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Topic: Shift registers? Display Drivers? Comparison (Read 959 times) previous topic - next topic

danielNC

Is there a good comparison chart of information that can explain the differences in shift registers or LED display drivers.  I have been using the Max7221, but I an curious to know differences or reasons for using other things that seem to pop up.

Ex.  max7219, max7221, 74HC164, TLC5940, 4021?   ????

Thank you in advance for your help.

CrossRoads

Sounds like a good challenge for you. Put a chart together comparing ease of use, # of LEDs, voltages that can be directly supported, ease of PWM capability, ease of use with LED matrix, RGB LED, single LEDs, multiplex support needed, etc.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

danielNC

Yeah, I was hoping someone had already done this.  I do not know enough yet.  Is there a explanation/comparison chart or article?

Cheers,
Dan

CrossRoads

Not that I know.
Start with the part you are familiar with, the MAX7221, and come up with a summary of what you know as a starting point:
64 LEDs, 5V, SPI interface, etc. Come up with a table format to put the characteristics into,  and go from there.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

dhenry

You can probably compile a more comprehensive list, however, my take:

1) max7221 / 7219 are practically the same.
2) minor differences between hc164 and hc595.

leds to drive: max7221 / 7219 / 5940 can drive a lot of leds. in the case of those first two, up to 64 leds. hc164/595 can drive up to 8 leds.
types of leds to drive: max7221/7219 only common cathode. hc164/595 can drive any leds.
driving mechanism: max7221/7219/5940 are constant current type drives. hc164/595 requires an external part to achieve that.
brightness control: 5940 can control individual led's brightness. 7221/7219 can control only the brightness of all leds. hc595 offers pwm capabilities but the user has to drive it. hc164 has no pwm capabilities.
working voltage: max7221/7219 cannot work reliably at 3.3v or lower (I think the datasheet suggests 4.xv minimum) - you may not be able to reliably initialize it. 5940 works down to 3.3v, as does hc164/595. 4021 works to 15v (per datasheet) or 18v (my experience).
signaling: 7221 follows spi convention (with a cs pin). Others don't.
latching: hc164 is transparent: the output sees the transmission. others offer output latching.
speed: I have driven hc164/595 to 32Mbps without any problem. I doubt others can.

That's what I can think of now. Others may add more.

CrossRoads

7219 & HC595 work just fine with SPI as well.
Common cathode vs common anode - there is no difference, they can be used interchangebly with a little thought.
Look at the attached - one is advertised as common cathode, one as common anode - where is the difference?
5940 is common anode only for sure as it only sinks current.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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