1.  Copyright   :  You can use  this App.-Note for free , if you use it for none profit applications .

                            The Program Driving a Single Digit LED-Dot-Matrix Display.bas  is part of this App.-Note.                           

2.  Disclaimer :  The author is not liable for any damages in connection with this App-Note.

3.  Electric savety :     The electronic of this application is supplied with 5VDC .

                                     Make sure that you use CE certified  power supply  to avoid  an  electric shock accident.

4. Motivation :  

     LED dot matrix display like the TA03-11 or LTP-305 or  TIL305  or MAN2 or ALS340A1....   ,

     are still popular , because of the vintage charm.

    This mentioned displays are pin compatible.

    To use this style of display it is necessary  to use a  multiplex driving system in best case with build-in

    ASCII Character Font.

    But it is not easy to purchase for private purpose integrated circuit with built-in

    ASCII Character Font and Multiplexing the LED Matrix.

    Also such circuits are expensive for amateurs.

    On the other hand you can find modules with such display with a multiplex driver circuit , but this circuit

    includes not a built-in  ASCII Character Font .  So you  need a library , so far I did not found a BASCOM-Lib.

    So this situation was the reason to think about how to use the dot matrix display like TA03-11SRT

    and pin compatible type.

    The hard work was to build the pattern data for the characters of the Character Font.

    Characters are follow the data in accordance to ASCII chart.

    The result is to spend for each display an own ATmega328P to build a addressable single digit module

    with a serial input RxD.

    16 modules can be addressed by 4 address-pins.

5. Technical Information :

    The module includes one ATmega328P and a LED-Dot Matrix Display and 7 resistors 360 Ohm for R1..R7 .

    The external module wiring is : GND ; +5V ; 4 termination for address ; RxD . Keep Reset / MOSI / MISO /

    SCK for  programming separate for each module.

    16 modules are selectable by address .

    All modules can be paralleled at the RxD input / GND / +5V .

    The module receive a command : address and information for decimal point dp and character.

    Please see the datasheet for ATmega328P and LED Dot Matrix Display.

    Please see the ASCII-Chart -> MSC BASCOM AVR Help Titel ASC.

    Program compares the command address and if the address fit to the hardware address , it show's the new   

    character  on the display.

    The command start with @ , it means "at" "address" "dp-on/off" "character" "CR" .

    Decimal point is an extra column C1 and is handled separate .

    The 5x7 Matrix is C2..C6 x R1..R7

    The Display is multiplexed at C2..C6 = Anodes times R1...R7 = Cathodes , incl. C1=Dp.

    For R1..R7 is used  PORTB , the information is ; byte for C2 .... ->  byte for C6

    5 times is PORTB multiplexed regarding C2...C6 ( PB0..PB6 is used for R1..R7 ; PB7 is not used ) .

    Columntime is the on-time for pixel , it can be changed if necessary .

    Delaytime is used for better contrast , it can be changed if necessary .

    The data are including the dot matrix pattern for each character .

    Label_0 decodes the command of received data at RxD.

    Label_1 build byte data for characters by using restore.

    Data are inverted for R1..R7 because of R1..R7 = cathodes see at the end of  Label_1 .

    So you  could also use  a display  with  C - line as Anode  , if you invert the information on

    PORTD.2..PORTD. 7  and  you  do not invert   R1..R7  see at the end of  Label_1.

    Also you can use other 5x7  LED-Dot Matrix  Display  without  decimal point  Dp ( C1 ) .

    Please see the program  Driving a Single Digit LED-Dot-Matrix Display.bas  .

    [ used BASCOM AVR 2.0.7.7 / purchased version ] .

    A possible arrangement of the module could look like Figure 1 . Please note , that the narrow board for the display is strictly not recommended for wave soldering the display.

    That's why please use a Precision IC-Socket 2,54 mm for the display.

    The narrow module allow a pitch of 10.16mm , if you  stagger  modules. 

Figure 1 :  Module  [ FreeCAD  0.20.1  ] ,  but follow your own ideas  .

    Figure 2 :  Module  schematic . [EAGLE Version 6.4.0 für Windows Light Edition]

The complete AN can be downloaded as PDF :  App-Note Driving a Single Digit LED Dot Matrix Display.pdf

The source code, HEX file and XLS file can be downloaded as well : AN#209.zip