Karlheinz Blankenbach
Pforzheim University, Germany
Prof. Dr. Karlheinz Blankenbach
Phone : +49 7231 - 28 - 6658
Pforzheim University
Fax
Tiefenbronner Str. 65
Email : [email protected]
D-75175 Pforzheim, Germany
Web : www.displaylabor.de
: +49 7231 - 28 - 6060
1
Blankenbach / Pforzheim Univ. / www.displaylabor.de / ES Driving / Oct. 2008
ET/IT & TI
Electronic Displays
Overview
• Introduction
• Low resolution displays
• Graphics systems
• Miscellaneous
• Summary
Embedded PC, TV,
high resolution,
interfaces etc.
see other lecture
2
ET/IT & TI
Electronic Displays
Display Systems in Daily Life
… developed in Germany
Huge number of applications with different display driving and I/Fs !
3
ET/IT & TI
Electronic Displays
Definition of Embedded Systems in This Lecture
• µC … µP (4 – 32 Bit)
• Display: 8-Segment … VGA
• Indoor & outdoor use
• Typically in a housing
Display
controller
Display
µC or µP
(4 - 32 Bit)
Power
(battery or line)
Data to display set display resolution and,
in consequence, µC and display controller!
AD, DA, IO
knobs, keyboard
Sensors
Actuators
4
ET/IT & TI
Electronic Displays
High End Embedded System Hardware
Vision
Data
Display
controller
µC, µP
PC, TV
Display
Controller
Interface
& Timing
Controller
Driving
Principle
Electro-optic
Characteristic
Display
Glass
Focus of this talk in terms of a system
ET/IT & TI
5
Electronic Displays
Displays for Mobile Applications as a System
… only suitable for large volume mass production
‚Everything‘ is in an single IC !
6
ET/IT & TI
Electronic Displays
Character Design vs. Resolution
R G B
5
mm
Segment 8
# of Pixel
Starburst
101
102
Matrix 5x7
QVGA 10x15
103
104
XGA 10x15
105
106
‘here’
Driving of Module
µC
Display controller
‚PC‘
low
medium
high
Data Rate
Software Requirements
high w/o OS or Lib
minor
minor (OS)
ET/IT & TI
7
Electronic Displays
Embedded Display Systems Design (No Embedded PC)
• Size : 0.5‘‘ … 10.4‘‘
(> public displays)
• Pixel : 7 … millions (1x Segment8 … WXGA)
• Color : Monochrome - grey shade - area color - color - full color
• Lifetime : 2y … 20 y ; operating time 100 h … 20 y, storage time
• Environment : outdoor … indoor, stationary … mobile, …
• Pieces per year : 10 … millions
(e. g. high end measurement device … household appliances)
• Life cycle : replacement of subassemblies, supply chain, recycling, …
Focus to non-ePC systems developed in Europe !
8
ET/IT & TI
Electronic Displays
Low Cost, Low Information Content Displays
Characteristics
- 1 … ~1,000 pixel
- Often icons, numbers, …
- ‘Cheap’
- Direct drive, MUX or PM, 8 bit µC
- (rest depends on application)
Technologies
• LCD
• OLED
• LED
• VFD
• EL (no more MP)
• E-paper (samples in Europe)
9
ET/IT & TI
Electronic Displays
System Design : Microwave Oven With or Without Display
• Several options
in between
• End user
preference ?
Change to
summer
time ?
Start 7:00 ?
Low Cost
- Easy to use
- Limited functions
High End
- Complex HMI
- Many functions
10
ET/IT & TI
Electronic Displays
Embedded Systems with Graphic Displays
• Embedded Systems (16 - 32 bit)
- Lower resolution than PCs
µP bus
B/W STN
- Typically digital output,
analogue output good
for debugging
- Often with OS
- Often with
FPD
output
Analogue
output
graphic controllers
CSTN
Graphics controller
TFT
• Low Resolution b/w
- µC needs display controller
- Limited to about 240 x 128
ET/IT & TI
11
Electronic Displays
Other Embedded Systems with Graphic Displays
• Panel PC
- ePC e.g. mounted on display
- Easy to integrate into systems
Just for reference because
of COTS systems !
• Serial Interfacing
- Easy interfacing via RS232, USB or 8-Bit
- 8 Bit µC can ‘drive’ up to XGA
- USB up to QVGA video stream
- Suitable for low volume and if
only low computing power is required
12
ET/IT & TI
Electronic Displays
7 Action Steps acc. Donald Norman
Human Action Cycle
Forming a goal
What happened ↔ what was intended
Translate goal to task(s)
Planning the action (sequence)
Interpreting the outcome
Perceiving what happened
Executing the action (sequence)
Adapted from D. Norman :
"The Design of Everyday
Things”, Basic Books,1988
13
ET/IT & TI
Electronic Displays
Easier Handling by Use of Innovative Display Systems
Status indicator
Cheap but often complex,
selection via pushbuttons
Software based pushbuttons
(soft keys) allow multiple
functions on one button
(see also mobile phones)
Touch screen
for intuitive
user action
Ergonomics
&
Price
14
ET/IT & TI
Electronic Displays
Style Guide for Low Res Embedded Display Systems
Negative mode
Positive mode
Status
Figures
Size
Characters
Resolution
Display
Graphics (fonts, icons)
Grey scale
requirements
Color
User guidance / Manual
System speed
Movie
Comfort
Ergonomics and price rise in parallel !
End user value and price-performance ratio also ?
Price
ET/IT & TI
Perceived Value
15
Electronic Displays
Design ↔ Price ?
Perceived value ↔ Customer sees benefit ?
• Display quality
Technology, size, resolution, color (depth), contrast, reflections,
temperature range, luminance, dimming, comparison to next
‘reference‘ (nearby displays like mobile phone, laptop etc.), …
• Ergonomics
Position in device, posture while looking, viewing distance,
reachability of controls, same mode all over device incl. prints, …
• Recognisability
Font, font size, graphics etc. set the display size
Observer angle, reflections of ambient light, …
• Screen Design
Way how to visualize the information, menu structure, controls, …
• Integration
Bezel (form, color, material), transition display-bezel-device,
display in off-state (color, immersible, fold-away etc.), …
16
ET/IT & TI
Electronic Displays
Screen Modes : Display - Device
Different frames
Contact pins visible
Different mode
Same
mode for
???
display
and text
(‚good‘)
No light for dark
Non-uniform illumination
White foreground green display color
Different
mode for
What‘s about a black background
surrounded by white (also off mode) ?
∆Emax !
display
and text
(‚bad‘)
Green foreground –
similar to display color
What is really recognized and
perceived by the customer ?
ET/IT & TI
Electronic Displays
Innovative Hob (Cook Top)
‚Old‘
17
Handling || Cook Top
‚New‘
Handling
⊥
Cook Top
18
ET/IT & TI
Electronic Displays
What is a Display Driver (System) ?
Row & column drivers
Interface
Display controller
↔ display
EOC
Matrix
TCON
Interface
µC ↔ display controller
µC
Display controller
Signal processing
19
ET/IT & TI
Electronic Displays
What is a Display Driver ?
A data to e-o converter
But there are different types :
• Display controller
(digital ‘image’ data → interface data)
Here
• Interface & timing controller
(interface data → driving principle, here FPD)
• Row driver
(row selection for matrix drive)
• Column driver
(data to display → grey level → EOC)
µC, µP
PC, TV
Display
Controller
Interface
& Timing
Controller
Driving
Principle
Electro-optic
Characteristic
Display
Glass
20
ET/IT & TI
Electronic Displays
Bill of Material for a Display Panel
Example for 10.4" VGA Color AM LCD
Polarizer etc.
Misc.
TFT plate
Backlight
Same price
Controller
Color filter
Driver ICs
Controller & driver ICs are about 25% (as color filter and TFT plate) !
21
ET/IT & TI
Electronic Displays
Display Controller Overview
Size, price, …
Driving within display
Direct drive MUX
Passive Matrix
MLA
Active Matrix
Resolution
µC, µP
PC, TV
Display
Controller
Interface
& Timing
Controller
Driving
Principle
Electro-optic
Characteristic
Display
Glass
22
ET/IT & TI
Electronic Displays
Comparison Direct - , Mux - and Matrix Drive
Matrix Drive
Direct Drive & Mux
ITO wire
Icon,
Pixel
A Dot shape
Number
of pixels
Example
Icons and/or Segment 8
Square or rectangle
Low (< 1,000)
High (... millions)
Watch, calculator,
Lap-
remote control
top
23
ET/IT & TI
Electronic Displays
System Aspects of Direct - , Mux - and Matrix Drive
Direct Drive & Mux
Matrix Drive
Application
specific
HW Layout (ITO),
Standard or customized
SW
Change in
specification
Expensive
Inexpensive
Icons
++ (small and sharp)
*
Numbers
+
*
Characters
-
*
Graphics
-
*
* Pixelated
for low
resolution
and/or ppi
LC-displays of cordless phones,
calculators etc. have often both
24
ET/IT & TI
Electronic Displays
Summary of Introduction
• Data to display should be the starting point for embedded display systems
• Display resolution determines controller and user interface
• Low information content displays can be optimized for perceived value
• High resolution and low volume systems often base on COTS ePCs
• Display driving has many topics like interfacing, …
Displays are the key component
in terms of price and user interface!
25
ET/IT & TI
Electronic Displays
Overview
• Introduction
• Low resolution displays
• Graphics systems
• Miscellaneous
• Summary
Embedded PC, TV,
high resolution,
interfaces etc.
see other lecture
26
ET/IT & TI
Electronic Displays
Overview : Low Resolution Driving
Examples for
LCD, other
technologies
similar
Data to
• Direct (µC - I/O)
µC
I/O
display
Seg
• Character Controller
µC
HD 44780
Com
RAM built in, no load for µC
• Graphics Controller
µC
Column
Driver
T 6963
Seg
Row
Driver
RAM
Module
ET/IT & TI
27
Electronic Displays
Issues for Driving of Displays (Non-PC)
• Direct (µC - I/O)
+ No additional IC etc.
+ Easy
- Only lowest ‘resolution’
- SW easy but every segment has to be set
• Character & Graphics Controller with Built-in RAM
+ Minor SW because of e.g. character generator
+ No load on µC, ‘no’ timing issues
- Only up to mid resolution (240 x 128), some QVGA available
• Graphics Displays (≥
≥ QVGA, color)
+ High resolution
+ Some high end µC with built-in display support
- Huge timing issues
- Real time display driving to avoid failures
- No support for pixel and graphics (use libs or OS)
28
ET/IT & TI
Electronic Displays
Proposals for Student Projects (I) 50+/-% software & hardware
• 8-Bit µC like ADUC842
• Displays:
- 8-Seg.
- HD 44780
- T6963
VFD
Driver
Task: Built 3 demos each for other students with basic software
29
ET/IT & TI
Electronic Displays
Proposals for Student Projects (II)
50+/-% software & HW
• 8-Bit µC like ADUC842
• LEDs:
- RGB
- Matrix
Task: LED-based displays or animations
30
ET/IT & TI
Electronic Displays
Proposals for Student Projects (III)
50+/-% SW & HW
• ADUC842
• Low res. T6963 graphics controller
Task: Built example application with I/Os etc.
31
ET/IT & TI
Electronic Displays
Proposals for Student Projects (IV)
100% software
• 16-Bit µC
• TFT direct drive
• Emulator
• GNU C(++)
• SW lib for objects
(EMWIN)
Task: Evaluation of features by examples
32
ET/IT & TI
Electronic Displays
Proposals for Student Projects (V)
100% software
• FUJITSU 16-Bit µC
• AM OLED CQVGA
• Touch screen
• C-Examples
Task: Adapt SW form scratch to structure subs, make example
ET/IT & TI
33
Electronic Displays
Proposals for Student Projects (VI) 90% software, 10% LCD
• Automotive graphics IC
• Video input
• MS VISUAL C++
• PC based
• Analogue monitor output
Task: Evaluation of features by examples, adapt LCD
34
ET/IT & TI
Electronic Displays
Proposals for Student Projects (VII)
90% software, 10% HW
• Many ePCs have no display output
• Low res display for status etc.
Could be helpful
• Easiest way via SW output via USB
• Also for laptops with defective display
Task: Build display output for ePCs with USB-µC and low res display
ET/IT & TI
35
Electronic Displays
Proposals for Student Projects (VIII)
• Your idea
•…
x% software, y% hardware
Task: tbd
36
ET/IT & TI
Electronic Displays
Details see
‘LCD‘
Direct Drive LCD
VDD
A
Control input to
Exclusive OR gate
VSS
VDD
A
B
C
XOR
Segment
D
Osc input (clock) to
Exclusive OR gate
B VSS
180°phase shifted
output of Exclusive
OR gate
VDD
C
Common
VSS
VB - C
B-C=D
D
Resultant display
waveform measured
segment to common
plate
0
Pixel
Off
Pixel
On
Pixel
Off
Simple driving with XOR because of automatic inversion - just set pixel !
ET/IT & TI
37
Electronic Displays
Direct Drive for 8 - Segment LCD
EXOR
a
b
c
a
f
d
µC e
f
b
g
e
c
d
g
Common
crossover
Clock
Segment plate
Common plate
38
ET/IT & TI
Electronic Displays
Direct Drive for 8 - Segment LCD
Code example
' LED 8-Seg
a
f
define Anzeige BYTEPORT[1]
g
' Binary BIT 7 6 5 4 3 2 1 0
' Segment
b
e
hgf ed cb a
c
d
Point
39
ET/IT & TI
Electronic Displays
Direct Drive for 8 - Segment LCD with 4 Digits
Seg
1g 1f
1a 1b
2g 2f
2a 2b
3g 3f
3a 3b 4g 4f
4a 4b
Com
Seg
1e 1d
1c 1dp 2e 2d
2c 2dp 3e 3d
3c 3dp 4e 4d
4c 4dp
- 8 lines per digit
- 4 digits : 32 seg.
+ 1 common
33 lines
40
ET/IT & TI
Electronic Displays
MUX Drive for 8 - Segment VFD
Grid (Scan)
Multiplex driving via
VFD
Driver
scan of grids
Anode (data)
1G 2G 3G 4G
41
ET/IT & TI
Electronic Displays
MUX Drive for 8 - Segment VFD
Grid (Scan)
Anode (data)
'***** Segments **************
'PortNr.:
16 15 14 13 12 11 10 9
'BitNr.
7 6 5 4 3 2 1 0
'G1 – 4
- g f e d c b a
...
Anzeige = 0 ' Space out
GRID = 1
ein = 1
Looktab decoder, ein, Anzeige
Anzeige = 0 ' Space out
GRID = 2
zehn = 2
Looktab decoder, zehn, Anzeige
table decoder
&B00111111
&B00000110
&B01011011
`0
`1
`2
42
ET/IT & TI
Electronic Displays
Multiplex Drive for 8 - Segment LCD with 4 Digits
Seg A1
B1
A2
B2
A3
B3
A4
B4
Com
1
2
3
4
Multiplex also
- 2 seg per digit :
named as
- 4 digits : 8 seg
# of µC-IOs is also limiting !
- MUX
+ 4 common
- Duty
12 lines
≈ 35 % of direct drive
43
ET/IT & TI
Electronic Displays
Multiplex Drive Waveforms for 8 - Segment LCD (4 Digits)
Duty 1/4
- Complex waveforms
for COMMON and SEGMENT
- Frame inversion
- 4 voltages
→ Cannot be done by µC,
display controller
or LCD-µC needed !
Data
44
ET/IT & TI
Electronic Displays
µC with Built - in LCD Output
• Typical 96 segments and 4 commons
about 400 ‘pixel’
• Typically for 4 8-Segment digits + icons
• Other configurations possible
45
ET/IT & TI
Electronic Displays
Code Example For µC with LCD - Output
MUX 4 (see VFD)
~ 30 segments
46
ET/IT & TI
Electronic Displays
LED Matrix Driving
TTL
µC
Drives 4 digit
5 x 7 LED
47
ET/IT & TI
Electronic Displays
Character Controller HD 44780
2 lines with 20 characters
(font 5 x 7) + 2 icon lines
- 16 Rows
Display RAM
µC
- 40 Columns
Character generator
5 x VLCD
48
ET/IT & TI
Electronic Displays
HD 44780 Interfacing
• µC ↔ Controller
Scan
µC
Data
• Controller ↔ Display glass
Scan
Data
49
ET/IT & TI
Electronic Displays
HD 44780 Programming
No need to program fonts
Character Generator
...
PC : Character generation by OS
.
.
.
Instructions
50
ET/IT & TI
Electronic Displays
Example for HD 44780 Programming
Instruction
Initialisation
8 Bit interface,
RS RW D7 D6 D5 D4 D3 D2 D1 D0
0
0
0
0
1
1
0
0
0
0
3 x instruction
0
0
0
0
1
1
0
0
0
0
0
0
0
0
1
1
0
0
0
0
2 lines, 5 x 7
0
0
0
0
1
1
1
0
0
0
Display on
0
0
0
0
0
0
1
1
0
0
Display clear
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
1
0
0
1
0
0
0
1
1
0
Entry mode
Write character
‘F'
to LCD RAM
'ENABLE' pulse for valid data required
ET/IT & TI
51
Electronic Displays
Example for HD 44780 Programming (I)
' Initialisierung des Displays
' alle Ausgänge 0
en = 0
rw = 0
rs = 0
daten = 0
daten = 48 ' 0011 0000 ` 8-Bit IF
pulse en
daten = 48 ' 0011 0000
pulse en
daten = 48 ' 0011 0000
pulse en
pause 1
' Function set 0011 NF00 N: Zeilen N=1:2Z, 0:1Z F: Charakter 1:5*10Dots, 0:5*8D
daten = &B00111000 ' 2 Zeilen
pulse en
pause 1
52
ET/IT & TI
Electronic Displays
Example for HD 44780 Programming (II)
' Display on 0000 1100
daten = 12
pulse en
' Entry Mode set 0000 01 ID S
daten = 6
' 0000 0110
pulse en
ID:1 increment, ID:0 decrement S:1 Displayshift
' Display clear 0000 0001
daten = 1
pulse en
' Buchstaben (4 ab `F`) schreiben
rs = 1
for BU = 0 to 4
daten = 46 + BU
pulse en
next BU
ET/IT & TI
53
Electronic Displays
Example for HD 44780 Programming (III)
/***********************************************/
/* Funktion: disp_init
*/
/* Initialisierung des HD 44780
*/
/***********************************************/
void disp_init ( void )
{
RS = 0; R_W = 0; E = 0;
DB7 = 0; DB6 = 0;
DB5 = 1; DB4 = 1;
DB3 = 0; DB2 = 0;
DB1 = 0; DB0 = 0;
E = 1; _nop_(); E = 0;
wait( 500 );
E = 1; _nop_(); E = 0;
wait( 100 );
E = 1; _nop_(); E = 0;
wait( 50 );
put_char( FUNCTION_SET );
wait( 500 );
put_char( DISPLAY_OFF );
wait( 500 );
put_char( CLS );
wait( 500 );
put_char( ENTRY );
wait( 500 );
/* Initialisierungswert 30H an Ports */
/* Schreiben in Display-Controller */
/* warten > 4.1 ms */
/* wiederholtes Schreiben */
/* warten > 100us */
/* wiederholtes Schreiben */
/* warten > 4.1 ms */
/* warten > 4.1 ms */
/* warten > 4.1 ms */
/* warten > 4.1 ms */
}
54
ET/IT & TI
Electronic Displays
Example for HD 44780 Programming (IV)
/*********************************************************************/
/* Funktion: sendchar2disp
*/
/* Beschreibung: Sendet ein ASCII-Zeichen an das Display */
/*********************************************************************/
void sendchar2disp ( char s )
{
if ( (s != '\0') && (s != '\n') )
{
RS = DA;
/* An Display schreiben */
split = s;
DB7 = SPLIT_7; DB6 = SPLIT_6; DB5 = SPLIT_5; DB4= SPLIT_4;
E = 1; wait(100); E = 0;
wait(100);
RS = IN;
/* Einschreiben in Display-Controller */
/* RS = 0 */
}
if ( s == '\n' )
{
RS = IN; R_W = 0;
split = LF_ADR;
/* šbergabewert in bdata-Bereich legen */
E = 1; wait(100); E = 0;
wait(100);
/* Einschreiben in Display-Controller */
}
}
ET/IT & TI
55
Electronic Displays
Case Study for Low Res System (I)
Task: Design temperature capturing & display device
with warning on high temperatures
• Microcontroller : …
• Display
:…
• Warning
:…
• Power supply : …
56
ET/IT & TI
Electronic Displays
Case Study for Low Res System (II)
8-Seg
LCD
Character
LCD
Low Res
Graphics
LCD
8-Seg
LED
8 Seg
VFD
Warning
Power
consumption
Price
Advantage
Issues
ET/IT & TI
57
Electronic Displays
Case Study for Low Res System (III)
System: …
58
ET/IT & TI
Electronic Displays
Monochrome Graphics Controller & Drivers
Column
drivers
(SEG)
Row
64k
SRAM
Graphics
controller
driver
(COM)
Module connector
b/w QVGA LCD
ET/IT & TI
59
Electronic Displays
Graphics Controller HD 61830
Row (scan, common)
Clock
Max. resolution : 240 x 128,
black & white
µC
TTL
Column
serial (segment,
data)
60
ET/IT & TI
Electronic Displays
HD 61830 Interfacing
Serial
data
~ 13 pins
Clock
Column
Row
~ 10 pins
6 LCD
supply voltages
61
ET/IT & TI
Electronic Displays
Instructions for HD 61830 (Example)
Can be used as
Character
controller
or
Graphics
controller with
character generator
Graphics must be programmed pixel wise !
62
ET/IT & TI
Electronic Displays
Low Resolution Display with Graphics Controller & µC
~ 16 lines flex cable
TCON
for
64 x 64
8-Bit µC
Column
driver
Row
driver
ET/IT & TI
63
Electronic Displays
Low Res Graphics Controller T6963 (I)
64
ET/IT & TI
Electronic Displays
Low Res Graphics Controller T6963 (II)
ET/IT & TI
65
Electronic Displays
Low Res Graphics Controller T6963 (II)
66
ET/IT & TI
Electronic Displays
Low Res Graphics Controller T6963 (IV)
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ET/IT & TI
Electronic Displays
Example for T6963 (I)
//*********************************************************************************************************
// Displayinitialisierung
// Hier werden die Grundeinstellungen des Displays vorgenommen.
//*********************************************************************************************************
// Übergabewerte:
keine
// Rückgabewerte:
keine
//*********************************************************************************************************
void init_Display(void)
{
write_data2(TEXT_HOME_ADR);
// Set Text Home Address
write_cmd(SET_TEXT_HOME_ADR);
write_data2(TEXT_AREA);
write_cmd(SET_TEXT_AREA);
write_data2(GRAPHIC_HOME_ADR);
write_cmd(SET_GRAPHIC_HOME_ADR);
write_data2(GRAPHIC_AREA);
write_cmd(SET_GRAPHIC_AREA);
// Set Graphic Home Address
// Set Graphic Area
OR_MODE;
// Set Or Mode
BOTH_ON;
// Set Display Mode
clr_Display();
}
68
ET/IT & TI
Electronic Displays
Example for T6963 (II)
//*********************************************************************************************************
// Adresspointer setzen
// Setzt den Adresspointer auf die Stelle im RAM an der als nächstes geschrieben werden soll
//*********************************************************************************************************
// Übergabewerte:
adresse: unsigned int
(Adresse im RAM)
// Rückgabewerte:
keine
//*********************************************************************************************************
void set_ADP(unsigned int adresse)
// Adress Pointer Setzen
{
write_data2(adresse);
write_cmd(SET_ADR_POINTER);
}
//*********************************************************************************************************
// Kommando schreiben
// schickt einen Befehl an den Displaycontroller
//*********************************************************************************************************
// Übergabewerte:
command: unsigned char
(Controllerbefehl)
// Rückgabewerte:
keine
//*********************************************************************************************************
void write_cmd(unsigned char command)
{
status();
cmd = command;
}
ET/IT & TI
69
Electronic Displays
Example for T6963 (III)
//*********************************************************************************************************
// Kommando schreiben
// schickt einen Befehl an den Displaycontroller
//*********************************************************************************************************
// Übergabewerte:
command: unsigned char
(Controllerbefehl)
// Rückgabewerte:
keine
//*********************************************************************************************************
void write_cmd(unsigned char command)
{
status();
cmd = command;
}
//*********************************************************************************************************
// Daten schreiben
// schickt 1 Byte Daten an den Displaycontroller
//*********************************************************************************************************
// Übergabewerte:
daten: unsigned char
(1 Byte Daten)
// Rückgabewerte:
keine
//*********************************************************************************************************
void write_data(unsigned char daten)
{
status();
dat = daten;
}
70
ET/IT & TI
Electronic Displays
Example for T6963 (IV)
//*********************************************************************************************************
// Zeichen schreiben
// Gibt ein Zeichen auf dem Display aus
//*********************************************************************************************************
// Übergabewerte:
Zeichen: unsigned char (muß gültiger ASCII-Wert sein)
// Rückgabewerte:
keine
//*********************************************************************************************************
void set_char(unsigned char Zeichen)
{
Zeichen -=0x20;
// ASCII to Controller
if (Zeichen & 128) Zeichen=0x03; // Zeichen nicht ASCII dann # ausgeben
write_data(Zeichen);
write_cmd(DATA_WRITE_INC);
}
ET/IT & TI
71
Electronic Displays
Example for T6963 (V)
//*********************************************************************************************************
// Pixel setzen/rücksetzen
// setzt oder löscht ein Pixel
//*********************************************************************************************************
// Übergabewerte:
x,y: unsigned char (X-Y-Koordinaten)
//
set: unsigned char (0 für rücksetzen, 1 für setzen)
// Rückgabewerte:
keine
//*********************************************************************************************************
void pixel(unsigned char x, unsigned char y, unsigned char set)
{
set_ADP(xy_to_grRAM(x, y));
if (set==0)
//für reset
{
write_cmd(0xF0 | (5-(x%GRAPHIC_LENGTH)) );
// Bit Reset
}
else
{
write_cmd(0xF8 | (5-(x%GRAPHIC_LENGTH)) );
// Bit Set
}
}
72
ET/IT & TI
Electronic Displays
Advanced Graphics Controller
SOLOMON SSD 1780
- 104 x 80 x RGB x 4 Bit
- Advanced graphics programming
X1, Y1
fillcolor
Built in SW reduces µC load
and saves SW development
color
X2, Y2
73
ET/IT & TI
Electronic Displays
High Resolution Displays (≥
≥ QVGA, Non-PC)
• Graphics Displays (≥
≥ QVGA, color) [as before]
+ High resolution
+ Some high end µC with built-in display support
- Huge timing issues
- Real time display driving to avoid failures
- No support for pixel and graphics (use of libs or OS)
• Number of pixels for QVGA: 320 x 240 = 76,800 > 16 Bit no 8-Bit µC !
Same for color ≈ 140 KByte (2 Byte color [16 Bit] per pixel) !
• Data rate for CQVGA: 320 x 240 x 60 Frames/s x 2 Byte (color) ≈ 10 MHz
- Not achievable with many 16-Bit µC
- ‘Real time’ data output to display input (row and column data)
requires huge effort
Issue:
New 16 and 32 Bit µC with display output
High res displays
have LVDS input
74
ET/IT & TI
Electronic Displays
NXP ARM 9 with LCD Output
Color LCD Controller
The LH7A400’s LCD Controller is programmable to support up to 1,024 ×
768, 16-bit color LCD panels. It interfaces directly to STN, color STN, TFT,
AD-TFT, and HR-TFT panels.
Unlike other LCD controllers, the LH7A400’s LCD Controller incorporates the
timing conversion logic from TFT to HR- and AD-TFT, allowing a direct
interface to these panels and minimizing external chip count.
The Color LCD Controller features support for:
• Up to 1,024 × 768 Resolution
• 16-bit Video Bus
• STN, Color STN, AD-TFT, HR-TFT, TFT panels
• Single and Dual Scan STN panels
• Up to 15 Gray Shades
• Up to 64,000 Colors
ET/IT & TI
75
Electronic Displays
Block Diagram
76
ET/IT & TI
Electronic Displays
ET/IT & TI
77
Electronic Displays
Vertical Timing
78
ET/IT & TI
Electronic Displays
Horizontal Timing
79
ET/IT & TI
Electronic Displays
AM LCD - Panel with Digital RGB - Input
EO Transfer Fct.
Column Driver Bank
Gamma Corr.
Driver 1
Driver 2
Driver 3
Row
R
Digital
input
signals
G
Driver
1
Timing
Controller
B
Driver
Driver
2
Bank
Sync
Controls
Power Supply
LCD Module
Vcom
Inverter
Sync
Details of LCD module see ‚LCDs‘
80
ET/IT & TI
Electronic Displays
Power Sequencing
Power ON
Operating
Power OFF
Improper power
sequencing will
damage display !
81
ET/IT & TI
Electronic Displays
Embedded Systems
µC -, µP bus
• Graphics features
- Lower resolution as PCs
- Typically digital output
- Less standardized as PCs
- FPGA IP cores
- New: UGM-I/F
• ’To Do’
FPD output
Graphics Controller
- Interfacing µC or µP to Graphics Controller
µC ↔ GC
- Interfacing Graphics Controller to display
GC ↔ D
- Program Graphics IC and/or Operating System
SW / OS
82
ET/IT & TI
Electronic Displays
Interfacing Embedded Processors to Display Controllers
µC ↔ DC
µC ↔ GC
µC-specific
configuration
Complex !
83
ET/IT & TI
Electronic Displays
Resolution ↔ Pixel Rate
GC ↔ D
Resolution /106 Pixel
10
UXGA
SXGA
XGA
VGA
FPD @ 60 Hz
CRT @ 85 Hz
1
0.1
QVGA
0.01
0
100
200
300
400
Pixel Frequency /MHz
Pixel frequency = Resolution x Frame frequency
Data rate
(limit for parallel interfacing)
= Pixel frequency x RGB x Colour depth (limit for serial interfacing)
84
ET/IT & TI
Electronic Displays
Digital (TTL) Interfacing
GC ↔ D
• Signals :
- CK
: Pixel clock
- Hsync : Line clock
- Vsync : Frame clock
3 x 6 = 18 bpp
- Data : 12 - 24 bpp
• Many lines (length < 0.5 m)
→ Differential signalling input
• Panel specific timing required
Not standardized !
→ Programmable TCON
• High frequencies → EMI
→ Differential intra panel signalling
85
ET/IT & TI
Electronic Displays
Digital Input Timing Diagram
Example for XGA
16.7 ms
≈
Vsync
≈
Data
enable
Vporch
21.5 µs
≈
Hporch
Hsync
invalid
1
2
3
≈≈
Data
GC ↔ D
768
(XGA: 768 rows)
# of data per line : 1024 x RGB x bpp
Clocks and other controls omitted
86
ET/IT & TI
Electronic Displays
Adaptor Interface Board for 3.5” AMLCD
Standard
connector
to
customer
board incl.
single
voltage
supply
Power supply for
LCD module
Power
sequencing
ET/IT & TI
87
Electronic Displays
Block Diagram of 3.5” AMLCD
88
ET/IT & TI
Electronic Displays
Adaptation of LCD to Embedded System
Pin of panel
Pin of graphics controller
89
ET/IT & TI
Electronic Displays
Interface Timing of 3.5” AMLCD
GC ↔ D
Portrait orientation
There is practically no timing standard !
Individual adaptation needed
90
ET/IT & TI
Electronic Displays
ET/IT & TI
91
Electronic Displays
92
ET/IT & TI
Electronic Displays
Digital RGB vs. LVDS
GC ↔ D
• Digital RGB
• LVDS (see below)
93
ET/IT & TI
Electronic Displays
Display Color vs. Input Signal
R Data
GC ↔ D
G Data
R Data
8-bit
94
ET/IT & TI
Electronic Displays
Display Pixel Co - ordinates
Row (line) , column (data)
GC ↔ D
Example for XGA
1,1 1,2
1,1024
2,1 2,2
2,1024
768,1
768,1024
95
ET/IT & TI
Electronic Displays
Interfacing Data to Display Timing Controller
(clocks omitted)
GC ↔ D
LCD Type
GC
Output
96
ET/IT & TI
Electronic Displays
SW / OS
Programming of Graphics Controller
ANSI-C Library
C - Code
// SED 1374 - SHARP CQVGA STN 4bpp
...
// Draw 100x100 rectangle starting (0,0), color : red
for (y = 0; y < 100; y++)
{
pMem = (LPBYTE)MEM_OFFSET
+ (y * 320 * BitsPerPixel / 8) + 0;
for (x = 0; x < 100; x+=2)
{
pMem++; // draws 2 pixel
}
}
...
Each pixel of a character and for
graphics must be set individually
→ Use subroutines, libraries or operating system (OS)
97
ET/IT & TI
Electronic Displays
Adaptation of Embedded OS (here WIN CE) (I)
SW / OS
Use of standard types
reduce risk but only
certain panels defined !
Here: LQ104V1LG61
98
ET/IT & TI
Electronic Displays
Adaptation of Embedded OS (here WIN CE) (II)
SW / OS
If not predefined !
Examples
Beginning-of-line-wait:
Values from
panel spec !
Specifies the number of
pixel clock periods to add
to the beginning of a line
transmission before the
first set of pixels is sent
to the display.
End-of-frame line
clock wait count:
Specifies the number of
line clock periods to add
to the end of each frame.
ET/IT & TI
99
Electronic Displays
Integration of TCON into FPGA
Enables LCD module with only gate and source drivers
100
ET/IT & TI
Electronic Displays
Analogue input + 32-bit µC + TCON
101
ET/IT & TI
Electronic Displays
Customizable Display Controller IP-Core for Embedded Systems
Thesis by C. Bayer
µP
MicroProcessor
(µP)
Interface
IP
DisplayController
Display
Interface
Display
Memorycontroller
102
ET/IT & TI
Electronic Displays
µP Interface
Data
Display
Instruction
Control Block
ASCII
Data
Display Timing
Graphic Data
Page
Generator
Logic
Character Data
Text
Character Generator
Memory Controller Interface
Text Page
Character Memory
ET/IT & TI
Graphics
Graphic Page
103
Electronic Displays
Logic
Display
Timing Interface
104
ET/IT & TI
Electronic Displays
Display Controller for High End Embedded Applications
Typical features
• Graphics functions (2D, 3D): Point, line, triangle, polygon, BLT and pattern
• Output of analog RGB and digital RGB signals
• Up to 1024 x 768, 8 Bit/Pixel
- FUJITSU CORAL …
- TOSHIBA CAPRICORN
• Overlaying of layers
• Video input
ET/IT & TI
105
Electronic Displays
Display Controller Layer Technology
... for simplified implementation of various data including video input
106
ET/IT & TI
Electronic Displays
Graphics Display Controller (FUJITSU)
• High pin count because no standards for serial IF exits yet (APIX on the run)
ET/IT & TI
107
Electronic Displays
Graphics Display Controller with µC (TOSHIBA)
108
ET/IT & TI
Electronic Displays
Automotive Multimedia System
ET/IT & TI
109
Electronic Displays
Single Twisted Pair Automotive Pixel Link (APIX)
• ‘Cheap’ line from head unit
to display @ high data rate
• Separation of display and
controller saves cost
• APIX by INOVA, Munich
• Thesis e.g. by D. Lebherz
110
ET/IT & TI
Electronic Displays
Automotive Pixel Link (APIX by INOVA)
ET/IT & TI
111
Electronic Displays
Advanced Mobile Phone Colour LCD Graphics Controller
• One chip solution with gate
(row, scan) and source
(column, data) drivers
• Resolution : 176 x RGB x 220
• Up to 3 x 6 Bit colour
• Build-in RAM
• Power save mode:
partial display, 8 colour
• Multiple µC interface
112
ET/IT & TI
Electronic Displays
Serial Interfacing : LVDS, TMDS & GVIF
• Reduction of lines by using twisted pair (serial data)
• Small and thin cable (a must for laptops)
• ‘L’ and ‘H’ are defined as voltage difference instead of voltage level
→ low sensitivity to EMI
• LVDS is also used for digital image processing cameras
• Avoid static voltage generation by large numbers of ’L' or ’H' → Bit inversion
ET/IT & TI
113
Electronic Displays
Low Voltage Differential Signalling (RS-644)
Transition Minimised Differential Signalling
• Multiplexing of 7 signals (7 Bit) on 1 line
• Both use voltage difference (~ 0.1 V)
• TMDS has current loop (disadvantage for EMI)
• LVDS by NATIONAL SEMICONDUCTOR and TEXAS INSTRUMENTS
mainly used in laptops and for digital image processing
• TMDS by SILICON IMAGE, also named as PANEL-LINK and
Digital Video Interface (DVI)
114
ET/IT & TI
Electronic Displays
Digital Low Voltage Differential Signaling
GC ↔ D
Standard for VGA+ panels, differential signaling like USB, Ethernet, …
- PC standard: Digital Visual Interface
- TV standard: High Definition Multimedia Interface (DVI with DRM)
ET/IT & TI
115
Electronic Displays
Block Diagram LVDS & TMDS
LVDS : 4 data pairs
TMDS : 3 data pairs
116
ET/IT & TI
Electronic Displays
Bandwidth of PANEL-Link (TMDS)
MOST
GTF (VESA) :
Generalised
Timing
Formula
117
ET/IT & TI
TMDS Connectors
Electronic Displays
Digital Video Interface
Only digital
Digital & analog
Digital Flat Panel
118
ET/IT & TI
Electronic Displays
Serializer Deserializer Interface
• TTL (graphics IC out) serial TTL (display panel in)
• Single twisted pair for differential signalling
• Up to XGA support (65 MHz clock = 1.56 Gbit/sec)
• Some implementations with USB, audio, …
24 : 1 IF
ET/IT & TI
119
Electronic Displays
Serializer Deserializer Interface
• Cable have to be adapted for Bit-Error-Rate free transmission
640 Mbps
No Pre-Emphasis
100% Pre-Emphasis
120
ET/IT & TI
Electronic Displays
Gigabit Video Interface
• Single twisted pair for differential signalling
• Up to XGA support (65 MHz clock = 1.56 Gbit/sec)
Inventor : SONY
• 2nd link possible for higher speeds and resolutions
• No separate clock channel (skew is irrelevant)
ET/IT & TI
121
Electronic Displays
Questions
• Why are Hi Res panels so difficult to integrate into µC systems ?
• LVDS is used for Embedded System panels, DVI for PC-Systems
New trend: DISPLAYPORT – search web for benefits and issues
• What are the benefits of high end display controllers ?
• What are the benefits and limits of single twisted pair interfaces?
122

Display

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