Question about using PIC OR ATMEL

[kobre98]

I want to make a Rotating led display in which I will connect 30 leds that will light at the same time,
I tried to this with PIC but it miss function cause of current drain !!!
Could this be done with ATMEL AT89C51 ?!?!

 

[nick703]

put some your circuit diagram or code.

 

[kobre98]

it's not ready yet, but it involve 30 led with 220 resistor for each connected to 30 pins of the micro-controller

 

[nick703]

it's not ready yet, but it involve 30 led with 220 resistor for each connected to 30 pins of the micro-controller

so 30 pin use then which micro controller u used ? and what is your resistor value? and your goal is light up all L.E.D right ?

 

[kobre98]

I used PIC18F and PIC16F
with resistor value 220 ohm
it didn't work
I heard that I can use AT89C51 and it can provide more power

 

[pasicr]

On pic mcu you have max 20mA per pin, dont forgot this info....

 

[kobre98]

I know but what a bout AVR ?!

 

[pasicr]

http://www.atmel.com/images/doc0265.pdf
read detailed page no.10 of this datasheet,
regards

 

[jayanth.devarayanadurga]

Do you want to turn ON/OFF each LED individually or or you multiplexing some or all of them? You can use 4 X 74HC595 to drive 32 LEDs and it connects to micro with 3 pins. You need micro with 3 digital IO pins and some 2KB ROM. You can also use any 14 pin IC with I2C/SPI and use 2 X MCP23017/23S17. If you can get any 8 pin micro with I2C/SPI then it is also ok or you can use 8 pin micro with software i2c/spi.

**broken link removed**

 

[kobre98]

thanks for your reply but I really need something compact, I don't need more ICs to be attached to the system, I just want a controller and the LEDs
since it will be rotating using a motor and I can't afford additional weight on the motor head

 

[nick703]

rotating using motor means input as a motor and led blink as a rotate motor state ?

 

[jayanth.devarayanadurga]

Ok. The whole micro board is rotated using motor like in POV. Right? 30 LEDs lie on the radius of the circular board?

Edit: This is the best micro for your project. Instead of using a 40 pin micro you can use 2 X 16- bit portexpanders and 8 pin micro with i2c. It won't take much space. You can even get SMD versions of port expanders.

https://www.hobbytronics.co.uk/microchip-12f1822

https://www.hobbytronics.co.uk/datasheets/12F1822.pdf

 

[wp100]

thanks for your reply but I really need something compact, I don't need more ICs to be attached to the system, I just want a controller and the LEDs
since it will be rotating using a motor and I can't afford additional weight on the motor head

Hi,

You still have not answered the key question, how many leds will be on at any one time ?

A typical Pic 16F or 18F micro can handle up to 25ma per output pin BUT the total load on the chip is about 200-300ma so that limits how many leds you can drive directly.
Thats a different current load if you are multiplexing the leds, which again you do not say.

 

[kobre98]

Hi,

You still have not answered the key question, how many leds will be on at any one time ?

A typical Pic 16F or 18F micro can handle up to 25ma per output pin BUT the total load on the chip is about 200-300ma so that limits how many leds you can drive directly.
Thats a different current load if you are multiplexing the leds, which again you do not say.

I want to light the 30 leds at the very same time, and does ATMEL support only 200-300ma as well ?!

 

[Venkadesh_M]

Hi check the sinking current limitation and connect the current limiting resistors as to divide the current to 30 individual LEDs....

 

[jayanth.devarayanadurga]

This is the best circuit for you. LEDs and resistors packs are needed for circuit using any micro. The space taken by 2 X port expanders and micro is less than that of 40 pin micro.

Another method is using one 74HC595, PIC12F1823, ULN2803 or 4 PNP transistors. Each transistor will drive 8 LEDs. 4 pins for transistors, 3 pins for 74HC595 (total 7 pins in micro). Multiplexed display. 8 leds turn ON at a time for a short period and then turn OFF.