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!

 

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.

 

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.

I will use a uC with a minimum 40 pins for I/O(32+8). I think any idea will help me.

 

Here's what I did for a 5x7 matrix:

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.

 

Here's what I did for a 5x7 matrix:
View attachment 153441
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.

Thank you!