LED matrix with sht 21 sensor and microcontroller MSP430 from Texas Instruments

Discussion in 'The Projects Forum' started by Mihaela Nastase, May 31, 2018.

  1. Mihaela Nastase

    Thread Starter New Member

    May 31, 2018
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    Hello all,

    I want to build a led matrix, size 32 columns x 8 lines

    I will built this from zero using 2835 LED(256 LEDS)
    I want to display dates from the sensor SHT21(temperature and humidity sensor) with a MSP430 microcontroller from Texas Instruments.
    For multiplexing I was thinking to use MOS-FET transistors.
    If anyone has an idea of schematics or circuits for this matrix please help.

    Thank you!
     
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Welcome to AAC!

    How many I/O's does the microcontroller have?

    With 10 I/O's, you can drive the rows and use two more to control shift registers; one for shift and one for reset.

    Don't have a schematic handy. I did this to implement a scrolling display on a 5x8 matrix.
     
  3. Mihaela Nastase

    Thread Starter New Member

    May 31, 2018
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    I will use a uC with a minimum 40 pins for I/O(32+8). I think any idea will help me.
     
  4. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Here's what I did for a 5x7 matrix:
    upload_2018-5-31_9-30-49.png
    You can replace the transistors with logic level MOSFETs. Adding another row and more columns is straightforward.

    In my code, I populated a 2D array with the information I wanted to display and wrote it out a column at a time.

    You need to refresh the columns at at least 100Hz to avoid flicker. Since the LEDs are multiplexed, you should drive them at a higher current than what is allowed at DC for sufficient brightness. You also need to address LED power dissipation if multiplexing stops and a column is displayed continuously.
     
    Mihaela Nastase likes this.
  5. Mihaela Nastase

    Thread Starter New Member

    May 31, 2018
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    Thank you!
     
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