LCDPresentation View Online - Revision history

TimM at 23:38, 1 January 2006

2006-01-01T23:38:27Z

← Older revision		Revision as of 23:38, 1 January 2006
Line 186:		Line 186:
	F 0 = 5x7 dots 1 = 5x10 dots		F 0 = 5x7 dots 1 = 5x10 dots
	A Address LCD Commands		A Address LCD Commands
	<pre>		</pre>

TimM at 23:37, 1 January 2006

2006-01-01T23:37:57Z

← Older revision		Revision as of 23:37, 1 January 2006
Line 157:		Line 157:
	</pre>		</pre>

	Parallel port signals So how do we connect to the parallel port? Data is easy just connect the parallel port data to LCD data. The LCD requires 2 or 3 control lines, the parallel port has 4 available; so there are several possibilities. We will use the connection used by Winamp.		<H3>Parallel port signals</H3>
			So how do we connect to the parallel port? Data is easy just connect the parallel port data to LCD data. The LCD requires 2 or 3 control lines, the parallel port has 4 available; so there are several possibilities. We will use the connection used by Winamp.


	Parallel port connection D-Type Hardware Pin No Name Direction Register Inverted LCD Sig LCD pin 1 -Strobe Out Control Yes E 6 2 Data 0 Out Data Data0 7 3 Data 1 Out Data Data1 8 4 Data 2 Out Data Data2 9 5 Data 3 Out Data Data3 10 6 Data 4 Out Data Data4 11 7 Data 5 Out Data Data5 12 8 Data 6 Out Data Data6 13 9 Data 7 Out Data Data7 14 14 -Linefeed Out Control Yes R/-W 5 16 Initialize Out Control RS 4 18 25 Ground Gnd Gnd 2		<H3>Parallel port connection</H3>
			D-Type Hardware Pin No Name Direction Register Inverted LCD Sig LCD pin 1 -Strobe Out Control Yes E 6 2 Data 0 Out Data Data0 7 3 Data 1 Out Data Data1 8 4 Data 2 Out Data Data2 9 5 Data 3 Out Data Data3 10 6 Data 4 Out Data Data4 11 7 Data 5 Out Data Data5 12 8 Data 6 Out Data Data6 13 9 Data 7 Out Data Data7 14 14 -Linefeed Out Control Yes R/-W 5 16 Initialize Out Control RS 4 18 25 Ground Gnd Gnd 2

			<H3>LCD Commands</H3>
			<pre>
			D7 D6 D5 D4 D3 D2 D1 D0 Instruction/Description
			0 0 0 0 0 0 0 1 Clear Display
			0 0 0 0 0 0 1 * Return to Home Position
			0 0 0 0 0 1 ID S Set Cursor Move Direction
			0 0 0 0 1 D C B Enable Display/Cursor
			0 0 0 1 SC RL * * Cursor/Display Shift
			0 0 1 DL N F * * Set Interface Length
			0 1 A A A A A A Set CGRAM Address
			1 A A A A A A A Set Display Address
			ID 0 = Decrement cursor position 1 = Increment cursor position
			S 0 = No display shift 1 = Display shift
			D 0 = Display off 1 = Display on
			C 0 = Cursor off 1 = Cursor on
			B 0 = Cursor blink off 1 = Cursor blink on
			SC 0 = Move cursor 1 = Shift display
			RL 0 = Shift left 1 = Shift right
			DL 0 = 4-bit interface 1 = 8-bit interface
			N 0 = 1/8 or 1/11 Duty (1 line) 1 = 1/16 Duty (2 lines)
			F 0 = 5x7 dots 1 = 5x10 dots
			A Address LCD Commands
			<pre>

	D7 D6 D5 D4 D3 D2 D1 D0 Instruction/Description 0 0 0 0 0 0 0 1 Clear Display 0 0 0 0 0 0 1 * Return to Home Position 0 0 0 0 0 1 ID S Set Cursor Move Direction 0 0 0 0 1 D C B Enable Display/Cursor 0 0 0 1 SC RL * * Cursor/Display Shift 0 0 1 DL N F * * Set Interface Length 0 1 A A A A A A Set CGRAM Address 1 A A A A A A A Set Display Address ID 0 = Decrement cursor position 1 = Increment cursor position S 0 = No display shift 1 = Display shift D 0 = Display off 1 = Display on C 0 = Cursor off 1 = Cursor on B 0 = Cursor blink off 1 = Cursor blink on SC 0 = Move cursor 1 = Shift display RL 0 = Shift left 1 = Shift right DL 0 = 4-bit interface 1 = 8-bit interface N 0 = 1/8 or 1/11 Duty (1 line) 1 = 1/16 Duty (2 lines) F 0 = 5x7 dots 1 = 5x10 dots A Address LCD Commands

			<H3>LCD Commands</H3>
			RS is register select 0=command, 1=data. R/-W is read/write control 0=write,1=read. Commands are issued with R/S=0 and R/-W=0. Put the command on the data lines, and toggle E from L->H->L.

	LCD Commands RS is register select 0=command, 1=data. R/-W is read/write control 0=write,1=read. Commands are issued with R/S=0 and R/-W=0. Put the command on the data lines, and toggle E from L->H->L. The Clear Display and Return Home commands can take up to 1.64ms, the rest take ~40usec. Even with only 8 commands, it can be a bit confusing with all the options We only need a subset of the commands to initialize the LCD. 1. Set Interface Length - use 0011 1000 8 bit interface, 2 lines, 5x7 dot characters 2. Enable Display/Cursor - use 0000 1100 display on, no cursor 3. Clear Display - use 0000 0001 no options 4. Set Cursor Move Direction - use 0000 0110 increment cursor, no shift Then we can use Set Display Address and data writes to put characters on the display.		The Clear Display and Return Home commands can take up to 1.64ms, the rest take ~40usec.

			Even with only 8 commands, it can be a bit confusing with all the options We only need a subset of the commands to initialize the LCD.

	~~14 Writing Data After initializing per the previous slide writing starts at the first position on line~~ 1. ~~To write data, we set RS=1, R/~~-W=0, put the ASCII character on the data lines, and toggle E from L->H->L. The controller has 80 bytes of data memory that are organized differently depending on the mode. In single line mode it starts at 0 offset and is linearly addressed to offset 0x4F. In some documents, you will see memory addressed as 0x80 0xCF; this is the actual command to set the memory address (remember command bit 0x80 indicates display address set). In 2 line mode the display memory is split with the first 40 bytes starting at offset 0 (0x80) and the second line at offset 0x40 (0xC0). 15 Display Addressing The base controller can display 2 lines x 8 char. For each additional 8 characters, ~~a display driver is added to handle another~~ 2 lines ~~x 8. For a 1 line x 16 characters~~, there are two possibilities. There could be the controller and a display driver, in which case it would look like a single line display. The other case is to use only the controller and treat it as a 2 line x 8 character display with the 2 lines on one line. This makes a difference in how you address the second 8 characters! Four line displays, for example 4 lines x 20 characters, the other lines are mapped onto lines 1 and 2. Line 3 is the second half of line 1 and line 4 is the second half of line 2. Line 1 0x80 0x93 Line 2 0xC0 0xD3 Line 3 0x94 0xA7 Line 4 0xD4 - 0xE7 So what about the code? There are several ways to talk to the parallel port 1. Direct port I/O requires root authority 2. Write a kernel device driver complex (although Mark Harris has done most of the leg work for us) and non standard 3. Use the existing parallel port device driver for device /dev/parport0 This can run in user state and it is commonly available. I used this option. File device drivers support open, close, read, and write for normal operation. Unfortunately toggling control port bits is not normal operation . For hardware specific operations, the ioctl (i/o control) operation is provided. We will use this for both data and control writes. The constants are in include/linux/ppdev.h		1. Set Interface Length - use 0011 1000 8 bit interface, 2 lines, 5x7 dot characters

			2. Enable Display/Cursor - use 0000 1100 display on, no cursor

			3. Clear Display - use 0000 0001 no options 4. Set Cursor Move Direction - use 0000 0110 increment cursor, no shift Then we can use Set Display Address and data writes to put characters on the display.


			<H3>Writing Data</H3>
			After initializing per the previous slide writing starts at the first position on line 1. To write data, we set RS=1, R/-W=0, put the ASCII character on the data lines, and toggle E from L->H->L. The controller has 80 bytes of data memory that are organized differently depending on the mode. In single line mode it starts at 0 offset and is linearly addressed to offset 0x4F. In some documents, you will see memory addressed as 0x80 0xCF; this is the actual command to set the memory address (remember command bit 0x80 indicates display address set). In 2 line mode the display memory is split with the first 40 bytes starting at offset 0 (0x80) and the second line at offset 0x40 (0xC0).

			<H3>Display Addressing</H3>
			The base controller can display 2 lines x 8 char. For each additional 8 characters, a display driver is added to handle another 2 lines x 8. For a 1 line x 16 characters, there are two possibilities. There could be the controller and a display driver, in which case it would look like a single line display. The other case is to use only the controller and treat it as a 2 line x 8 character display with the 2 lines on one line. This makes a difference in how you address the second 8 characters!

			Four line displays, for example 4 lines x 20 characters, the other lines are mapped onto lines 1 and 2. Line 3 is the second half of line 1 and line 4 is the second half of line 2.

			Line 1 0x80 0x93

			Line 2 0xC0 0xD3

			Line 3 0x94 0xA7

			Line 4 0xD4 - 0xE7


			<H3>So what about the code?</H3> There are several ways to talk to the parallel port
			1. Direct port I/O requires root authority
			2. Write a kernel device driver complex (although Mark Harris has done most of the leg work for us) and non standard
			3. Use the existing parallel port device driver for device /dev/parport0 This can run in user state and it is commonly available. I used this option. File device drivers support open, close, read, and write for normal operation. Unfortunately toggling control port bits is not normal operation . For hardware specific operations, the ioctl (i/o control) operation is provided. We will use this for both data and control writes. The constants are in include/linux/ppdev.h





			<H3>Control Functions</H3>
	When attaching an LCD display, there are several options for the control functions.		When attaching an LCD display, there are several options for the control functions.
	Rather than invent our own, we used an existing definition originally used by a Winamp		Rather than invent our own, we used an existing definition originally used by a Winamp
Line 228:		Line 279:
	LCD has back light capability, the connections may not be on the connector		LCD has back light capability, the connections may not be on the connector

	== [[http://k-lug.org/old.site/presentations/lcd/lcd_project.tar.gz Download the Tarball containing source code here]] ==		== [[http://k-lug.org/old.site/presentations/lcd/lcd_project.tar.gz Download the Tarball containing source code here]] ==</pre>

TimM at 23:30, 1 January 2006

2006-01-01T23:30:48Z

@@ Line 99: / Line 99: @@
 <H3>Write timing    LCD controller </H3>
 <pre>
-WRITE: ______ _____________________________ ___________ RS ______X_________valid_RS_level______X__________ | | | | |<--40ns->| 10ns->| |<-- ______| | | |____________ R/W ______\_________|___R/W_low____|____/_____________ | | |<----230ns--->| | | |<-------------|------500ns------>| |______________| |_________ E ________________/ \__________________/ 20ns(max)-->||<-- -->||<--20ns(max) |<--80ns-->|| | -->| |<--10ns __________________|_______________|________________ D0-D7 __________________X__valid_data___X____________ Write timing - Port I/O _______ _____________ ____________________ __ RS_______X_____________X____________________X__ ____ __ __ R/-W ____\____________/ \___________________/ Note that for  write and wait  R/-W can be tied low ______ ________ __ __ _______ _______ __ DATA ______X________X__ __X_______X_______X__ Bits 7-0 7-4 3-0 ___ ___ ___ E ________/ \____________/ \__/ \___ 8 Bit 4 Bit
+WRITE:
 </pre>

TimM at 23:25, 1 January 2006

2006-01-01T23:25:44Z

← Older revision		Revision as of 23:25, 1 January 2006
Line 89:		Line 89:


	<H3>Interface - Timing Control Signal Timing If you look at the spec sheet you will find diagrams like the next page. These are important if you are running at the maximum speed the display can support, such as memory mapped I/O with a micro-processor. For a parallel port or port based I/O on a micro-processor it is simpler (slower) we usually won't come close to these limits. In compatibility mode, the parallel port is simulating talking to a printer over an 8MHz AT bus. The minimum transition is about 500ns even on a GHz machine.		<H3>Interface - Timing </H3>
			Control Signal Timing

			If you look at the spec sheet you will find diagrams like the next page. These are important if you are running at the maximum speed the display can support, such as memory mapped I/O with a micro-processor.

	~~8 Write timing LCD controller WRITE: ______ _____________________________ ___________ RS ______X_________valid_RS_level______X__________ \| \| \| \| \|<--40ns->\| 10ns->\| \|<-- ______\| \| \| \|____________ R~~/~~W ______\_________\|___R/W_low____\|____/_____________ \| \| \|<----230ns--->\| \| \| \|<-------------\|------500ns----~~-~~->\| \|______________\| \|_________ E ________________/ \__________________/ 20ns~~(~~max~~)-->\|\|<-- -->\|\|<--20ns(max) \|<--80ns-->\|\| \| -->\| \|<--10ns __________________\|_______________\|________________ D0-D7 __________________X__valid_data___X____________ Write timing - Port I/O _______ _____________ ____________________ __ RS_______X_____________X____________________X__ ____ __ __ R/-W ____\____________/ \___________________/ Note that for write and wait R/-W can be tied low ______ ________ __ __ _______ _______ __ DATA ______X________X__ __X_______X_______X__ Bits 7-0 7-4 3-0 ___ ___ ___ E ________/ \____________/ \__/ \___ 8 Bit 4 Bit		For a parallel port or port based I/O on a micro-processor it is simpler (slower) we usually won't come close to these limits. In compatibility mode, the parallel port is simulating talking to a printer over an 8MHz AT bus. The minimum transition is about 500ns even on a GHz machine.


			<H3>Write timing LCD controller </H3>
			<pre>
			WRITE: ______ _____________________________ ___________ RS ______X_________valid_RS_level______X__________ \| \| \| \| \|<--40ns->\| 10ns->\| \|<-- ______\| \| \| \|____________ R/W ______\_________\|___R/W_low____\|____/_____________ \| \| \|<----230ns--->\| \| \| \|<-------------\|------500ns------>\| \|______________\| \|_________ E ________________/ \__________________/ 20ns(max)-->\|\|<-- -->\|\|<--20ns(max) \|<--80ns-->\|\| \| -->\| \|<--10ns __________________\|_______________\|________________ D0-D7 __________________X__valid_data___X____________ Write timing - Port I/O _______ _____________ ____________________ __ RS_______X_____________X____________________X__ ____ __ __ R/-W ____\____________/ \___________________/ Note that for write and wait R/-W can be tied low ______ ________ __ __ _______ _______ __ DATA ______X________X__ __X_______X_______X__ Bits 7-0 7-4 3-0 ___ ___ ___ E ________/ \____________/ \__/ \___ 8 Bit 4 Bit
			</pre>

	Parallel port signals So how do we connect to the parallel port? Data is easy just connect the parallel port data to LCD data. The LCD requires 2 or 3 control lines, the parallel port has 4 available; so there are several possibilities. We will use the connection used by Winamp.		Parallel port signals So how do we connect to the parallel port? Data is easy just connect the parallel port data to LCD data. The LCD requires 2 or 3 control lines, the parallel port has 4 available; so there are several possibilities. We will use the connection used by Winamp.

TimM at 23:23, 1 January 2006

2006-01-01T23:23:01Z

← Older revision		Revision as of 23:23, 1 January 2006
Line 48:		Line 48:

	<H3>Interface - Mechanical </H3>		<H3>Interface - Mechanical </H3>
	There are several different styles of interface layouts For a given layout the pins will have the same function The same pin numbers will have the same function across layouts ~~16 pin inline 14 pin dual~~		There are several different styles of interface layouts For a given layout the pins will have the same function The same pin numbers will have the same function across layouts.


	<H3>Interface - Electrical</H3>		<H3>Interface - Electrical</H3>
	Pin# Pin# Symbol Level Function 8 bit 4 bit ==== ====== ===== ====== ========================== 1 1 Vss GND Ground 2 2 Vcc +5V Module power 3 3 Vee NOTE1 Liquid crystal drive 4 4 RS H/L Register select, H=data, L=command 5 5 R/~W H/L Read/Write, H=read , L=write 6 6 E H->L Edge-sensitive Enable 7 - DB0 Data bit 0 (not used in 4 bit mode) 8 - DB1 Data bit 1 (not used in 4 bit mode) 9 - DB2 Data bit 2 (not used in 4 bit mode) 10 - DB3 Data bit 3 (not used in 4 bit mode) 11 7 DB4 Data bit 4 12 8 DB5 Data bit 5 13 9 DB6 Data bit 6 14 10 DB7 Data bit 7 NOTE1: On standard modules Vee is between GND and 5V; on temperature extended modules it is between GND and -7V		<pre>
			Pin# Pin# Symbol Level Function
			8 bit 4 bit
			==== ====== ===== ====== ==========================
			1 1 Vss GND Ground
			2 2 Vcc +5V Module power
			3 3 Vee NOTE1 Liquid crystal drive
			4 4 RS H/L Register select, H=data, L=command
			5 5 R/~W H/L Read/Write, H=read , L=write
			6 6 E H->L Edge-sensitive Enable
			7 - DB0 Data bit 0 (not used in 4 bit mode)
			8 - DB1 Data bit 1 (not used in 4 bit mode)
			9 - DB2 Data bit 2 (not used in 4 bit mode)
			10 - DB3 Data bit 3 (not used in 4 bit mode)
			11 7 DB4 Data bit 4
			12 8 DB5 Data bit 5
			13 9 DB6 Data bit 6
			14 10 DB7 Data bit 7
			</pre>
			NOTE1: On standard modules Vee is between GND and 5V; on temperature extended modules it is between GND and -7V



	<H3>Interface - Electrical</H3>		<H3>Interface - Electrical</H3>
	Back Lighting Power may be additional interface pins or separate connections LED simple, high power Electro-Luminescent complex drive circuit, less power Cold Cathode Fluorescent complex drive circuit, less power, not usually found on char displays		Back Lighting
			Power may be additional interface pins or separate connections
			LED simple, high power Electro-Luminescent complex drive circuit, less power Cold Cathode Fluorescent complex drive circuit, less power, not usually found on char displays

TimM at 23:18, 1 January 2006

2006-01-01T23:18:59Z

← Older revision		Revision as of 23:18, 1 January 2006
Line 45:		Line 45:
	messy and discouraging. This kit is designed to make the interface simple. It was		messy and discouraging. This kit is designed to make the interface simple. It was
	designed by [[Dennis DeLorme]] and [[mailto:neff@acm.org Kevin Neff]] – if you have questions they should be able to help.		designed by [[Dennis DeLorme]] and [[mailto:neff@acm.org Kevin Neff]] – if you have questions they should be able to help.


			<H3>Interface - Mechanical </H3>
			There are several different styles of interface layouts For a given layout the pins will have the same function The same pin numbers will have the same function across layouts 16 pin inline 14 pin dual


			<H3>Interface - Electrical</H3>
			Pin# Pin# Symbol Level Function 8 bit 4 bit ==== ====== ===== ====== ========================== 1 1 Vss GND Ground 2 2 Vcc +5V Module power 3 3 Vee NOTE1 Liquid crystal drive 4 4 RS H/L Register select, H=data, L=command 5 5 R/~W H/L Read/Write, H=read , L=write 6 6 E H->L Edge-sensitive Enable 7 - DB0 Data bit 0 (not used in 4 bit mode) 8 - DB1 Data bit 1 (not used in 4 bit mode) 9 - DB2 Data bit 2 (not used in 4 bit mode) 10 - DB3 Data bit 3 (not used in 4 bit mode) 11 7 DB4 Data bit 4 12 8 DB5 Data bit 5 13 9 DB6 Data bit 6 14 10 DB7 Data bit 7 NOTE1: On standard modules Vee is between GND and 5V; on temperature extended modules it is between GND and -7V



			<H3>Interface - Electrical</H3>
			Back Lighting Power may be additional interface pins or separate connections LED simple, high power Electro-Luminescent complex drive circuit, less power Cold Cathode Fluorescent complex drive circuit, less power, not usually found on char displays






			<H3>Interface - Options </H3>
			Hardware Software 8 bit Write and wait - more interface lines - Write data and wait for - faster max time 4 bit - Simple - 4 less interface lines Check busy - needs 2 write operations - Write and check status - May be faster - Requires bidirectional data bus


			<H3>Interface - Timing Control Signal Timing If you look at the spec sheet you will find diagrams like the next page. These are important if you are running at the maximum speed the display can support, such as memory mapped I/O with a micro-processor. For a parallel port or port based I/O on a micro-processor it is simpler (slower) we usually won't come close to these limits. In compatibility mode, the parallel port is simulating talking to a printer over an 8MHz AT bus. The minimum transition is about 500ns even on a GHz machine.


			8 Write timing LCD controller WRITE: ______ _____________________________ ___________ RS ______X_________valid_RS_level______X__________ \| \| \| \| \|<--40ns->\| 10ns->\| \|<-- ______\| \| \| \|____________ R/W ______\_________\|___R/W_low____\|____/_____________ \| \| \|<----230ns--->\| \| \| \|<-------------\|------500ns------>\| \|______________\| \|_________ E ________________/ \__________________/ 20ns(max)-->\|\|<-- -->\|\|<--20ns(max) \|<--80ns-->\|\| \| -->\| \|<--10ns __________________\|_______________\|________________ D0-D7 __________________X__valid_data___X____________ Write timing - Port I/O _______ _____________ ____________________ __ RS_______X_____________X____________________X__ ____ __ __ R/-W ____\____________/ \___________________/ Note that for write and wait R/-W can be tied low ______ ________ __ __ _______ _______ __ DATA ______X________X__ __X_______X_______X__ Bits 7-0 7-4 3-0 ___ ___ ___ E ________/ \____________/ \__/ \___ 8 Bit 4 Bit


			Parallel port signals So how do we connect to the parallel port? Data is easy just connect the parallel port data to LCD data. The LCD requires 2 or 3 control lines, the parallel port has 4 available; so there are several possibilities. We will use the connection used by Winamp.


			Parallel port connection D-Type Hardware Pin No Name Direction Register Inverted LCD Sig LCD pin 1 -Strobe Out Control Yes E 6 2 Data 0 Out Data Data0 7 3 Data 1 Out Data Data1 8 4 Data 2 Out Data Data2 9 5 Data 3 Out Data Data3 10 6 Data 4 Out Data Data4 11 7 Data 5 Out Data Data5 12 8 Data 6 Out Data Data6 13 9 Data 7 Out Data Data7 14 14 -Linefeed Out Control Yes R/-W 5 16 Initialize Out Control RS 4 18 25 Ground Gnd Gnd 2


			D7 D6 D5 D4 D3 D2 D1 D0 Instruction/Description 0 0 0 0 0 0 0 1 Clear Display 0 0 0 0 0 0 1 * Return to Home Position 0 0 0 0 0 1 ID S Set Cursor Move Direction 0 0 0 0 1 D C B Enable Display/Cursor 0 0 0 1 SC RL * * Cursor/Display Shift 0 0 1 DL N F * * Set Interface Length 0 1 A A A A A A Set CGRAM Address 1 A A A A A A A Set Display Address ID 0 = Decrement cursor position 1 = Increment cursor position S 0 = No display shift 1 = Display shift D 0 = Display off 1 = Display on C 0 = Cursor off 1 = Cursor on B 0 = Cursor blink off 1 = Cursor blink on SC 0 = Move cursor 1 = Shift display RL 0 = Shift left 1 = Shift right DL 0 = 4-bit interface 1 = 8-bit interface N 0 = 1/8 or 1/11 Duty (1 line) 1 = 1/16 Duty (2 lines) F 0 = 5x7 dots 1 = 5x10 dots A Address LCD Commands


			LCD Commands RS is register select 0=command, 1=data. R/-W is read/write control 0=write,1=read. Commands are issued with R/S=0 and R/-W=0. Put the command on the data lines, and toggle E from L->H->L. The Clear Display and Return Home commands can take up to 1.64ms, the rest take ~40usec. Even with only 8 commands, it can be a bit confusing with all the options We only need a subset of the commands to initialize the LCD. 1. Set Interface Length - use 0011 1000 8 bit interface, 2 lines, 5x7 dot characters 2. Enable Display/Cursor - use 0000 1100 display on, no cursor 3. Clear Display - use 0000 0001 no options 4. Set Cursor Move Direction - use 0000 0110 increment cursor, no shift Then we can use Set Display Address and data writes to put characters on the display.


			14 Writing Data After initializing per the previous slide writing starts at the first position on line 1. To write data, we set RS=1, R/-W=0, put the ASCII character on the data lines, and toggle E from L->H->L. The controller has 80 bytes of data memory that are organized differently depending on the mode. In single line mode it starts at 0 offset and is linearly addressed to offset 0x4F. In some documents, you will see memory addressed as 0x80 0xCF; this is the actual command to set the memory address (remember command bit 0x80 indicates display address set). In 2 line mode the display memory is split with the first 40 bytes starting at offset 0 (0x80) and the second line at offset 0x40 (0xC0). 15 Display Addressing The base controller can display 2 lines x 8 char. For each additional 8 characters, a display driver is added to handle another 2 lines x 8. For a 1 line x 16 characters, there are two possibilities. There could be the controller and a display driver, in which case it would look like a single line display. The other case is to use only the controller and treat it as a 2 line x 8 character display with the 2 lines on one line. This makes a difference in how you address the second 8 characters! Four line displays, for example 4 lines x 20 characters, the other lines are mapped onto lines 1 and 2. Line 3 is the second half of line 1 and line 4 is the second half of line 2. Line 1 0x80 0x93 Line 2 0xC0 0xD3 Line 3 0x94 0xA7 Line 4 0xD4 - 0xE7 So what about the code? There are several ways to talk to the parallel port 1. Direct port I/O requires root authority 2. Write a kernel device driver complex (although Mark Harris has done most of the leg work for us) and non standard 3. Use the existing parallel port device driver for device /dev/parport0 This can run in user state and it is commonly available. I used this option. File device drivers support open, close, read, and write for normal operation. Unfortunately toggling control port bits is not normal operation . For hardware specific operations, the ioctl (i/o control) operation is provided. We will use this for both data and control writes. The constants are in include/linux/ppdev.h

TimM at 23:11, 1 January 2006

2006-01-01T23:11:24Z

← Older revision		Revision as of 23:11, 1 January 2006
Line 12:		Line 12:

	<h3>LCD Kit Parts list</h3>		<h3>LCD Kit Parts list</h3>
			<pre>
	__ 10K trim pot		__ 10K trim pot
	__ 25 pin male D IDC		__ 25 pin male D IDC
Line 24:		Line 25:
	__ 2 line x 12 character LCD		__ 2 line x 12 character LCD
	__ Interface Circuit board		__ Interface Circuit board
			</pre>

	<h3>Kit Options</h3>		<h3>Kit Options</h3>

TimM at 23:09, 1 January 2006

2006-01-01T23:09:47Z

← Older revision		Revision as of 23:09, 1 January 2006
Line 44:		Line 44:
	messy and discouraging. This kit is designed to make the interface simple. It was		messy and discouraging. This kit is designed to make the interface simple. It was
	designed by [[Dennis DeLorme]] and [[mailto:neff@acm.org Kevin Neff]] – if you have questions they should be able to help.		designed by [[Dennis DeLorme]] and [[mailto:neff@acm.org Kevin Neff]] – if you have questions they should be able to help.







	When attaching an LCD display, there are several options for the control functions.		When attaching an LCD display, there are several options for the control functions.

TimM: /* Intro to the LCD Kit Project */

2006-01-01T23:01:53Z

Intro to the LCD Kit Project

@@ Line 8: / Line 8: @@
 [http://www.pcig.info/uploads/Main/LCDTux.jpg http://www.pcig.info/uploads/Main/LCDTuxsm.jpg]
-== Intro to the LCD Kit Project ==
+<H2> Intro to the LCD Kit Project </H2>
 Welcome to the first K-LUG project involving the attaching of interesting hardware to a computer.  We created this project because one member had several monitorless servers he wanted to view performance stats on.  We also picked this project so we would have some interesting code to write, and we figured it would be cheap, easy and fun!  Ideally our attached display would connect via USB, however, we chose a parallel port connected display because no one seems to use the parallel port anymore, and by using a parallel port the kit was easier to code and cheaper to buy.
 When you first look at attaching an LCD display to the parallel port, it looks simple – a bunch of
@@ Line 61: / Line 90: @@
 | --|| || (16) || (back light -)
 |}
 == [[http://k-lug.org/old.site/presentations/lcd/lcd_project.tar.gz Download the Tarball containing source code here]] ==

TimM: /* Intro to the LCD Kit Project */

2006-01-01T22:53:42Z

Intro to the LCD Kit Project

@@ Line 20: / Line 20: @@
 add-on. The connections are as follows....
 will convert more later...
 {| border="1" cellpadding="2" align="center"
-|+Multiplication table
+|+ LCD Connections table
 |-
 ! Parallel Port !! Port Function !! LCD !! LCD Function
@@ Line 28: / Line 31: @@
 |18-25||GND||1||GND
 |-
-| || || 2 ||+5V
+| -- || || 2 ||+5V
 |-
-! 2
+|5 || Data 3 || 10 || DB 3
 |-
-! 3
+|6 || Data 4 || 11 || DB 4
 |-
-! 4
+|7 || Data 5 || 12 || DB 5
 |-
-! 5
+|8 || Data 6 || 13 || DB 6
-| 5 || 10 || 15
+|-
 |}
 == [[http://k-lug.org/old.site/presentations/lcd/lcd_project.tar.gz Download the Tarball containing source code here]] ==