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Energy meter glass lcd module

Dharani Rajagopal
Prodigy 50 points

Other Parts Discussed in Thread: MSP430G2553

Dear All,

                 I am doing energy meter project. And the energy consumption is displayed using LCD module (8 digit ) with driver IC. And i am planning to remove LCD driver IC and try to control the LCD by the controller (MSP430G2553). Please tell me weather it is possible or not. If it is possible please help me to proceed. Thank you.

  • 0
    Guru 227245 points

    Only the MSP430F4xx and F6xx devices have an internal glass LCD controller. The 2x (specially the low-cost G series) devices won't provide the required analog signals for driving LCD segments directly.

  • 0 in reply to Jens-Michael Gross
    Prodigy 50 points

    Thanks for your suggestion. But in TI website MSP430G2553 application note they have given as MSP430G2553 can be used as glass lcd driver as well and with some example code. please suggest me weather that code will work or not. Thank you.

  • 0 in reply to Dharani Rajagopal
    Guru 227245 points

    I looked into this (fairly new) appnote, and indeed, it talks about simulating the LCD driver hardware by software.

    Basically, you have to switch port pins so that the LCD glass sees a 30-300Hz AC signal where off segments have same and on segments have opposite signal polarity.

    The softwware is really straight. Almost like driving a multiplexed LED digit.

    However, the probelm is that the signal has to be AC, so the softwar eneeds to be really fast or you'll see ugly shadows (segments that appear partially on or off when they shouldn't) because you simply cannot change all the port pins at the same time. A fast running CPU and a really optimized algorithm wouold be of help.

    Th eother problem is that the 'real' LCD driver works with multi-level voltages for multiplexed glass LCD. The software solution can only produce +-VCC signals, so multiplexing is quite difficult if possible at all. And even on a non-multiplexed display, you have no control over contrast and you may even overload the LCD, decreasing the lifetime.

    On the bottom line, it is a nice idea and will work, but won't be a good thing because of

    - no multiplexing
    - no contrast (voltage level) control
    - high CPU load
    - tight timing requirements for a good display
    - requirement of many signal lines while the G series MSPs only have so few port pins.
    - probably reduced LCD lifetime

    So I'd say it' s a toy job, but nothing for a real application. But it would work.

  • 0 in reply to Jens-Michael Gross
    Prodigy 50 points

    Ya you are correct. thank you.

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