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5v propeller plans? — Parallax Forums

5v propeller plans?

effinrobotseffinrobots Posts: 1
edited 2011-01-31 22:42 in Propeller 1
Hi all,

I was wondering if anyone with some insight into the situation could chime in on this:
Are there any plans to produce propeller chips that operate on 5v instead of 3.3? It seems to me like a lot of readily available sensors and addons out there require 5v to run, and having the prop compatible with that out of the box would seemingly make the platform much more accessible for those who wish to get set up and going with little to no extra parts.

Is there some limitation I'm not aware of that prevents this? Am i just wishful thinking?

Enlighten me, please!

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2011-01-31 16:09
    There are no plans for a 5V Propeller. It would require a complete redesign of the chip and there's not enough of a market to pay for that. It would make the Propeller chip much larger and more expensive as well. It's very easy to interface the Propeller with 5V chips. Most of the time you can connect an output pin directly to a 5V logic input and that will work fine. You can usually connect an input pin to a 5V logic output through a 2.2K resistor and that will work fine. There are many 3.3V to 5V logic converter chips that work well also. One of the "sticky" threads (Key Thread Index ... Technical Considerations) at the top of the Propeller forum thread list has a link to a discussion on interfacing the Propeller to 5V logic ... full of suggestions and examples.
  • LeonLeon Posts: 7,620
    edited 2011-01-31 16:11
    The semiconductor process used doesn't allow 5V operation. Most modern devices use a 3.3V supply, or an even lower voltage such as 1.2V, because of the narrow features required for operation at the required speed, as well as the density required,
  • Nick McClickNick McClick Posts: 1,003
    edited 2011-01-31 16:13
    Very unlikely. Interfacing with 5V devices isn't much of a problem though, just use an inline resistor (4.7k works great). Nearly all the Propeller development boards provide a 5V & 3.3V power rail, too.
  • RavenkallenRavenkallen Posts: 1,057
    edited 2011-01-31 16:13
    A lot of sensors may be powered by 5 volts, but the signal inputs can usually be triggered by 3.3 volts. A problem can arise when the sensor outputs a signal at 5 volts. This can be fixed by adding a voltage dropping resistor(Or in some cases a diode or two). Most Propeller boards have two regulators, a 3.3 volt and a 5 volt one, so you can power other peripherals. It seems like there are quite a few sensor/lcds/ other chips that run off of lower voltages. I think it is kind of annoying when i am playing with a 5 volt micro and have to lower the voltage to work with a 3 volt sensor. Your best bet is to find a work-around...
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-01-31 22:42
    It seems to me that a lot of us just expect to be able to plug in all and everything at a matching voltage and expect it to work. That approach is rather naive and really needs to be overcome to be at all adept at electronics.

    For similar reasons, many of us just use Ohm's Law, but ignore properly estimating the power ratings involved with a device. The results are usually something going up in some.

    If one is at all serious about learning electronics, adapting devices between 3.3volts and 5volts is a reasonable start. At this point, I have pretty much decided to use 12volt motors as there really aren't any good ones that are much smaller. So that is another voltage level.

    Why does the Propeller have to be 3.3V? As I understand it, the faster the chip is clocked, the more heat it creates. And the higher the voltage, the more heat that is created. Together, these physical limits made the Propeller designers arrive at 3.3volts in order to get the kind of speed that is required for video signal generation.

    There are some level shifter designs that are bi-directional. One of these could be used to make a board with a Propeller that was all 5Volt i/o. But I suspect as soon as you made all the i/o 5 volts, someone would want a few pins to be 3.3v because of some other chip or device.

    Be the engineer and just configure it as required rather than hope for a Lego's style universe. You will take your game to a higher level and appreciate electronics more. And you will begin to see how limitis and limitations are an important part of design, including the limitations of power and heat.
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