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I have opened the PCB of an old device in order to use its LCD screen, the problem is that the pcb indicates no model ID or whatsoever. I was wondering if someone could give me a hint here of whether it is possible to control what the screen displays. What I do know about the LCD screen is that it has 28 pins, And I googled the LCD controller model number, it gave me a datasheet of "16-Bit Ultra-Low-Power Microcontroller, 8kB Flash, 256B RAM, Comparator, 96 segment LCD", but that does not help me with the pinout of the screen if I want to connect it to the arduino.

m430f413

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I'd be grateful if anyone could help me with this, thanks :)

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  • \$\begingroup\$ The image is tiny. An it would be helpful to know what device the part was ripped from. \$\endgroup\$
    – Eugene Sh.
    Aug 11, 2015 at 15:24
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    \$\begingroup\$ If that uC you mention is a mcp430f413 it will contain some software that defines the function of the PCB, including cotrolling the LCD: it is not an LCD PCB that is meant to be controlled by some external device like an Arduino. \$\endgroup\$
    – Wouter van Ooijen
    Aug 11, 2015 at 15:26
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    \$\begingroup\$ From what i see, you can easily track the lines going to LCD from the MCU, and as the MCU has a built-in LCD controller, I believe you could cross-reference the pin numbers with their functions. P.S. I don't believe you will be able to control it with Arduino... \$\endgroup\$
    – Eugene Sh.
    Aug 11, 2015 at 15:28
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    \$\begingroup\$ That LCD is likely something like a custom triplexed (or more) LCD glass only. You would have to have a controller suited for the actual display. If you can see the number of segments you can make pretty good guess as to the multiplex ratio (# of pins = N/ratio + ratio, so a 28 pin LCD glass that is triplexed could have 75 segments (including annuciators and decimal points). \$\endgroup\$
    – Spehro Pefhany
    Aug 11, 2015 at 15:31
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    \$\begingroup\$ This is a generic (well, custom) multi segment lcd. You would have to individually drive each segment. You are much better off getting a character lcd (hd44780 compatible) or some graphic lcd like the hobbyist nokia lcds. \$\endgroup\$
    – Passerby
    Aug 11, 2015 at 15:59

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As the comments have suggested, it is unlikely that you can control the LCD glass directly with your Arduino. That said: you CAN put this to a new use if you put the effort required into the project.

You have already started. You need to identify the microcontroller and follow the traces from the LCD display back to the micro. Then use the datasheet to work out how the controller is talking to the display.

Then you need to identify the LCD segments. This will most likely require that you write custom code for the micro to run through all of the multiplex possibilities and note which segment lights up as you go through each one.

Finally, write new custom code that makes the microcontroller drive the display the way you want. For example, you could implement a serial protocol that listens for commands from your Arduino and displays the result of those commands on the display.

This is actually a fabulous learning exercise should you decide to do it. You will learn much from the process.

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  • \$\begingroup\$ The MCU in the photo has an integrated 96 segment lcd driver peripheral multiplexed with the GPIO peripheral on 24 pins. Arduino may be able to do so possibly with a port expander, a RPI or other denser kit with more gpio pins will work. \$\endgroup\$
    – crasic
    Aug 11, 2015 at 16:53
  • \$\begingroup\$ I'm not sure I agree that this is a good learning exercise. It requires a JTAG connection to the MSP430, which means buying a JTAG emulator and soldering wires to the board. Then they'll have to learn how to write MSP430 code, unless there happens to be a TI example that works correctly. The LCD module in the user's guide doesn't look all that complicated, but it's probably too much for a beginner. I second Passerby's recommendation: pick up an HD44780-compatible LCD module; it'll be much, much easier to work with. \$\endgroup\$
    – Adam Haun
    Aug 11, 2015 at 16:55

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