LCD Serial Backpack® and 2x16 Serial LCDs
Contents
1. User s Manual BPK XXX v6 0 03 98 pg 1 LCD Serial Backpack and 2x16 Serial LCDs TheLCD Serial Backpack is a daughterboard that attaches to standard character LCD modules It receives data serially and displays it on the LCD The Backpack supports any alphanumeric LCD up to 80 screen characters e g 4 lines by 20 characters It accepts serial data at 2400 or 9600 baud switch selectable It is sold by itself or preinstalled to high quality 2x16 LCD modules The Backpack has two modes text and instruction It defaults to text mode any data sent to the Backpack is displayed on the screen Send the string HELLO and HELLO appears on the LCD To distinguish text from instructions eg clear screen position cursor etc the Backpack looks for an instruction prefix ASCII 254 The byte following prefix is treated as an instruction After the instruction code the Backpack returns to text mode Table of Contents Description and Installation to Typical LCDS eeeeceeeeeeeeneeeeeeeeeeeeeeeeeeeeeeeeseeseeeeeneeseeeeneees 2 Quick Checkout and Contrast Adjustment ceecececeeeeeeeeeeeeneeeeeeeeeeteeeeeeeeteaeeseeeseaeesiaeeeaeeenneesas 2 Configuratio acin nanea aaa O R EAE A A aaa aa shag O EA A ENSE 3 Hookup TON US Eisrega a deen eee A 3 Basic Operati oiietn iina a aeoea e Ee e aE a ESEA seein 3 Positioning thie CUSO aaa E bd a E EEA E AA E ANAE ENEE 4 Defining Custom SYMDOlS sesiis ninaiona tisa aen2. RS 232 or inverted TTL CMOS 2400 or 9600 N81 Operating temperature Storage temperature eceeee LCD type BPK 216x series Optimum viewing direction eecceeceeeeeeeeeeeeeeeeeeeeeeeeneeteeeeneess H 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com
3. Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 6 Program Examples Any computer programming language that can produce serial output 2400 or 9600 bps N81 can talk tothe LCD Serial Backpack The examples here are in BASIC chosen because of its popularity and readability Don t be put off by the size of the programs they are mostly comments These examples are meant to illustrate only the fundamentals More elaborate examples are available from www seetron com Program BPKDEMO BAS This program demonstrates fundamental techniques of driving the LCD Serial Backpack R in BASIC compatible with QBASIC Quick BASIC First BASIC and Power BASIC First BASIC an excellent shareware compiler is available from www powerbasic com Start by defining some useful constants for the Backpack I 254 Instruction prefix value CLR 1 LCD clear screen instruction LINE1 128 Address of first character of lst line LINE2 192 Address of first character of 2nd line Open the serial port coml for output at 9600 baud Make sure Backpack is also set for 9600 Turn off all handshaking CD CS DS by Quickie Program setting to zero 0 OPEN COMI S600 NS pl CDUpCSs0 Ds0 FOR TOUIPUT AST Want fast results All you Once the port is open we can print to it Start by clearing the screen need are these two lines in case t
4. the cursor N serout 0 n9600 I L1_C7 DEC Wait 2 secs Clear the LCD screen Print the label Move to line 1 character 7 Print value of b2 followed by 2 spaces Increment b2 Slow the loop down Repeat endlessly 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 8 Dimensions and Backlight Hookup The drawing below gives the primary dimensions of the 2x16 LCDs sold with our BPK 216N and BPK 216L products Three LCD manufacturers are listed Truly Data Vision DV and Powertip PT since we have at times used LCDs from each of these companies Powertip is our primary supplier Truly DV PT A y offset pcb edge to hole ctr 2 50 2 50 2 50 B y pcb height 36 00 36 00 36 00 C y hole spacing 31 00 31 00 31 00 D y screen opening 13 80 16 10 16 20 L E y character size 4 35 4 89 5 94 F x character size 2 95 2 78 2 95 G x offset pcb edge to hole ctr 2 50 2 50 3 55 H xscreen frame 73 70 71 20 71 00 x screen opening 64 50 62 50 66 00 yO J x hole spacing 75 00 75 00 75 00 K x pcb width 80 00 80 00 80 00 i a L y frame height 24 80 26 20 25 00 Gak J a mounting hole diameter 2 50 2 50 2 50 be K gt frame depth non backlit 5 00 4 70 5 00 frame depth LED backlit 8 50 9 40 8 50 aa Ea LED Backlight A R of h Imensions in mm H AA
5. 8 eee To position the cursor send the instruction prefix byte ASCII 254 followed by the set position byte value For example to move to line 2 character 4 send lt 254 gt lt 196 gt Note lt gt means a byte set to the value See program examples 1x16 LCDs set LINES switch to 2 4 character aaa BaD position set position 428 129 130 ese 192 193 194 ee instruction four line LCDs set LINES switch to 2 4 0 1 2 3 4 5 6 eee line 1 128 129 130 131 132 133 134 line 2 192 193 194 195 196 197 198 line 3 148 149 150 151 152 153 154 eee line 4 212 213 214 215 216 217 218 eee Figure 4 Cursor positioning 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 5 Defining Custom Symbols Most of the LCD characters figure 6 cannot be changed because they are stored in ROM However the first eight symbols corresponding to ASCII 0 through 7 are stored in RAM By writing new values to the character generator CG RAM you can alter these characters Changing a symbol is easy just point to the beginning of the symbol s RAM location then write eight bytes whose bits form the desired pattern Then position the cursor onto the screen See figure 5 Manipulating custom characters allows you to create all kinds of special effects including s
6. CD clear screen instruction SYMBOL LINE2 192 Address of lst char of 2nd line SYMBOL L1_C7 135 Address of line 1 character 7 Now clear the screen in case there s text left from a previous run of the program Note that there s a 1 second PAUSE prior to sending any data to the Backpack This gives the Backpack plenty of time to initialize the LCD after power up pause 1000 serout 0 n2400 I CLR Clear the LCD screen serout 0 n2400 Hello World Print message Positioning the cursor requires sending the instruction prefix ASCII 254 assigned the symbol I followed by an address serout 0 n2400 I LINE2 line 2 Move to line 2 and print simulate a common application by printing a label on the updating some data by positioning the cursor Wait 2 secs Clear the LCD screen Print the label Now we ll screen and pause 2000 serout 0 n2400 I CLR t serout 0 n2400 Count Again serout 0 n2400 I L1_C7 serout 0 n2400 b2 Move to line 1 character 7 Print value of b2 followed by 2 spaces BASIC STAMP I Quickie Program Type and run just this line in PBASIC 1 and Hello World appears on the display b2 b2 1 pause 200 goto Again Increment b2 Slow the loop down Repeat endlessly LCD Serial Program BPKDEMS2 BS2 This program demonstrates fundamental techniques of driving the in BASIC from the BASIC Stamp II that the Backp
7. a rei ae delish 5 Program EXAMple Screener eian eria sega E AE Eia iaieiiea T Dimensio S ereere aana E EAEN aO N 8 Backlight HOOKUP nrerin pe ete ie ae eee 8 FREVISIOMAFISUONY si ensesine ae vada e E a de EA aeae e dhaeaesSeeh stendeaceaes 8 SPECIGI Si dasoa S E asseceensan 8 Disclaimer of Liability Scott Edwards Electronics Inc is not responsible for any special incidental or consequential damages resulting from any breach of warranty or under any legal theory including lost profits downtime goodwill damage to or replacement of equipment or property and any costs or recovering reprogramming or reproducing of data associated with the use of the hardware or software described herein Warranty Scott Edwards Electronics Inc warrants this product against defects in materials and workmanship for a period of 90 days If you discover a defect we will at our option repair replace or refund the purchase price Return the product with a description of the problem We will return your product or its replacement via standard shipping Expedited shipping is available at the customer s expense e Note Physically abusing the module or attempting to repair or modify it voids this warranty Trademarks and Copyrights LCD Serial Backpack is a registered trademark of Scott Edwards Electronics Inc BASIC Stamp is a registered trademark of Parallax Inc All trademarked names referenced herein are the property of their respective holde
8. ack is connected to I O pin PO of the Stamp and that it is set for 9600 bps Backpack R BASIC STAMP II It assumes Start by defining some useful constants for the Backpack Quickie Program N9600 con 4054 Baudmode for 9600 bps inverted I con 254 Instruction prefix value CLR con 1 LCD clear screen instruction LINE2 con 192 Address of 1st char of 2nd line L1_C7 con 135 Address of line 1 character 7 pause 1000 serout 0 n9600 I CLR pause 1 serout 0 n9600 Hello World Positioning the cursor requires sending the instruction prefix assigned the symbol serout 0 n9600 I LINE2 line 2 t 254 I Type and run just these lines in PBASIC 2 and Hello World appears on the display Now clear the screen in case there s text left from a previous run of the program Note that there s a 1 second PAUSE prior to sending any data to the Backpack of time to initialize the LCD after power up This gives the Backpack plenty Clear the LCD screen Print message ASCII followed by an address Move to line 2 and print Now we ll simulate a common application by printing a label on the screen and updating some data b2 li pause 2000 serout 0 n9600 I CLR pause 1 serout 0 n96 Again serout 0 n9600 I L1_C7 serout 0 n9600 DEC b2 b2 b2 1 pause 200 goto Again Scott Edwards Electronics Inc 00 Count by positioning
9. character generator CG RAM 64 addr X These instructions take more than 1 ms for the LCD to execute Pause at least 1 ms before sending additional data after these instructions At 2400 bps no pause is ever needed Advanced LCD users These are the actual LCD instruction codes When the Backpack receives the instruction prefix it clears the register select RS bit The next received byte is written to the LCD with RS low After writing that byte it returns RS high normal data mode This approach means that you can send any valid LCD instruction through the Backpack Since the Backpack intializes the LCD at startup you should not send any initialization instructions If you did not understand the preceding note don t worry You don t need to know any of this to use an LCD with the Backpack The info may be handy to advanced users adapting programs written to drive the Backpack to applications that drive the LCD directly through the parallel bus Positioning the Cursor You can position the cursor anywhere on the screen by sending the proper instruction The arrangement of character positions depends on the type of LCD as shown in figure 4 below one line LCDs other than 1x16 set LINES switch to 1 character aanp pap position set position 428 129 130 131 132 133 134 es instruction two line LCDs set LINES switch to 2 4 0 1 2 3 4 5 6 eee line 1 128 129 130 131 132 133 134 ee line 2 192 193 194 195 196 197 19
10. e Worst case tolerance for any dimension is 0 50mm Locate the terminals Maximum depth from front of screen frame to tips of marked Aand K nexttothe _4 sy 10 to 33Q interface header posts is 26mm LCD screen and connect I K Dimensions based on information provided by to power as shown gE aaz 0 8 manufacturers subject to change without notice R Figure 7 Physical dimensions and backlight connection Revision History Basic Specifications As of 03 98 the LCD Serial Backpack has been in continuous production for more than four years Table 2 summarizes the revisions Note that pcb update does not necessarily indicate a change in the board layout but a change in pcb manufacturing facility or generation of fresh tooling Table 2 Revisions wi eda gvatiga s dace Seysasnijslecyadeie E sieve suasies 2400 baud only 9600 baud capability added Saceueteretsecteshecet NE minor pcb updates ATTA firmware changed to use instruction prefix P E E A T minor pcb updates E E E T jumpers changed to configuration switches REV 6 wcescecctass cece minor pcb updates later rev 6 models display test msg E ATE EEAS when SER pin is connected to 5V throughout startup Table 3 Basic Power requirements incl typical LCD 4 8 to 5 5 Vdc 3 mA Specifications User CONNECtOp sinian oaae Five 0 025 pins on 0 10 centers Connector PiNOUt sisira iasosieseciec ienee 5 GND SER GND 5 Serial input
11. here s text left from a previous run of this program Note that of code The first opens at 9600 baud you need a delay after clearing the screen To create a i delay you can use a timing instruction such as First Power BASIC s the serial port for output DELAY or QBASIC s SLEEP or you can send an unnecessary instruction the second prints text to such as lt 254 gt lt 128 gt That sequence moves the cursor to the beginning of it Type and run these lines line 1 which is where it already is thanks to clear screen PRINT 1 CHR I CHRS CLR Send lt 254 gt lt 1 gt to clear screen in QBASIC on ROWS ls PRINT 1 CHRS I CHRS LINE1 Time delay for 9600 baud BASIC and Hello World i appears on the display Now print some text PRINT statements should end with to prevent unnecessary carriage return line feeds which the Backpack doesn t understand and displays as junk characters PRINT 1 Hello world Positioning the cursor requires sending the instruction prefix ASCII 254 which we ve assigned the name I followed by an address We ve assigned names to ASCII 128 lst character of line 1 and 192 lst character of line 2 We ll position the cursor to the start of line 2 and print some more PRINT 1 CHR I CHRS LINE2 press return Wait for a keypress at PC before continuing CLS INPUT PRESS RETURN TO CONTINUE X Now we ll simulate a common application by printing a
12. imple animations See the Backpack application notes at www seetron com for more examples Bitmap Layout Symbol Locations Example Loading the Symbol Byte Values ASCII Base To load the arrow shown at left to symbol 3 SESE en esate Code Address a program would send the following bytes to byte 0 xxx00000 0 0 64 the LCD byte 1 E xxx00100 4 1 72 lt 254 gt lt 88 gt Point to symbol 3 byte 2 o xxx00010 2 a0 Seog dneni byte 3 xxx11111 31 lt U gt lt 4 gt lt c gt lt 01 gt pend MED byte 4 z m 7 xxx00010 2 3 88 lt 2 gt lt 4 gt lt 0 gt lt 0 gt patom bytas il BER i 4 96 lt 254 gt lt 128 gt Move cursor back byte 6 xxx00000 0 5 104 to the screen byte 7 xxx00000 0 6 112 7 120 lt gt means a byte set to the value See the program examples Figure 5 Defining custom symbols 160 168 176 216 To find the ASCII code for a given character add the row and column numbers For example capital D is in the column marked 64 in row 4 so its ASCII code is 68 Use the reverse procedure to determine the symbol for a given code For example ASCII code 244 produces the symbol Q found at colum 240 row 4 i NOTE Custom characters occupy ASCII 0 7 Backpack loads patterns shown at startup ASCII 8 31 repeat the custom characters ASCII 128 160 are blanks Figure 6 LCD character set 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA
13. label on the screen then updating some data by positioning the cursor Each time you press return on the PC the program will add 1 to the count and update the value on the screen Notice that to position the cursor at character 6 of line 1 we give the position value of LINE1 6 This is easier to read than 134 which is the address of line 1 character 6 Also note that we print several spaces after the number It s not needed here but in programs in which a number could be _lower_ than the previously displayed value the spaces would erase any leftover digits PRINT 1 CHR I CHR CLR CHR I CHRS LINE1 PRINT 1 Count CHR I CHR LINE2 press return theCount 0 Again PRINT 1 CHR I CHR LINE1 6 theCount 3 INPUT ENTER TO CONTINUE Q ENTER TO QUIT X IF UCASES X Q THEN END theCount theCount 1 GOTO Again Scott Edwards Electronics Inc 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 7 Program BPKDEMS1 BAS This program demonstrates fundamental techniques of driving the LCD Serial Backpack R in BASIC from the BASIC Stamp I It assumes that the Backpack is connected to I O pin 0 of the Stamp and that it is set for 2400 bps Start by defining some useful constants for the Backpack SYMBOL I 254 Instruction prefix value SYMBOL CLR 1 L
14. over header k 4 stakes and stakes and Figure 2 Mounting the Backpack to an LCD Quick Checkout and Contrast Adjustment You can test the Backpack and LCD for proper operation without a computer serial port Temporarily connect the serial input to one of the 5 terminals of J 1 then connect power to 5 and GND Backpacks with pcb revs 5 and 6 made before March 1998 will display rows of triangles across the display Later rev 6 and higher units ones shipped with this manual will display a text message Units earlier than rev 5 will produce unpredictable results with this test so they should be tested with an actual serial input The contrast control is usually set fully clockwise at the factory This setting may be too dark with some LCDs Use a small flat blade screwdriver to adjust the contrast H 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 3 Configuration Display Lines Set the LINES switch figure 1 down for 1 line displays up for 2 or 4 line displays Note that most 1x16 displays behave like 2x8 displays with the two lines side by side If you havea 1x16 LCD and cannot see the second eight characters power down and switch to the 2 4 line setting Baud Rate Set the BPS switch down for 2400 baud up for 9600 At either rate the serial characteri
15. rs This manual in its entirety is copyright Scott Edwards Electronics Inc 1998 H 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 2 Description of the Backpack Board Installation to Typical LCDs Figure 1 shows the major features and configuration options of the Backpack circuit board Figure 2 shows how to mount it to typical LCD modules 5V Contrast h darker A aX GND ae gt Serial data gt LINES switch Duplicate 5V and GND down 1 line LCD up multiline LCD connections see text S555655 BPS switch down 2400 baud up 9600 baud Do not reverse 5V and GND even momentarily Reversed power will destroy the electronics Do not exceed 5 5V into 5V Overvoltage will damage the unit or shorten its life Figure 1 The LCD Serial Backpack circuit board LCD connector styles that 2x7 connector 1x14 connector work best with the Backpack Solder header stakes to LCD 2x7 pads Solder header stakes to LCD 1x14 pads component side view of LCD Peel and stick Peel and stick Backpack foamtapeas Backpack foam tape as component side up shown Slide component side up shown Slide solder solder pin 14 LCD module face down LCD module face down foam tape foam tape Backpack J3 Backpack J2 Ea over header
16. stics are no parity 8 data bits 1 stop bit NOTE The Backpack reads the configuration switches only at startup Change switch settings only with the power off Hookup for Use Figure 3 shows how to connect the LCD Serial Backpack to PCs and BASIC Stamp computers in order to run the example programs presented later in this manual Refer to figure 1 or the markings on the Backpack for the locations of 5 GND and SER ial in The 5 pin connector on the Backpack has two extra pins for 5 and GND These pins are arranged in a pallindrome layout If you make a matching 5 pin connector the connections will always line up properly regardless of connector orientation Suitable female crimp sockets for making connectors are available from J ameco www jameco com PN 100765 Digi Key carries ready made 5 pin socket and flex cable assemblies in varying lengths www digikey com PN A9BAG 0506F N D PC Serial comm Port BASIC Stamps Backpack Stamp Backpack m SER GND Vss __ GND DB 9 female solder side oi a ooo 5V Vdd _ 5 n lt 5 T 1 O pin 0 SER _ _ power supply Figure 3 Connecting to PC serial port BASIC Stamps Basic Operation Once the Backpack is properly connected and configured to match the baud rate of the computer program that will be talking to it serially data sent to the Backpack will appear on the display For example if you send Hello to
17. the Backpack Hello appears on the display The cursor printing position automatically advances from left to right You can also send instructions to the LCD via the Backpack To tell the Backpack that a particular byte is an instruction and not text precede it with the instruction prefix character ASCII 254 OF E hex 11111110 binary The Backpack treats the byte immediately after the prefix as an instruction then automatically returns to data mode An example The clear screen instruction is ASCII 1 To clear the screen send lt 254 gt lt 1 gt where the lt gt symbols mean single bytes set to these values not text as typed from the keyboard Table 1 lists the LCD instructions H 2700 E Fry Boulevard Suite A4 Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 Net www seetron com Users Manual BPK XXX v6 0 03 98 pg 4 Table 1 LCD Instructions Instruction Action Code X Clear Screen 1 Scroll display one character left all lines 24 Scroll display one character right all lines 28 X Home move cursor to top left character position 2 Move cursor one character left 16 Move cursor one character right 20 Turn on visible underline cursor 14 Turn on visible blinking block cursor 13 Make cursor invisible 12 Blank the display without clearing 8 Restore the display with cursor hidden 12 Set cursor position DDRAM address 128 addr Set pointer in
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