Table of contents:

Pinouts

Talking to the Module

Creating a Character

Character Map

Displaying a Character

Circuit Diagram

Basic Sample Software

Scrolling Text

character - Hex - ascii converter

Javelin Stamp Software

java class for driving the display

Talking to the Module

To display a character, you need to send a byte to the module, then strobe the digit you want that character displayed on.

Creating a Character

To display a character on any digit, a 8 bit code is sent to that digit. One bit for each segment.

The format of the byte is as follows:

For example, to display "8." send 11111111 to the display (255 decimal, FF hexadecimal).

To display "8" send 01111111 to the display (127 decimal, 7F hexadecimal).

The byte is sent to the module MSB first.

Displaying a Character.

Once you have sent the byte to the module, you will need to strobe the digit/s you wish the character to be displayed on.

For example, to display a character on digit 0, pulse pin 5 high then low. To display the same character on digits 0 and 1, pulse both pins 5 and 7 high then low.

Circuit Diagram.

Software Samples.

The following samples are written in PBasic for the Parallax BS2.

Scrolling text:

A simple demonstration to show that almost anything is possible with the LENNARD Display Module, including a fancy effect as animated displaying of characters.

'{$STAMP BS2} 'April 2002. Ben Lennard. 'Quick demo which scrolls "LENNARD" across my 5 'digit display 'The display would be like this: '____L '___LE '__LEN '_LENN 'LENNA 'ENNAR 'NNARD 'NARD_ 'ARD__ 'RD___ 'D____ '_____ 'Thats 12 steps in total 'Therfore, we will need a For loop for starters, that counts from 1 to 12 'and another For loop within that loop, along with conditional statements 'to determine what we need to display on each digit... '*****DECLARE VARIABLES***** 'DATA for the Display's Character Lookup Table, EEPROM address 0 to 7 data 56,121,55,55,119,49,94,0 'LENNARD 'CONSTANTS clock CON 6 'P6 = clock to 4094's pin 3 datapack CON 5 'P5 = Data to 4094's pin 2 'VARIABLES strobedigit var nib 'a four bit variable used to determine which digit to update character var byte 'the data to send to the display a var nib 'a for loop variable b var nib 'a for loop variable startletter var nib 'determines which character to start with endletter var nib 'determines which character to finish with spaces var nib 'used to make sure the correct digit is strobed '*****MAIN PROGRAM***** start: Gosub blankdisplay startletter = 0 endletter = 0 spaces=0 for b = 1 to 12 for a = startletter to endletter read a, character strobedigit = spaces + endletter - a gosub loadregisters next 'determine the speed of scrolling by the pause statement pause 200 endletter = endletter + 1 'as we only have 5 digits, we need to check if we 'need to change the start letter... if endletter > 4 then incrementstartletter goto endofroutine incrementstartletter: if endletter > 7 then endlettermax startletter=startletter + 1 goto endofroutine endlettermax: endletter = 7 spaces = spaces + 1 startletter=startletter + 1 endofroutine: next goto start blankdisplay: SHIFTOUT datapack, clock, msbfirst, [0] 'blank display for a = 0 to 4 pulsout a,1 'Strobe each digit next return loadregisters: SHIFTOUT datapack, clock, msbfirst, [character] 'Send data to the display PULSOUT strobedigit,1 'Strobe required digit to display the data return

CHARACTER - HEX ASCII converter

Use a terminal emulator such as Hyperterminal or Clarisworks data transfer to communicate with the Stamp Microcontroller. Set to 2400, 8, N, 1.

'{$STAMP BS2} 'March 2002. Ben Lennard. 'Program to demonstrate how to interface to the LENNARD5 Digit 'LED display module. Plus, how to communicate with a PC, and display the 'Hexadecimal ASCII code of any keys pressed on the keyboard. 'The outputs from the 4094 registers correspond to the Digit segments as follows: 'MSB -> .GFEDCBA <-LSB 'To write to a digit, do the following: '1. Send data. '2. Strobe the digit/s you want to display the data 'What this program does: 'Receives data from the PC everytime a key is pressed, and displays the 'Decimal and Hexadecimal value of that Key's ASCII code. 'Data received from the PC will be 8 bits, so we need to translate that 8 bits 'in to two sets of nibbles. Then, we use those nibbles to look up the actual byte 'we need to send to the 4094's to display the correct data. 'Example: If we send "Z" via the serial port, we will receive the following byte: 01011010 'Which is "5A" in Hexaedecimal. 'To display that value on the "LENNARD Display module": Split the byte in to two nibbles. 'The lower nibble, 1010 (Hexadecimal = "A", Decimal "10") 'will make the program look up position 10 in the table, and then sends that data 'in the table to the display, digit A. 'The upper nibble, 0101 (Hexadecimal and Decimal = "5") will make the program look up 'position 5 in the table, and then sends that data in the table to the display, digit B. '*****DECLARE VARIABLES***** 'DATA for the Display Character Lookup Table (EEPROM address 0 to 20) data 63,6,91,79,102,109,125,7,127,111 '0-9 data %01110111,%01111100,%00111001,%01011110,%01111001,%01110001 'A-F data 63,%00111000,%00111000,%01111001,%01110110 'O,L,L,E,H ("HELLO") 'CONSTANTS clock CON 6 'P6 = clock to 4094's pin 3 datapack CON 5 'P5 = Data to 4094's pin 2 'VARIABLES strobedigit var nib 'a four bit variable used to determine which digit to update '5 digits, 0 to 4 character var byte 'the data to send to the display datafromPC var byte 'the data from the PC a var byte 'just a FOR loop variable nibble var nib 'used to store the lower or upper 4 bits of "datafromPC" divider var byte '*****MAIN PROGRAM***** 'Set up the display Gosub blankdisplay 'display "HELLO" for a = 16 to 20 'go to EEPROM address "a" and store the data at that address in "Character" read a, character 'Send "character" to the display module, and display on the digit 'determined by "strobedigit" strobedigit=a-16 gosub loadregisters next pause 3000 'blank display again Gosub blankdisplay   ReadSerialPort: SERIN 16, 396, [datafromPC] 'Using builtin serial port, 2400baud, 8, N, 1 if not datafromPC = 27 then keepgoing 'If ESC pressed, send a message back to the PC SEROUT 16, 396, [" Microcontroller demo. Ben Lennard 3/2002"] keepgoing: if datafromPC = 27 then ReadSerialPort GOSUB DisplayASCIIcode GOTO ReadSerialPort DisplayASCIIcode: nibble = datafromPC 'transfer lower 4 bits of byte to nibble 'NOTE: As "nibble" is a nibble, and "datafromPC" is a byte, 'then only the lower half of "datafromPC" will be passed to "nibble" read nibble, character 'lookup data in table to send to the display 'load that data in to Digit A strobedigit=0 gosub loadregisters nibble = datafromPC >> 4 'transfer upper 4 bits of byte to nibble read nibble, character 'lookup data in table to send to the display 'load that data in to Digit B strobedigit = 1 gosub loadregisters DisplayDECIMALcode: '(this code added 25/3/2002) 'This is a little more difficult than working out 'the HEX code (simply spliting the byte in to two nibbles) 'as we can have up to 3 digits. So, we need to split the 'decimal version of the character in to 3 parts to display... 'The following code takes advantage of the fact that the Stamp 'and similar Microcontrollers only do Integer maths without 'an external floating point coprocessor attached. 'Figure out hundreds unit (doing 100's then 10's then 1's, rather 'than 1's, 10's, 100's saves 6 bytes of EEPROM! As this way you don't need to repeat code) nibble = datafromPC / 100 'eg: 214 / 100 = 2.14 (integer maths drops the .14) strobedigit = 4 read nibble, character gosub loadregisters 'eg: load 01011011 in to digit 4, which displays a 2. 'Figure out tens unit divider = nibble * 100 'eg: 2 * 100 = 200 divider = datafromPC - divider 'eg: 214 - 200 = 14 nibble = divider / 10 'eg: 14 / 10 = 1.4 (integer maths drops the .4), so nibble = 1 strobedigit = 3 read nibble, character gosub loadregisters 'eg: load 00000110 in to digit 3, which displays a 1. 'Figure out ones unit divider = datafromPC / 10 'eg: 214 / 10 = 21.4 (integer maths drops the .4) divider = divider * 10 'eg: 21 * 10 = 210 nibble = datafromPC - divider 'eg: 214 - 210 = 4 strobedigit = 2 read nibble, character 'eg: read EEPROM address 4 (which has 01100110 stored in it) 'store value in EEPROM address 4 in character '(turn on decimal point to seperate Dec from Hex on the display, eg: 188.BC) character = character + %10000000 gosub loadregisters 'eg: load 01100110 in to digit 2, which displays a 4. return blankdisplay: SHIFTOUT datapack, clock, msbfirst, [0] 'blank display for a = 0 to 4 pulsout a,1 'Strobe each digit next return loadregisters: SHIFTOUT datapack, clock, msbfirst, [character] 'Send data to the display PULSOUT strobedigit,1 'Strobe required digit to display the data return