I2CChip.com: 4 Digit LED and LCD displays

Nothing matches the readability, size, brightness or low power of simple numeric displays.

6 different sizes 0.3" to 4.0"

Out of the Box

Realterm drives 3 LED displays directly. On the I2C tab, enter a string, and press display. Realterm does the seven segment decoding for you.

You can display various special characters and many letters as well as numbers. Just try them.

If you want to drive them with your own software you can use the I2CHelper DLL to make the hex string you need.

PutString('Y W0000000000'); //send 0's to reset 1st time after power on

S=Str2M5451D4('-1.23'); //turn text into 7seg data (routine in 'I2CHelper.M5451')

PutString('Y101'+S); //and send it to the display  (routine in 'Realterm.RealtermIntf')

Clearing the bus: After power on, the M5451 should be synchronised by sending 5 bytes of 0's to it. If you don't care about speed, just precede every send with five 0's, then you will never have a problem.

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Sizes:

(new displays may be added)

LED: 0.36" , 0.56", 1.0", 2.3", 4.0" high digits; 35 segments; dc brightness control

LCD: 0.5", 1.0"; 33 segments (uses std 40 pin dip, static LCD, 32mm pin spacing)

LED's from 0.56" and up are end stackable

Overlay Drawing of All modules (pdf)

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Interface Requirements:

These displays use the M545X family of IC's. The LED driver is M5451, LCD is M5452, and vacuum flourescent driver is M5453. All 3 use exactly the same control signals. They use CLOCK and DATA lines only. No chip select pin is needed.

The BL233 IC can drive these directly, one per bus. Note that these are not I2C displays, and so only one can be connected to each (of 3) buses of the BL233.

For more information see STM, National Semi, or Micrel, MM5451/2/3 data sheets.

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Power Requirements

The modules run off 5 V. The LED displays draw approximately 15mA per segment. LED brightness is adjusted by changing the value of the brightness resistor.

LED modules above .8" require an unregulated VCC > 5V for the LED's as these displays have multiple LED chips in series for each segment. The M5451 will stand 12V, but you have to watch the power dissipation of the IC is not exceeded with 35 outputs driven.

I2C Displays

If you need multiple displays from one bus, or want to use them easily from an embedded system our BL301 drives 4 numeric displays, and one character LCD module, as well as I/O pins to read switches or control led's as well.

We also have available an LED display based on the tda1064, for the I2C bus.

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I2CHelper DLL

The driver routine is in a in-process com server dll. You can call this through COM mechanisms from most languages or directly as a dll.

It turns ascii strings into a hex string to send to the BL233 driving the display. You can use Realterm to send strings to the display

Download DLL Before using you need to register it with run -> regsvr32 i2chelper.dll

The interface name is "I2CHelper.M5451"

% matlab example

hI=actxserver('I2Chelper.M5451'); % start helper

hRealterm=actxserver('Realterm.RealtermIntf'); %start serial interface

invoke(hRealterm,'PutString','Y W0000000000'); %send 0's to reset display after power on

S=invoke(hI,'Str2M5451D4','-1.23'); %turn text (-1.23) into 7seg data 

S=['Y101',S]; %put start bit infront of data

invoke(hRealterm,'PutString',S); %and send it to the display 

Linux Users: Ask for the pascal source. the free Kylix can be used to compile it as a linux .so.

Gory Details

When you use the I2CHelper DLL, you don't need to go into the details below. It has all the 7 segment lookup tables and bit mapping done for you.

The 35 bits of the M5451 are connected to the segments of the LED digits. Digit 1 is the LSD or rightmost digit. The M5451D4 modules use an optimum pcb layout. It is easiest to generate your 7 segment data in the NSM4000 arrangement, the move the bits per the "mapping" column. So move bit1 to bit31, and so on. Note that 3 segments of digit 5 can be operated on those modules which can have it fitted. This means you can have a 4.5 digit display.

Pinout

Connector Pin Usage. Only the larger boards need a 6 pin connector with the 12V, as they have several series diodes. Smaller boards only need the first 4 pins. Note these pinouts predate the current I2C bus connector.

+12 on multichip leds only, these are 1" and up.

Contact Information

sales@i2cchip.com
http://www.i2cchip.com
Phone +64 21 623-402

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